EssentialsofEcology

SUPPLEMENT

1 Measurement Units, Precision,
and Accuracy (Chapter 2)

LENGTH Metric–English
1 liter (L) ϭ 0.265 gallon (gal)
Metric 1 liter (L) ϭ 1.06 quarts (qt)
1 kilometer (km) ϭ 1,000 meters (m) 1 liter (L) ϭ 0.0353 cubic foot (ft3)
1 meter (m) ϭ 100 centimeters (cm) 1 cubic meter (m3) ϭ 35.3 cubic feet (ft3)
1 meter (m) ϭ 1,000 millimeters (mm) 1 cubic meter (m3) ϭ 1.30 cubic yards (yd3)
1 centimeter (cm) ϭ 0.01 meter (m) 1 cubic kilometer (km3) ϭ 0.24 cubic mile (mi3)
1 millimeter (mm) ϭ 0.001 meter (m) 1 barrel (bbl) ϭ 159 liters (L)
1 barrel (bbl) ϭ 42 U.S. gallons (gal)
English
1 foot (ft) ϭ 12 inches (in) MASS
1 yard (yd) ϭ 3 feet (ft)
1 mile (mi) ϭ 5,280 feet (ft) Metric
1 nautical mile ϭ 1.15 miles 1 kilogram (kg) ϭ 1,000 grams (g)
1 gram (g) ϭ 1,000 milligrams (␮g)
Metric–English 1 gram (g) ϭ 1,000,000 micrograms ((g)
1 kilometer (km) ϭ 0.621 mile (mi) 1 milligram (mg) ϭ 0.001 gram (g)
1 meter (m) ϭ 39.4 inches (in) 1 microgram (␮g) ϭ 0.000001 gram (g)
1 inch (in) ϭ 2.54 centimeters (cm) 1 metric ton (mt) ϭ 1,000 kilograms (kg)
1 foot (ft) ϭ 0.305 meter (m)
1 yard (yd) ϭ 0.914 meter (m) English
1 nautical mile ϭ 1.85 kilometers (km) 1 ton (t) ϭ 2,000 pounds (lb)
1 pound (lb) ϭ 16 ounces (oz)
AREA
Metric–English
Metric 1 metric ton (mt) ϭ 2,200 pounds (lb) ϭ 1.1 tons (t)
1 square kilometer (km2) ϭ 1,000,000 square meters (m2) 1 kilogram (kg) ϭ 2.20 pounds (lb)
1 square meter (m2) ϭ 1,000,000 square millimeters (mm2) 1 pound (lb) ϭ 454 grams (g)
1 hectare (ha) ϭ 10,000 square meters (m2) 1 gram (g) ϭ 0.035 ounce (oz)
1 hectare (ha) ϭ 0.01 square kilometer (km2)
ENERGY AND POWER
English
1 square foot (ft2) ϭ 144 square inches (in2) Metric
1 square yard (yd2) ϭ 9 square feet (ft2) 1 kilojoule (kJ) ϭ 1,000 joules (J)
1 square mile (mi2) ϭ 27,880,000 square feet (ft2) 1 kilocalorie (kcal) ϭ 1,000 calories (cal)
1 acre (ac) ϭ 43,560 square feet (ft2) 1 calorie (cal) ϭ 4.184 joules (J)

Metric–English Metric–English
1 hectare (ha) ϭ 2.471 acres (ac) 1 kilojoule (kJ) ϭ 0.949 British thermal unit (Btu)
1 square kilometer (km2) ϭ 0.386 square mile (mi2) 1 kilojoule (kJ) ϭ 0.000278 kilowatt-hour (kW-h)
1 square meter (m2) ϭ 1.196 square yards (yd2) 1 kilocalorie (kcal) ϭ 3.97 British thermal units (Btu)
1 square meter (m2) ϭ 10.76 square feet (ft2) 1 kilocalorie (kcal) ϭ 0.00116 kilowatt-hour (kW-h)
1 square centimeter (cm2) ϭ 0.155 square inch (in2) 1 kilowatt-hour (kW-h) ϭ 860 kilocalories (kcal)
1 kilowatt-hour (kW-h) ϭ 3,400 British thermal units (Btu)
VOLUME 1 quad (Q) ϭ 1,050,000,000,000,000 kilojoules (kJ)
1 quad (Q) ϭ 293,000,000,000 kilowatt-hours (kW-h)
Metric
1 cubic kilometer (km3) ϭ 1,000,000,000 cubic meters (m3) Temperature Conversions
1 cubic meter (m3) ϭ 1,000,000 cubic centimeters (cm3) Fahrenheit (°F) to Celsius °C):
1 liter (L) ϭ 1,000 milliliters (mL) ϭ 1,000 cubic centimeters (cm3)
1 milliliter (mL) ϭ 0.001 liter (L) °C (°F Ϫ 32.0) Ϭ 1.80
1 milliliter (mL) ϭ 1 cubic centimeter (cm3) Celsius (°C) to Fahrenheit (°F):

English °F ϭ (°C ϫ 1.80) ϩ 32.0
1 gallon (gal) ϭ 4 quarts (qt)
1 quart (qt) ϭ 2 pints (pt)

S2 SUPPLEMENT 1

Uncertainty, Accuracy, Good accuracy Poor accuracy Poor accuracy
and Precision in Scientific and good precision and poor precision and good precision
Measurements
Figure 1 The distinction between accuracy and precision. In scientific measurements, a measuring de-
How do we know whether a scientific measure- vice that has not been calibrated to determine its accuracy may give precise or reproducible results that
ment is correct? All scientific observations and are not accurate.
measurements have some degree of uncertainty
because people and measuring devices are not A dartboard analogy (Figure 1) shows the darts are to each other. Note that good precision
perfect. difference between precision and accuracy. Ac- is necessary for accuracy but does not guarantee
curacy depends on how close the darts are to the it. Three closely spaced darts may be far from
However, scientists take great pains to reduce bull’s-eye. Precision depends on how close the the bull’s-eye.
the errors in observations and measurements by
using standard procedures and testing (calibrat-
ing) measuring devices. They also repeat their
measurements several times, and then find the
average value of these measurements.

It is important to distinguish between
accuracy and precision when determining
the uncertainty involved in a measurement.
Accuracy is how well a measurement conforms
to the accepted correct value for the measured
quantity, based on many careful measurements
made over a long time. Precision is a measure
of reproducibility, or how closely a series of
measurements of the same quantity agree with
one another.

SUPPLEMENT 1 S3

SUPPLEMENT

2 Reading Graphs and Maps (All Chapters)

Graphs and Maps are Important go through the same process in reverse to find a us to compare consumption of coal and natural
Visual Tools year in which oil consumption was at a certain gas during the same period.
point.
A graph is a tool for conveying information that Questions
can be summarized numerically by illustrating Questions
the information in a visual format. This informa- 1. In what year was the gap between coal use
tion, called data, is collected in experiments, sur- 1. What was the total amount of oil consumed and natural gas use the widest? In what year
veys, historical studies, and other information- in the world in 1990? was it narrowest? Describe the trend in coal
gathering activities. Graphing can be a powerful use since 1995.
tool for summarizing and conveying complex 2. In about what year between 1950 and
information, especially in the ever-expanding 2000 did oil consumption first start 2. Compare Figures 1 and 2. Among trends in
fields of environmental science. declining? oil, coal, and natural gas use, which one grew
the most sharply between 1950 and 1980?
In this textbook and accompanying web- 3. About how much oil was consumed in 2007?
based Active Graphing exercises, we use three Roughly how many times more oil was con- Likewise, we can compare many variables
major types of graphs: line graphs, bar graphs, sumed in 2007 than in 1970? How many on the same scales. Figure 3 depicts U.S. energy
and pie graphs. Here you will explore each of times more oil was consumed in 2007 than consumption for six different energy resources
these types of graphs and learn how to read in 1950? between 1980 and 2007 and projections to
them. In the web-based Active Graphing exer- 2030. It uses scales to measure time on the
cises, you can try your hand at creating some Line graphs have several important uses. x-axis and energy consumption in quadrillions
graphs. One of the most common applications is to of British thermal units (a standard unit of
compare two or more variables. For example, energy required to produce a certain amount of
Another important visual tool that can while Figure 1 shows worldwide oil consump- heat) on the y-axis.
serve the same purpose of communicating tion over a certain time period, Figure 2 enables
complex information is a map. Maps can be
used to summarize data that vary over small Y-axis Line summarizing data
or large areas—from ecosystems to the bio-
sphere, and from backyards to continents. We 4000
discuss some aspects of reading maps relating
to environmental science at the end of this Oil consumption 3000 Ordinate
supplement. (million tons)
2000
Line Graphs
1000 1970 1980 1990 2000 2010 Figure 1 World oil consump-
Line graphs usually represent data that fall Year X-axis tion, 1950–2007. (Data from U.S.
in some sort of sequence, such as a series of 0 Energy Information Administra-
measurements over time or distance. In most 1950 1960 tion, British Petroleum, Interna-
such cases, units of time or distance lie on the tional Energy Agency, and United
horizontal x-axis. The possible measurements of Abscissa Nations)
some quantity or variable, such as temperature
that changes over time or distance, usually lie 3500
on the vertical y-axis. In Figure 1, the x-axis
shows the years between 1950 and 2010, and 3000
the y-axis displays the possible values for the
annual amounts of oil consumed worldwide in Consumption 2500 Coal
millions of tons, ranging from 0 to 4,000 million (million tons of oil equivalent) 2000 Natural gas
(or 4 billion) tons. Usually, the y-axis appears on 1500
the left end of the x-axis, although y-axes can
appear on the right end, in the middle, or on 1000 1960 1970 1980 1990 2000 2010 Figure 2 World coal and natural
both ends of the x-axis. Year gas consumption, 1950–2007.
500 (Data from U.S. Energy Information
The line on a line graph, sometimes referred Administration, British Petroleum,
to as the curve, represents the measurements 0 International Energy Agency, and
taken at certain time or distance intervals. In 1950 United Nations)
Figure 1, the line represents changes in oil con-
sumption between 1950 and 2007. To find the oil
consumption for any year, find that year on the
x-axis (a point called the abscissa) and run a verti-
cal line from the axis to the consumption line.
At the point where your line intersects the con-
sumption line, run a horizontal line to the y-axis.
The value at that point on the y-axis, called the
ordinate, is the amount you are seeking. You can

S4 SUPPLEMENT 2

60 History Projected Figure 3 Energy
50 consumption by fuel
Energy consumption 40 Oil in the United States,
(quadrillion Btu) 30 1980–2007, with pro-
20 Coal jected consumption to
Natural gas 2030. (Data from U.S.
Energy Information
Administration/Annual
Energy Outlook 2007)

10 1985 1990 1995 2000 2005 2010 2015 2020 2025 Nuclear
Year Nonhydro renewables
0 Hydropower
1980
2030

Questions will end up with $1,024,000. Figure 5 shows the 2. Which one of the curves in Figure 2
difference between these two types of growth. most closely resembles the upper curve
1. Which of the energy sources has seen the in Figure 5? What, if anything, might
least growth in consumption through 2007? Questions stop that curve from becoming nearly
Which two sources are projected to have vertical?
the sharpest growth after 2020? Coal and 1. How do you think the upper curve would
hydropower are both used mostly to gener- differ if the exponential growth rate were It is important to know that line graphs can
ate electricity. The U.S. consumed about 1% instead of 10%? How would it differ if give different impressions of data, depending on
how many times as much coal as hydro- the rate were 50%? Explain why any expo- how they are designed. Changing the measure-
power in 2007? nential growth curve eventually becomes ment ranges on either of the x- or y-axes can
nearly vertical. change the shape of the curve, and two curves
2. Compare Figures 2 and 3. Has the U.S. in-
creased its use of coal and natural gas more Temperate deciduous forest
sharply or less sharply than the world as a
whole? Mean monthly temperature (°C) 30 Freezing point 350 Mean monthly precipitation (mm) Figure 4 Climate graph showing typical
20 300 variations in annual temperature (red) and
Figure 4 compares two variables—monthly 10 F MAM J J A S 250 precipitation (blue) in a temperate decidu-
temperature and precipitation (rain and snow- Month 200 ous forest.
fall) during a typical year in a temperate decidu- 0 150
ous forest. However, in this case, the variables –10 100
are measured on two different scales, so there –20 50
are two y-axes. The y-axis on the left end of the –30 0
graph shows a Centigrade temperature scale, –40 OND
while the y-axis on the right shows the range
of precipitation measurements in millimeters. J
The x-axis displays the first letters of each of the
12 month names. Thousands of dollars 1,250 $1,024,000
1,000
Questions Exponential growth
750 ($1,000 invested at 10%
1. In what month does most precipitation fall? per year interest)
What is the driest month of the year? What
is the hottest month? Linear growth
(saving $1,000
2. If the temperature curve were almost flat, per year)
running throughout the year at about its
highest point of about 30 °C, how do you 10 $70,000 Figure 5 Linear and exponential
think this forest would be different from what 0 growth. If resource use, economic
it is? (See Figure 7-15, p. 154.) If the annual 10 20 30 40 50 60 70 growth, or money invested grows
precipitation suddenly dropped and remained Year exponentially for 70 years at 10%,
under 25 centimeters all year, what do you it will increase 1,024-fold.
think would eventually happen to this forest?

Line graphs can also show dramatic differ-
ences between two types of the same phenom-
enon, such as growth. Linear growth is growth
by a given amount in each interval. Exponential
growth is growth by a fixed percentage of a
growing amount in each interval. For example,
if you save $1,000 per year under your mattress
for 70 years, you will end up with $70,000. But
if you invest $1,000 per year and earn 10% in-
terest on your total amount invested every year,
and if you keep it all invested for 70 years, you

SUPPLEMENT 2 S5

representing the same data can look quite differ- A 13
ent. For example, in Figure 6, the upper graph
shows the growth of the human population 12
from 8000 B.C. to the present, while the lower 11
graph shows human population growth between 10
1950 and 2010. The latter would be only a small
segment on the right end of the curve in the 9 Billions of people
upper graph. ?8

Questions 7

1. What would be your overall impression 6
of human population growth if you saw
only the upper graph? What would be your 5
overall impression if you saw only the lower 4
graph?
Industrial revolution 3
2. On the upper graph, mark what you would Black Death—the Plague 2
estimate to be the left and right ends of 1
the segment of the curve that fall between
1950 and 2007. Why do you think the slope 0
(steepness) of this segment varies so much
from the slope of the curve in the lower 2–5 million 8000 6000 4000 2000 2000 2100
graph? Describe the differences between the years 1970
two graphs that might explain this difference Time B. C. A. D.
in slopes.
Hunting and Agricultural revolution Industrial
3. You can see from these graphs that by ad- gathering revolution
justing a graph’s time span and the height of
its y-axis, you can change the slope of the Billions of peopleB Figure 6 Two graphs show-
curve. This can give the reader a different 8 ing human population growth.
first impression of the data. Does this make 7 1980 1990 2000 2010 The upper graph spans the time
the changed graph inaccurate or somehow 6 between 8000 B.C. and 2100
wrong? Explain. What does this tell you 5 A.D. The lower graph runs from
about what you need to look for when read- 4 1950 A.D. to 2010.
ing a graph? 3
2
It is also important to consider what aspect of 1
a data set is being displayed on a graph. The cre- 0
ator of a graph can take two different aspects of 1950 1960
one data set and create two very different look-
ing graphs that would give two different impres- Finally, but no less important, a common on the Hubbard Brook experiment in which sci-
sions of the same phenomenon. For example, scientific use of the line graph is to show experi- entists measured changes over time in the pres-
we must be careful when talking about any type mental results. Usually, such graphs represent ence of soil nutrients in a forest (the dependent
of growth to distinguish the question of whether variables, which are factors or values that can variable) in response to removal of trees from
something is growing from the question of how change. Experimenters measure changes to a the forest (the independent variable).
fast it is growing. While a quantity can keep dependent variable—a variable that changes in re-
growing continuously, its rate of growth can go sponse to changes in another variable called the On a line graph, the range of values for
up and down. independent variable. The latter may be manipu- the independent variable is usually placed
lated by experimenters in order to cause changes on the x-axis, while range of values for the
One of many important examples of growth in the dependent variable. For example, in the independent variable usually appears on the
used in this book is human population growth. Core Case Study of Chapter 2 (p. 28), we report y-axis (for example, see Figure 17-14, p. 455).
Look again at Figure 6. The two graphs in this However, another way to represent changes
figure give you the impression that human
population growth has been continuous and Average annual global growth rate (percent) 2.5
uninterrupted, for the most part. However con-
sider Figure 7, which plots the rate of growth of 2.0
the human population since 1950. Note that all
of the numbers on the y-axis, even the smallest 1.5
ones, represent growth. The lower end of the
scale represents slower growth, the higher end, 1.0
faster growth.
0.5 1970 1990 2010 2030 2050 Figure 7 Annual growth rate in
Questions world population, 1950–2007,
0.0 with projections to 2050. (Data
1. If this graph were presented to you as 1950 from U.N. Population Division and
a picture of human population growth, U.S. Census Bureau)
what would be your first impression? Do Year
you think that reaching a growth rate of
0.5% would relieve those who are con-
cerned about overpopulation? Why or why
not?

2. As the curve in Figure 7 proceeds to the right
and downward, what do you think will hap-
pen to the curve in the lower graph in Fig-
ure 6? Explain.

S6 SUPPLEMENT 2

to the independent and dependent variables is Nitrate (NO3– ) concentration 60 Figure 8 Loss of nitrate ions from a
to show them on two separate curves. This is (milligrams per liter) deforested watershed (upper curve),
useful when an experiment takes place over a 40 mostly due to precipitation wash-
long period of time, as did the Hubbard Brook ing away the nutrients, compared
experiment. In Figure 8, the years in which this Undisturbed with loss of nitrate ions from an
experiment was conducted appear on the x-axis. (control) undisturbed forest (lower curve).
The range of values for presence of a soil nutri- 20 watershed (Data from F. H. Bormann and
ent called nitrate appears on the y-axis. And two Gene Likens)
curves were plotted: one showing the values of
the dependent variable in the uncut forest (the Disturbed
control site), and the other showing the values (experimental)
of the dependent variable in the clear-cut forest watershed
(the experimental site).
1963 1964 1965 1966 1967 1968 1969 1970 1971 1972
Questions Year

1. Approximately what was the maximum net primary productivity (or NPP, a measure of 2. What is the most productive of aquatic eco-
amount of nitrate lost from the undisturbed chemical energy produced by plants in an eco- systems shown here? What is the least pro-
(control) forest? Approximately what was system) for different ecosystems, as represented ductive?
the maximum amount of nitrate lost from in Figure 9. An important application of the bar graph
the clear-cut (experimental) forest? At the
point of maximum nitrate loss from the ex- In most bar graphs, the categories to be used in this book is the age structure diagram (Fig-
perimental forest, about how many times compared are laid out on the x-axis, while the ure 10, p. S8), which describes a population by
more nitrate was lost there than in the con- range of measurements for the variable under showing the numbers of males and females in
trol forest? consideration lies along the y-axis. In our ex- certain age groups (see pp. 130–132). Environ-
ample in Figure 9, the categories (ecosystems) mental scientists are concerned about human
2. In what year do you think the experimental are on the y-axis, and the variable range (NPP) population growth, and one of the key factors
forest was cut? How long did it take, once lies on the x-axis. In either case, reading the determining a particular population’s growth
nutrient loss started there, for the losses to graph is straightforward. Simply run a line per- rate is the relative numbers of people in various
reach their maximum? How long did it take pendicular to the bar you are reading from the age categories.
for the forest to regain its pre-experimental top of that bar (or the right or left end, if it lies
level of nutrients? horizontally) to the variable value axis. In Figure In particular, the number of women of child-
9, you can see that the NPP for continental shelf, bearing age and younger gives an important clue
Bar Graphs for example, is close to 1,600 kcal/m2/yr. to whether the population might grow rapidly.
If most of the women fall into that category, the
The bar graph is used to compare measurements Questions population will grow much more quickly than
for one or more variables across categories. Un- it would if most of the women are beyond their
like the line graph, a bar graph typically does 1. About how many times greater is the NPP child-bearing years. Likewise, a population with
not involve a sequence of measurements over in a tropical rain forest than the NPP in a most of its women beyond childbearing age will
time or distance. The measurements compared savannah? likely shrink in future years.
on a bar graph usually represent data collected
at some point in time or during a well-defined
period. For instance, we can compare the

Terrestrial Ecosystems Figure 9
Swamps and marshes
Tropical rain forest Estimated annual
Temperate forest
average net pri-
Northern coniferous forest (taiga)
Savanna mary productivity

Agricultural land (NPP) in major
Woodland and shrubland
life zones and
Temperate grassland
Tundra (arctic and alpine) ecosystems,

Desert scrub expressed as
Extreme desert
Aquatic Ecosystems kilocalories of

Estuaries energy produced
Lakes and streams
Continental shelf per square meter

Open ocean per year (kcal/m2/

yr). (Data from

R. H. Whittaker,

Communities and

Ecosystems, 2nd

800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 ed., New York:

Average net primary productivity (kcal/m2/yr) Macmillan, 1975)

SUPPLEMENT 2 S7

Note that in Figure 10, the bars are placed Developing Countries Developed Countries
horizontally and run both left and right from
the center. This allows comparison of two parts 85+ Male Female 85+ Male Female
of the population across age groups. In this case, 80–85 80–85
values for males lie to the left and values for Population in billions 75–79 75–79
females lie to the right of the y-axis. The figure Age 70–74 70–74
contains two separate graphs, one for developing Age65–69 65–69
countries and the other for developed countries. 60–64 60–64
55–59 55–59
Questions 50–54 50–54
45–49 45–49
1. What are the three largest age groups in 40–44 40–44
developing countries? What are the three 35–39 35–39
largest age groups in developed countries? 30–34 30–34
Which group of countries will likely grow 25–29 25–29
more rapidly in coming years? 20–24 20–24
15–19 15–19
2. If all girls under the age of 15 had only one 10–14 10–14
child during their lifetimes, how do you think
these structures would change over time? 5–9 5–9
0–4 0–4
Another interesting application of the bar
graph is called a stacked bar graph. In such a 300 200 100 0 100 200 300 300 200 100 0 100 200 300
graph, each bar is actually a combination of
several smaller bars representing multiple data Population (millions) Population (millions)
groups, stacked up to make one bar divided by
different colors or shades to depict the sub- Figure 10 Population structure by age and sex in developing countries and developed countries, 2006. (Data
groups. Figure 11 is a good example of this, from United Nations Population Division and Population Reference Bureau)
combining population data for six different
regions of the world. Each bar contains six dif- Pie Graphs Figure 15-3 (p. 373) shows this and other
ferent sets of data, all collected in, or projected data in more detail, and illustrates how pie
for, a particular year. This bar graph is a power- Like bar graphs, pie graphs illustrate numeri- graphs can be used to compare different groups
ful illustration of comparative growth rates of cal values for two or more categories. But of categories and different data sets. Also, see
the human populations in the various regions, in addition to that, they can also show each the Active Graphing exercise for Chapter 15 on
and it effectively shows the cumulative effects category’s proportion of the total of all measure- the website for this book.
of growth. ments. Usually, the categories are ordered on
the graph from largest to smallest, for ease of Questions
Questions comparison, although this is not always the case.
Also, as with bar graphs, pie graphs are generally 1. Do you think that the fact that use of natural
1. Which region will likely grow the fastest be- snapshots of a set of data at a point in time or gas, coal, and oil have all grown over the
tween 2010 and 2050? Which region’s popu- during a defined time period. Unlike line graphs, years (see Figures 1 and 2, p. S4) means that
lation will likely stay about the same size? one pie graph cannot show changes over time. other categories on this graph have shrunk
in that time? Explain.
2. About what proportion of the world’s popu- For example, Figure 12 shows how much
lation lived in Asia, Oceania, Africa, and each major energy source contributes to the 2. Use the projected data in Figure 3 (p. S5)
Europe (the eastern hemisphere) and what world’s total amount of energy used in 2006. to estimate how the relative sizes of the pie
proportion lived in North America, Latin This graph includes the numerical data used to slices for each energy resource might change
America, and the Caribbean (the western construct it—the percentages of the total taken by 2030.
hemisphere) in 2005? How will these pro- up by each part of the pie. But pie graphs can be
jected proportions change, if at all, by 2050? used without the numerical data included, and Reading Maps
such percentages can be estimated roughly. The
pie graph thereby provides a generalized picture Maps can be used for considerably more than
of the composition of a set of data. showing where places are relative to one an-
other. They can also show comparisons among

9
North America

8 Latin America and the Caribbean
Europe

7 Sub-Saharan Africa
North Arica/West Asia

6 Asia (excl. W. Asia) and Oceania

5

4

3

2

1

Figure 11 Projected world population 0 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
growth, by region. (Data from United 1950 2005
Nations)
Year

S8 SUPPLEMENT 2

Nuclear power Figure 12 World energy use by source in 2006.
6% Geothermal, (Data from U.S. Department of Energy, British
solar, wind Petroleum, Worldwatch Institute, and Inernational
2.5% Energy Institute)

Hydropower Deaths per 100,000 adults per year
4.5%

RENEWABLE 18% <1 1–5 5–10 10–20 20–30 30+ Figure 13 Prema-
NONRENE ture deaths from
Natural gas air pollution in
21% the United States,
mostly from very
Coal Biomass small particles
22% 11% added to the at-
mosphere by coal-
WABLE 82% Oil burning power
33% plants. (Data from
U.S. Environmen-
tal Protection
Agency)

different areas with regard to any number of air pollution in the various regions of the coun- similarities between the maps in Figures 13
factors or conditions. This is the basis for the try. Figure 14 compares various regions of the and 14? If so, what are they?
field of geographical information systems (GIS, country in terms of levels of acidity in precipita-
see Figure 3-23, p. 73). Using powerful GIS tools, tion. Study these figures and their captions. The Active Graphing exercises available for
scientists can create detailed maps that show various chapters on the website for this textbook
where natural resources are concentrated, for Questions will help you to apply this information. Register
example, within a given region or in the world. and log on to CengageNOW™ using the access
1. Generally, what part of the country has code card in the front of your book. Choose a
In environmental science, such maps can be the lowest level of premature deaths due chapter with an Active Graphing exercise, click
very helpful. For example, maps can be used to to air pollution? What part of the country on the exercise, and begin learning more about
compare how people or different areas are affect- has the highest level? What is the level graphing. There is also a data analysis exercise
ed by environmental problems such as air pollu- in the area where you live or go to school? at the end of each chapter in this book. Some of
tion and acid deposition (a form of air pollution). these exercises involve analysis of various types
Figure 13 is a map of the United States showing 2. Generally, what part of the country has the of graphs and maps.
the relative numbers of premature deaths due to highest levels of acidity in its precipitation?
What area has the lowest? Do you see any

5.2

5.2 5.4 5.3 4.8
5.3 5.6 5.3
5.5 5.6 5.3
5.3
5.5 5.6 4.8

5.8 5.4 4.8 5.1 4.7 4.8 4.8 4.8
5.8 5.2 4.9 4.9

5.4 5.4 5.4 5.7 5.2 5.3 5.0 4.8 4.8
5.3 4.7
5.1 4.8 4.7 4.7
5.7 4.7 4.5
5.4 5.4 5.2 5.0 4.8 4.5 4.6 4.5
5.5 5.6 5.2 5.4 5.6 5.1 4.8 4.5 4.6
4.6 4.5 4.6
5.0 4.9 4.7 4.8 4.7

5.4 5.4 5.2 4.9 4.6 4.4 4.5 4.6 Figure 14 Measure-
5.5 6.4 5.3 ments of the pH of pre-
5.4 4.4 4.4 cipitation at various sites
4.6 4.7 4.5 4.4 4.5 4.7 4.4 in the lower 48 states
6.2 5.8 5.6 5.8 5.4 in 2005 as a result of
5.2 6.1 5.8 4.8 4.7 4.6 4.3 4.5 4.5 4.5 4.6 4.7 acid deposition, mostly
5.5 5.8 5.3 5.1 5.0 4.6 4.6 4.5 4.4 4.7 from a combination of
motor vehicles and coal
5.4 5.0 5.6 4.8 4.4 4.5 4.6 burning power plants
5.5 5.2 4.7 4.5 4.6 4.5 (red dots). The pH is a
5.4 5.4 Lab pH measure of acidity; the
5.2 5.1 5.1 5.6 5.3 4.9 4.7 4.6 4.5 lower the pH, the higher
4.9 4.7 4.6 4.6 4.6 4.8 4.7 ≥ 5.3 the acidity. For more
details see Figure 5,
5.4 5.1 5.3 4.9 4.5 4.6 4.7 4.7 4.7 5.2–5.3 p. S41, in Supplement 6.
5.2 5.9 5.3 5.0 4.6 4.9 5.1–5.2 (Data from National
5.2 5.0 5.0–5.1 Atmospheric Deposition
5.1 4.9 4.7 4.6 4.6 Program/National Trends
Network, 2006)
5.3 5.2 5.5 4.7 4.7

4.7 4.9–5.0
4.8–4.9
5.1 4.8 4.8 4.8 4.7–4.8
4.8 4.6–4.7
5.3 5.4 4.9 4.8 4.7 4.5–4.6
5.4 5.0 4.6 4.7
4.9
4.9 4.9 4.8
4.8
4.7

5.2 4.4–4.5
5.2 4.9 4.3–4.4

5.1 < 4.3

SUPPLEMENT 2 S9

SUPPLEMENT

3 Economic, Population, Hunger, Health,
and Waste Production Data and Maps

Figure 1 Countries of the world. GREENLAND

Map Analysis:

1. What is the largest country (in
area) in (a) North America, (b)
Central America, (c) South America,
(d) Europe, and (e) Asia?

2. What countries surround (a) China,
(b) Mexico, (c) Germany, and
(d) Sudan?

CANADA I

NORTH AMERICA GAM
GUINEA-B
UNITED STATES OF AMERICA
SI
BAHAMAS

MEXICO CUBA DOMINICAN
REPUBLIC
JAMAICA HAITI
BELIZE PUERTO RICO

GUATEMALA HONDURAS
EL SALVADOR NICARAGUA

70 COSTA RICA TRINIDAD &
PANAMA TOBAGO
60
Gross world product VENEZUELA
(trillion 2006 dollars)50
COLOMBIA
FRESNGUCRUIHYNAGANUIMAANA40ECUADOR

30 SOUTH AMERICA

20 PERU BRAZIL
BOLIVIA
10
1970 1975 1980 1985 1990 1995 2000 2005 2010 PARAGUAY
Year
CHILE
Figure 2 Gross world product, 1950–2006. (Data from International
Monetary Fund and the World Bank) URUGUAY
Data and Graph Analysis
1. Roughly how many times bigger than the gross world product of ARGENTINA

1985 was the gross world product in 2006? FALKLAND/MALVINAS
2. If the current trend continues, about what do you think the gross ISLANDS

world product will be in 2010, in trillions of dollars?

S10 SUPPLEMENT 3#

(Chapters 1, 6)

CELAND

SWEDEN FINLAND

NORWAY RUSSIA

ESTONIA

E U R O P EDENMARK LITHUALNAIATVIA ASIA

UNITED BELARUS
KINGDOM

IRELAND NETHERLANDS POLAND
PORTUGAL GERMANY

BELGIUM CZECH

LUXEMBOURG REP. SLOVAKIA UKRAINE KAZAKHSTAN

SWITZERLAND AUSTRIA HUNGARY MOLDOVA

SLOVECNRIAOATIA ROMANIA MONGOLIA

FRANCE

BOSNIA-HERZEGIOTAAVLILNYBAANIAMYGURAGECEOECDSELOBAUNVLIIAGAARIA GEORGIA KYRGYZSTAN NORTH
ARMENIA AZERBAIJAN KOREA
SPAIN UZBEKISTAN

TURKEY TURKMENISTAN TAJIKISTAN

SYRIA SOUTH KOREA JAPAN

CYPRUS

TUNISIA LEBANON AFGHANISTAN CHINA
PAKISTAN
MOROCCO ISRAEL IRAQ IRAN

WESTERN JORDAN KUWAIT
SAHARA
QATAR NEPAL
UNITED
ALGERIA SAUDI ARAB BHUTAN
ARABIA
LIBYA EGYPT EMIRATES

INDIA BANGLADESH TAIWAN
MYANMAR HONG KONG
LAOS
MAURITANIA OMAN

MALI NIGER CHAD

SENEGAL ERITREA YEMEN THAILAND VIETNAM PHILIPPINES

MBIA BURKINA AFRICA SUDAN
BISSAU FASO
CAMBODIA
GHANA
GUINEA NIGERIA
IVORY
ERRA LEONE COAST CENTRAL ETHIOPIA
LIBERIA AFRICAN
TBEONGION CAMEROON REPUBLIC SRI
LANKA
BRUNEI
UGANDA SOMALIA MALAYSIA
DEMOCRATIC
EQUATORIAL REPUBLIC OF KENYA

GUINEA CONGO CONGO

GABON

RAWANDA PAPUA
BARUNDI NEW
GUINEA
TANZANIA

INDONESIA

ANGOLA SOLOMON
ISLANDS
MALAWI
ZAMBIA VANUATU

MOZAMBIQUE NEW CALEDONIA

FIJI

NAMIBIA ZIMBABWE MADAGASCAR MAURITIUS

BOTSWANA RÉUNION

SWAZILAND AUSTRALIA

LESOTHO
SOUTH AFRICA

NEW
ZEALAND

High-income: $10,800 or more

Upper middle-income: $3,500–$10,799

Lower middle-income: $900–$3,499

Figure 3 High-income, upper middle-income, lower Low-income: $899 or less No data available
middle-income, and low-income countries in terms of
gross national income (GNI) PPP per capita (U.S. dol- Year Event Human
lars) in 2006. (Data from World Bank and International population
Monetary Fund) 1.2 million
4 million
Data and Map Analysis 50,000 B.C. Hunter-gatherer societies 5 million
10,000 B.C. End of last Ice Age
1. In how many countries is the per capita average Agricultural Revolution 100 million
income $899 or less? Look at Figure 1 and find the 8,000 B.C. Contraceptives in use in Egypt 250 million
names of three of these countries. 2,000 B.C.
450 million
2. In how many instances does a lower-middle- or low- 500 B.C. 791 million
income country share a border with a high-income 1,000 A.D.
country? Look at Figure 1 and find the names of the 1 billion
countries involved in three of these instances.
2 billion
1347–1351 Black Death (Plague); 75 million people die
3 billion
1500 4 billion
5 billion
1750 Industrial Revolution begins in Europe 6 billion
7 billion
1800 Industrial Revolution begins in the United States 8 billion
9 billion
1804

1845–1849 Irish potato famine: 1 million people die

1927

1943 Penicillin used against infection

1952 Contraceptive pill introduced

1957 Great famine in China; 20 million die

1961

Figure 4 Population timeline, 10,000 B.C.–2008. 1974 Projected human population:
1984 Projected human population:
Data Analysis 1987 Projected human population:
2011
1. About how many years did it take the human 2024
population to reach 1 billion? How long after 2042
that did it take to reach 2 billion?

2. In about what year was the population half of
what it is projected to be in 2011?

S12 SUPPLEMENT 3

Average annual global growth rate (percent) 2.5 Figure 5 Annual growth rate in world population, 1950–2007 with
projections to 2050. (Data from U.N. Population Division and U.S.
Census Bureau

2.0 Data and Graph Analysis

1. In about what year since 1950 did the growth rate first start in-

1.5 creasing? In about what year did it first start decreasing?
2. In about what year will the growth rate reach half of what it was

at its peak since 1950, according to projections?

1.0

0.5

0.0 1970 1990 2010 2030 2050
1950

Year

Figure 6 Rate of population increase (%) in 2007. High: Greater than 2%
(Data from Population Reference Bureau and United Moderate: 1–1.99%
Nations Population Division) Low: 0.3–0.9%
Static: less than 0.3% or declining
Data and Map Analysis

1. What continent holds the highest number of coun-
tries with high rates of population increase? What
continent has the highest number of countries with
static rates? (See Figure 1 on pp. S10–S11 for coun-
try and continent names.)

2. For each category on this map, name the two coun-
tries that you think are largest in terms of total area?

SUPPLEMENT 3 S13

Figure 7 Total fertility rate for the world, developed regions, and 8
less developed regions, 1950–2007, with projection to 2050 (based
on medium population projections). (Data from U.N. Population Total fertility rate 7 Developing
Division) (children per woman) countries

Data and Graph Analysis 6

1. What are two conclusions you can draw from comparing these 5 World
curves?
4
2. In 2010, about how many more children will be born to each
woman in the developing regions than will be born to each Developed
woman in the developed regions? 3 countries

2

1 1990 2010 2030 2050
1955 1970

Year

1.1–1.9 2.0–2.9 3.0–3.9 4.0–5.9 6.0–8.1

Figure 8 Total fertility rate (TFR), or average number of children born to the
world’s women throughout their lifetimes, as measured in 2007. (Data from
Population Reference Bureau and United Nations Population Division)

Data and Map Analysis
1. Which country in the highest TFR category borders two countries in the

lowest TFR category? What are those two countries? (See Figure 1 on
pp. S10–S11.)
2. Describe two geographic patterns that you see on this map.

S14 SUPPLEMENT 3

Infant mortality rate 200 Figure 9 Infant mortality rate for the world, developed regions, and
(deaths per 1,000 live births) less developed regions, 1950–2007, with projection to 2050 (based
Developing on medium population projections). (Data from United Nations
countries Population Division)
150
Data and Graph Analysis
100
World 1. What are two conclusions you can draw from comparing these
curves?
Developed
50 countries 2. When the world infant mortality was 100 deaths per 1,000 live
births, what were the approximate infant mortality rates for
developed and developing regions?

0
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

Year

2–9 10–19 20–49 50–99 100–200 No data

Figure 10 Infant mortality rate in 2007. (Data from Population Reference
Bureau and United Nations Population Division)
Data and Map Analysis
1. Describe a geographic pattern that you can see, related to infant mortality

rates as reflected on this map.
2. Describe any similarities that you see in geographic patterns between this

map and the one in Figure 8.

SUPPLEMENT 3 S15

0.4–10 11–100 101–200 201–1,000 1,001–25,100 No data

Figure 11 Population density per square kilometer in 2007. (Data from
Population Reference Bureau and United Nations Population Division)

Data and Map Analysis

1. What is the country with the densest population? (See Figure 1 on
pp. S10–S11 for country and continent names.)

2. List the continents in order from the most densely populated, overall,
to the least densely populated, overall.

5

World

4

Figure 12 Urban population totals and projections for the world, Urban population 3
for developing countries, and for developed countries, 1950–2007 (billions)
with projections to 2030 (Data from United Nations Population Developing
Division) 2 countries

Data and Graph Analysis 1
Developed
1. In about what year did the urban population in developing coun- countries
tries surpass the urban population in developed countries? In
about what year was the former twice that of the latter? 0
1950 1960 1970 1980 1990 2000 2010 2020 2030
2. About how many people will be living in urban areas in develop-
ing countries in 2030? In 2030, about how many people will be Year
living in a developing country urban area for every person living in
a developed country urban area?

S16 SUPPLEMENT 3

Percentage of Countries with the Most Undernourished People
population
undernourished, Democratic Republic 35.5 million
2005 of the Congo

0%–5% Bangladesh 42 million

5%–20% China 142 million

20%–35% India 221 million

>35%

Figure 13 World hunger shown as a percentage of
population suffering from chronic hunger and mal-
nutrition in 2005. (Data from Food and Agriculture
Organization, United Nations)
Data and Map Analysis
1. List the continents in order from the highest per-

centage of undernourished people to the lowest
such percentage. (See Figure 1 on pp. S10–S11
for country and continent names.)
2. On which continent is the largest block of coun-
tries that suffer the highest levels of undernour-
ishment? List five of these countries.

SUPPLEMENT 3 S17

Adult prevalence rate
<0.1%
0.1– <0.5%
0.5– <1.0%
1.0– <5.0%
5.0– <15.0%
15.0–34.0%
Data not included

Figure 14 Percentage of adults infected with HIV in 2005. (Data from the
World Health Organization)

Data and Map Analysis

1. How many countries have an adult HIV prevalence rate of 5% or higher?
List ten of these countries. (See Figure 1 on pp. S10–S11 for country and
continent names.)

2. Find an instance where a country with a high rate of HIV prevalence bor-
ders a country or countries with a low rate. List the countries involved.

Figure 15 Total and per capita production of municipal solid waste 250 2.5
in the United States, 1960–2005. (Data from the U.S. Environmental Total
Protection Agency) Total municipal solid waste
(million tons per year) 200 Per capita Per capita generation
Data and Graph Analysis 2.0 (kilograms/person/day)

1. How much more municipal solid waste was generated in 2005 150
than in 1960, in millions of tons?

2. In what year did per capita solid waste generation reach a level
four times as high as it was in 1960?

1.5
100

50 1.0
1960 1970 1980 1990 2000 2003 2004 2005

Year

S18 SUPPLEMENT 3

Municipal solid waste recycled 80 Total amount 50 Percentage of solid waste recycled Figure 16 Total amount and percent of municipal solid waste
(million tons) 70 recycled 45 recycled in the United States, 1960–2005. (Data from the U.S.
60 40 Environmental Protection Agency)
50
40 35 Data and Graph Analysis
30
20 30 1. After 1980, how long did it take for the United States to triple
10 the total amount of materials recycled in 1980?
25
0 2. In what 10-year period was the sharpest increase in the per-
1960 centage of solid waste recycled in the United States?

% recycled 20
15

10

1970 1980 1990 5
Year 2000 2005

Afghanistan North Korea
Iraq Timor-Leste

Pakistan

Haiti Chad Bangladesh
Myanmar
Sudan

Guinea Nigeria Ethiopia
Ivory Coast
Somalia

Central African Uganda
Republic Barundi

Democratic Zimbabwe
Republic of
the Congo

Figure 17 Top 20 failing states in 2006. According to a 2007 study by
International Alert, 56 countries could become failing or failed states dur-
ing this century as a result of conflict and instability caused by projected
climate change. (Data from the U.S. Central Intelligence Agency, Carnegie
Endowment for International Peace, and Fund for Peace)

SUPPLEMENT 3 S19

SUPPLEMENT

4 Biodiversity, Ecological Footprints,
and Environmental Performance Maps

Figure 1 Composite satellite view of the earth showing its major terrestrial
and aquatic features.

Data and Map Analysis

1. On what continent does desert make up the largest percentage of the
continent’s total land area?

2. Which two continents contain large areas of polar ice?

S20 SUPPLEMENT 4

(Chapters 1, 3–9)

SUPPLEMENT 4

S21 NASA Goddard Space Flight Center Image by Reto Stöcki (land surface, shallow water, clouds).
Enhancements by Robert Simmon (ocean color, compositing, 3D globes, animation)

Figure 2 Global map of plant biodiversity. (Used by permission
from Kier, et al. 2005. “Global Patterns of Plant Diversity and
Floristic Knowledge.” Journal of Biogeography, Vol. 32, Issue 6,
pp. 921–1106, and Blackwell Publishing)

Data and Map Analysis

1. What continent holds the largest continuous area of land that
hosts more than 5,000 species per eco-region? On what con-
tinent is the second largest area of such land? (See Figure 1,
pp. S10–S11, in Supplement 3 for the names of countries and
continents.)

2. Of the six categories represented by six different colors on this
map, which category seems to occupy the most land area in
the world (not counting Antarctica, the large land mass on the
bottom of the map, and Greenland)?

Species number
per ecoregion

<500
500–1000
1000–2000
2000–3000
3000–5000
>5000

S22 SUPPLEMENT 4

SUPPLEMENT 4 S23

Image not available due to copyright restrictions

S24 SUPPLEMENT 4

SUPPLEMENT 4 S25

Ecological Reserve

<50% of biocapacity

>50% of biocapacity

Ecological Deficit

>50% of biocapacity

<50% of biocapacity

Insufficient data

Figure 4 Ecological Debtors and Creditors. The ecological footprints of some
countries exceed their biocapacity, while others still have ecological reserves.
(Data from Global Footprint Network)
Data and Map Analysis
1. List five countries, including the three largest, in which the ecological

deficit is greater than 50% of biocapacity. (See Figure 1, pp. S10–S11, in
Supplement 3 for names of countries and continents.)
2. On which two continents does land with ecological reserves of more than
50% of biocapacity occupy the largest percentage of total land area? Look
at Figure 3 and for each of these two continents, list the highest human
footprint value that you see on the map.

S26 SUPPLEMENT 4

Figure 5 Natural capital: biomes of
North America.

Data and Map Analysis

1. What type of biome occupies the
most coastal area?

2. Which biome is the rarest in North
America?

North American Biomes
Tundra
Mountain zone
Mountain forest
Taiga
Temperate deciduous forest
Tropical forest
Temperate grassland
Chaparral
Desert
Semidesert

Figure 6 Gross primary productivity across the continental United
States, based on remote satellite data. The differences roughly
correlate with variations in moisture and soil types. (NASA’s Earth
Observatory)

Data and Map Analysis

1. Comparing the five northwestern-most states with the five
southeastern-most states, which of these regions has the
greater variety of levels of gross primary productivity? Which
of the regions has the highest levels, overall?

2. Compare this map with that of Figure 5. Which biome in the
United States is associated with the highest level of gross pri-
mary productivity?

0 0.1 4.5 8.6 12.6 16.7 20.8 24.9 28.9 32.9

Gross primary productivity
(grams of carbon per square meter)

SUPPLEMENT 4 S27

Image not available due to copyright restrictions

S28 SUPPLEMENT 4

Image not available due to copyright restrictions

SUPPLEMENT 4 S29

88.1–78.6 78.5–69.5 69.4–60.1 60.0–51.1 51.0–25.7 No data

Figure 8 2006 Environmental Performance Index (EPI) uses 16 indicators of
environmental health, air quality, water resources, biodiversity and habitat
quality, renewable natural resources, and sustainable energy resources to
evaluate countries in terms of their ecosystem health and environmental
stresses on human health. This map shows the scores by quintiles. (Data from
Yale Center for Environmental Law and Policy and the Center for International
Earth Science Information Network)

Data and Map Analysis
1. List six countries that lie within the highest EPI range. List six countries

that lie within the lowest EPI range. (See Figure 1, pp. S10–S11, in Supple-
ment 3 for country names.)
2. Name a country in the 78.5–69.5 quintile that is completely surrounded by
countries in lower quintiles?

S30 SUPPLEMENT 4

Environmental History SUPPLEMENT
(Chapters 1, 2, 5, 7, 8)
5

S5-1 A Look at Some Past The Sumerian Civilization replenished very slowly and were highly suscep-
Collapsed Because tible to water and wind erosion when protective
Civilizations of Unsustainable Farming vegetation was removed for growing crops and
grazing livestock. Within a few decades, the set-
The Norse Greenland By around 4000 B.C., a highly advanced urban tlers degraded much of this natural capital that
Civilization Destroyed Its and literate Sumerian civilization had begun had taken thousands of years to build up.
Resource Base emerging on the flood plains of the lower
reaches of the Tigris and Euphrates Rivers in When the settlers realized what was hap-
Greenland is a vast and mostly ice-covered parts of what is now Iraq. This civilization devel- pening, they took corrective action to save the
island about three times the size of the U.S. state oped science and mathematics and built a well- remaining trees, and they stopped raising eco-
of Texas. During the 10th century, Viking ex- engineered crop irrigation system, which used logically destructive pigs and goats. The farmers
plorers settled a small, flat portion of this island dams to divert water from the Euphrates River joined together to slow soil erosion and preserve
that was covered with vegetation and located through a network of gravity-fed canals. their grasslands. They estimated how many
near the water. sheep the communal highland grasslands could
The irrigated cropland produced a food sustain and divided the allotted quotas among
In his 2005 book, Collapse: How Societies Choose surplus and allowed Sumerians to develop the themselves.
to Fail or Succeed, biogeographer Jared Diamond world’s first cities and written language (the
describes how this 450-year-old Norse settle- cunneiform script). But the Sumerians also Icelanders also learned how to fish, how to
ment in Greenland collapsed in the 1400s from a learned the painful lesson that long-term irriga- tap into an abundance of hot springs and heated
combination of colder weather in the 1300s and tion can lead to salt buildup in soils and sharp rock formations for geothermal power, and
abuse of its soil resources. declines in food production. how to use hydroelectric power from the many
rivers. Renewable hydropower and geothermal
Diamond suggests the Norse made three ma- Poor underground drainage slowly raised the energy provide about 95% of the country’s
jor errors. First, they cut most of the trees and water table to the surface, and evaporation of electricity, and geothermal energy is used to
shrubs to clear fields, make lumber, and gather the water left behind salts that sharply reduced heat 80% of its buildings and to grow most of its
firewood. Without that vegetation, cold winds crop productivity—a form of environmental fruits and vegetables in greenhouses.
dried and eroded the already thin soil. The degradation we now call soil salinization (Fig-
second error was overgrazing, which meant the ure 12-14, p. 289). As wheat yields declined, the In terms of per capita income, Iceland is one
depletion of remaining vegetation and trampling Sumerians slowed the salinization by shifting of the world’s ten richest countries, and in 2006
of the fragile soil. to more salt-tolerant barley. But as salt con- it had the world’s fifth highest Environmental
centrations continued to increase, barley yields Sustainability Index. By 2050, Iceland plans to
Finally, when wood used for lumber was declined and food production was undermined. become the world’s first country to run its entire
depleted, the Norse removed chunks of their economy on renewable hydropower, geothermal
turf and used it to build thick walls in their hous- Around 2000 B.C., this once-great civilization energy, and wind, and to use these resources to
es to keep out cold winds. Because they removed disappeared as a result of such environmental produce hydrogen for running all of its motor
the turf faster than it could be regenerated, there degradation, along with economic decline and vehicles and ships (see Chapter 16 Core Case
was less land for grazing so livestock numbers invasion by Semitic peoples. Study, p. 399).
fell. As a result, their food supply and civilization
collapsed. Archeological evidence suggests the Iceland Has Had Environmental THINKING ABOUT
last residents starved or froze to death. Struggles and Triumphs Past Civilizations

After about 500 years, nature healed the Iceland is a Northern European island country What are two ecological lessons that we could
ecological wounds that the Norse had caused, slightly smaller than the U.S. state of Kentucky. learn from these three stories?
and Greenland’s meadows recovered. In the This volcanic island is located in the North
20th century, Danes who settled in Greenland Atlantic Ocean just south of the Arctic Circle S5-2 An Overview of
reintroduced livestock. Today, more than 56,000 between Greenland and Norway, Ireland, and U.S. Environmental
people make their living there by mining, fish- Scotland. Glaciers cover about 10% of the coun- History
ing, growing crops, and grazing livestock. try, and it is subject to earthquakes and volcanic
activity. There Have Been Four Major Eras
But there is evidence that Greenland’s green of U.S. Environmental History
areas—about 1% of its total land area—are Immigrants from Scandinavia, Ireland, and
again being overused and strained to their limits. Scotland began settling the country during the The environmental history of the United States
Now Greenlanders have the scientific knowl- late 9th and 10th centuries A.D. Since these set- can be divided into four eras. During the tribal
edge to avoid the tragedy of the commons by tlements began, most of the country’s trees and era, 5–10 million tribal people (now called
reducing livestock numbers to a sustainable other vegetation have been destroyed and about Native Americans) occupied North America for
level, cutting trees no faster than they can be half of its original soils have eroded into the sea. at least 10,000 years before European settlers
replenished, and practicing soil conservation. As a result, Iceland suffers more ecological deg- began arriving in the early 1600s. These hunter–
radation than any other European country. gatherers generally had sustainable, low-impact
Because of global warming, some of the ice ways of life because of their low numbers and
that covers most of Greenland is melting (Fig- The early settlers saw what appeared to be a low resource use per person.
ure 19-C, p. 508). This may increase agricultural country with deep and fertile soils, dense forests,
activity and extraction of mineral and energy and highland grasslands similar to those in their
resources. Time will tell what beneficial and native countries. They did not realize that the
harmful environmental effects such changes soils built up by ash from volcanic eruptions were
will bring.

SUPPLEMENT 5 S31

Next was the frontier era (1607–1890) In 1864, George Perkins Marsh, a
when European colonists began settling North scientist and member of Congress from
America. Faced with a continent offering seem- Vermont, published Man and Nature, which
ingly inexhaustible resources, the early colonists helped legislators and citizens see the need
developed a frontier environmental world- for resource conservation. Marsh ques-
view. They saw a wilderness to be conquered tioned the idea that the country’s resources
and managed for human use. were inexhaustible. He also used scientific
studies and case studies to show how the
Next came the early conservation era (1832– rise and fall of past civilizations were linked
1870), which overlapped the end of the frontier to the use and misuse of their soils, water
era. During this period some people became supplies, and other resources. Some of his
alarmed at the scope of resource depletion and resource conservation principles are still
degradation in the United States. They argued used today.
that part of the unspoiled wilderness on public
lands should be protected as a legacy to future What Happened between
generations. Most of these warnings and ideas 1870 and 1930?
were not taken seriously.
Between 1870 and 1930, a number of
This period was followed by an era—
lasting from 1870 to the present—featuring an actions increased the role of the federal
increased role of the federal government and
private citizens in resource conservation, public government and private citizens in resource
health, and environmental protection.
conservation and public health (Figure 2).
The Frontier Era (1607–1890)
The Forest Reserve Act of 1891 was a turning
During the frontier era, European settlers spread
across the land, cleared forests for cropland and point in establishing the responsibility of
settlements, and displaced the Native Americans
who generally had lived on the land sustainably the federal government for protecting pub- Figure 1 Henry David Thoreau (1817–1862) was an
for thousands of years. lic lands from resource exploitation. American writer and naturalist who kept journals about
his excursions into wild areas in parts of the northeast-
The U.S. government accelerated this set- In 1892, nature preservationist and ern United States and Canada and at Walden Pond in
tling of the continent and use of its resources by activist John Muir (1838–1914)(Figure 3) Massachusetts. He sought self-sufficiency, a simple life-
transferring vast areas of public land to private founded the Sierra Club. He became the style, and a harmonious coexistence with nature.
interests. Between 1850 and 1890, more than leader of the preservationist movement, which
half of the country’s public land was given away called for protecting large areas of wilder-
or sold cheaply by the government to railroad,
timber, and mining companies, land developers, ness on public lands from human exploita-
states, schools, universities, and homesteaders
to encourage settlement. This era came to an tion, except for low-impact recreational
end when the government declared the frontier
officially closed in 1890. activities such as hiking and camping. This idea Early in the 20th century, the U.S. conser-

Early Conservationists (1832–1870) was not enacted into law until 1964. Muir also vation movement split into two factions over

Between 1832 and 1870, some people became proposed and lobbied for creation of a national how public lands should be used. The wise-use,
alarmed at the scope of resource depletion and
degradation in the United States. They urged the park system on public lands. or conservationist, school, led by Roosevelt and
government to preserve part of the unspoiled
wilderness on public lands owned jointly by all Mostly because of political opposition, effec- Pinchot, believed all public lands should be
people (but managed by the government) and to
protect it as a legacy to future generations. tive protection of forests and wildlife did not be- managed wisely and scientifically to provide

Two of these early conservationists were gin until Theodore Roosevelt (Figure 4, p. S34), needed resources. The preservationist school, led
Henry David Thoreau (1817–1862) and George
Perkins Marsh (1801–1882). Thoreau (Figure 1) an ardent conservationist, became president. His by Muir wanted wilderness areas on public lands
was alarmed at the loss of numerous wild spe-
cies from his native eastern Massachusetts. To term of office, 1901–1909, has been called the to be left untouched. This controversy over use
gain a better understanding of nature, he built
a cabin in the woods on Walden Pond near country’s Golden Age of Conservation. of public lands continues today.
Concord, Massachusetts, lived there alone for
2 years, and wrote Life in the Woods, an environ- While in office he persuaded Congress to give In 1916, Congress passed the National
mental classic.*
the president power to designate public land as Park Service Act. It declared that parks are to
*I (Miller) can identify with Thoreau. I spent 10 years
living in the deep woods studying and thinking about federal wildlife refuges. In 1903, Roosevelt es- be maintained in a manner that leaves them
how nature works and writing early editions of the
book you are reading. I lived in a remodeled school bus tablished the first federal refuge at Pelican Island unimpaired for future generations. The act also
with an attached greenhouse. I used it as a scientific
laboratory for evaluating things such as passive and off the east coast of Florida for preservation established the National Park Service (within
active solar energy technologies for heating the bus
and water, waste disposal (composting toilets), natural of the endangered brown pelican (Photo 1 in the Department of the Interior) to manage the
geothermal cooling (earth tubes), ways to save energy
and water, and biological control of pests. It was great the Detailed Contents), and he added 35 more system. Under its first head, Stephen T. Mather
fun and I learned a lot. In 1990, I came out of the woods
to find out more about how to live more sustainably in reserves by 1904. He also more than tripled the (1867–1930), the dominant park policy was to
urban areas, where most people live.
size of the national forest reserves. encourage tourist visits by allowing private con-

In 1905, Congress created the U.S. Forest cessionaires to operate facilities within the parks.

Service to manage and protect the forest reserves. After World War I, the country entered a

Roosevelt appointed Gifford Pinchot (1865– new era of economic growth and expansion.

1946) as its first chief. Pinchot pioneered scien- During the Harding, Coolidge, and Hoover ad-

tific management of forest resources on public ministrations, the federal government promoted

lands. In 1906, Congress passed the Antiquities increased sales of timber, energy, mineral and

Act, which allows the president to protect areas other resources found on public lands at low

of scientific or historical interest on federal lands prices to stimulate economic growth.

as national monuments. Roosevelt used this act President Herbert Hoover (a Republican)

to protect the Grand Canyon and other areas that went even further and proposed that the federal

would later become national parks. government return all remaining federal lands

Congress became upset with Roosevelt in to the states or sell them to private interests for

1907, because by then he had added vast tracts economic development. But the Great Depres-

to the forest reserves. Congress passed a law sion (1929–1941) made owning such lands

banning further executive withdrawals of public unattractive to state governments and private

forests. On the day before the bill became law, investors. The depression was bad news for the

Roosevelt defiantly reserved another large block country. But some say that without it we might

of land. Most environmental historians view have little if any of the public lands that make

Roosevelt (a Republican) as the country’s best up about one-third of the country’s land today

environmental president. (Figure 24-5, p. 641).

S32 SUPPLEMENT 5

1891–97 Timber 1920–27 Public
cutting banned on health boards
large tracts of public land. established
in most cities.

1870s 1880s 1890s 1900s 1910s 1920s

1880 1893 1918 Migratory Bird Act
Killer fog in London Few remaining restricts hunting of
kills 700 people. American bison migratory birds.
given refuge in
1872 Yellowstone 1916 National Park Service Act
Yellowstone National National Park. creates National Park
Park established. American System and National Park Service.
Forestry Association
organized by private 1892 Sierra Club 1915 Ecologists form
citizens to protect forests. founded by John Ecological Society of America.
American Public Health Muir to promote
Association formed. increased 1912 Public Health Service Act
preservation authorizes government
1870 of public land. investigation of water pollution.
First official Killer fog in
wildlife refuge London kills 1911 Weeks Act allows Forest Service
established 1,000 people. to purchase land at headwaters of
at Lake Merritt, navigable streams as part of
California. 1891 National Forest System.
Forest Reserve
Act authorized 1908 Swedish chemist Svante Arrhenius argues
the president to that increased emissions from burning fossil fuels will
set aside lead to global warming.
forest reserves.
1906 Antiquities Act allows president to set aside
1890 areas on federal lands as national monuments.
Government Pure Food and Drug Act enacted.
declares the
country's frontier 1905 U.S. Forest Service created. Audubon Society founded
closed. Yosemite by private citizens to preserve country's bird species.
National Park
established. 1904 Child lead poisoning linked to lead-based paints.

1903 First National Wildlife Refuge at Pelican Island,
Florida, established by President Theodore Roosevelt.

1902 Reclamation Act promotes irrigation
and water development projects in arid West.

1900 Lacey Act bans interstate shipment of
birds killed in violation of state laws.

1870–1930

Figure 2 Examples of the increased role of the federal government in resource conservation
and public health and the establishment of key private environmental groups, 1870–1930.
Question: Which two of these events do you think were the most important?

Figure 3 John Muir (1838–1914) was a geologist, ex-
plorer, and naturalist. He spent 6 years studying, writ-
ing journals, and making sketches in the wilderness of
California’s Yosemite Valley and then went on to ex-
plore wilderness areas in Utah, Nevada, the Northwest,
and Alaska. He was largely responsible for establishing
Yosemite National Park in 1890. He also founded the
Sierra Club and spent 22 years lobbying actively for con-
servation laws.

SUPPLEMENT 5 S33

Figure 4 Theodore (Teddy) Roosevelt arid western states, including Hoover Dam on the
(1858–1919) was a writer, explorer, natu- Colorado River (Figure 13-14, p. 327). The goals
ralist, avid birdwatcher, and twenty-sixth were to provide jobs, flood control, cheap irriga-
president of the United States. He was tion water, and cheap electricity for industry.
the first national political figure to bring
the issues of conservation to the atten- Congress enacted the Soil Conservation Act
tion of the American public. According to in 1935. It established the Soil Erosion Service
many historians, he has contributed more as part of the Department of Agriculture to
than any other president to natural re- correct the enormous erosion problems that
source conservation in the United States. had ruined many farms in the Great Plains
states during the depression, as discussed on
What Happened between Corps (CCC) in 1933. It put 2 million unem- pp. 303–305. Its name was later changed to the
1930 and 1960? ployed people to work planting trees and de- Soil Conservation Service, now called the Natural
veloping and maintaining parks and recreation Resources Conservation Service. Many environ-
A second wave of national resource conservation areas. The CCC also restored silted waterways mental historians praise Roosevelt (a Democrat)
and improvements in public health began in the and built levees and dams for flood control. for his efforts to get the country out of a major
early 1930s (Figure 5) as President Franklin D. economic depression and to help restore envi-
Roosevelt (1882–1945) strove to bring the coun- The government built and operated many ronmentally degraded areas.
try out of the Great Depression. He persuaded large dams in the Tennessee Valley and in the
Congress to enact federal government programs Federal resource conservation and pub-
to provide jobs and to help restore the country’s lic health policy during the 1940s and 1950s
degraded environment. changed little, mostly because of preoccupation
with World War II (1941–1945) and economic
During this period, the government pur- recovery after the war.
chased large tracts of land from cash-poor land-
owners, and established the Civilian Conservation Between 1930 and 1960, improvements in
public health included establishment of public
1930s 1940s health boards and agencies at the munici-
pal, state, and federal levels; increased public
education about health issues; introduction of
vaccination programs; and a sharp reduction in
the incidence of waterborne infectious diseases,
mostly because of improved sanitation and
garbage collection.

1950s

1938 Federal Food, Drug, 1949 Aldo 1957 Price-Anderson Act greatly
and Cosmetic Act regulates Leopold’s Sand limits liability of power plant
consumer foods, drugs, County Almanac owners and the government in
and cosmetics. published. cases of a major nuclear power
plant accident.
1937 Federal Aid in Wildlife 1948 Air pollution
Restoration Act levies federal disaster at Donora, 1956 Water Pollution Control Act
tax on gun and ammunition Pennsylvania, kills provides grants to states for water
sales, with funds used for 20 and sickens treatment plants. 1,000 people
wildlife research and protection. 7,000 people. killed in London smog incident.
Term greenhouse effect coined
by Professor Glen Trewaha. 1947 Federal Insecticide, 1954 Atomic Energy Act promotes
Fungicide, and Rodent- development of nuclear power plants.
1935 Soil Conservation Act creates icide Act regulates use
Soil Erosion Service. Wilderness of pesticides. Everglades 1952 4,000 people die in London killer smog.
Society founded. National Park established.
Defenders of Wildlife 1950 The Nature Conservancy formed.
1934 Taylor Grazing Act regulates founded.
livestock grazing on public lands.
Migratory Bird Hunting Stamp Act 1941 Rooftop solar water
requires federal license for duck heaters widely used
hunters, with funds used for waterfowl in Florida.
refuges. Dust bowl storms begin in Midwest.
1940 U.S. Fish and
1933 Civilian Conservation Corps established. Wildlife Service created
to manage National
Wildlife Refuge
system and protect
endangered species.

1930–1960

Figure 5 Some important conservation and environmental events, 1930–1960. Question: Which two of these
events do you think were the most important?

S34 SUPPLEMENT 5

1965–69
Severe pollution of Lake Erie
kills fish and closes beaches.

1960s

1961 World 1963 300 deaths 1964 Wilderness 1967 Environmental 1969 Oil-polluted Cuyahoga
Wildlife Fund and thousands of Act establishes Defense Fund River, flowing through
founded. illnesses in New York National formed. Cleveland, Ohio, catches
City from air pollution. Wilderness fire. Leaks from offshore oil
Clean Air Act begins System. 1968 Biologist Paul Ehrlich well off coast of Santa
regulation of air publishes The Population Barbara, California, kill
pollution with stricter Bomb. Biologist Garrett wildlife and pollute beaches.
amendments in 1965, Hardin publishes Tragedy Environmental Policy Act
1970, and 1990. of the Commons article. requires federal agencies
UN Biosphere Conference to to evaluate environmental
1962 Rachel Carson publishes Silent 1965 Land and Water discuss global environmental impact of their actions.
Spring to alert the public about Conservation Act authorizes problems. Apollo mission photo of
harmful effects of pesticides. 750 federal funds for local, state, the earth from space leads
people die in London smog incident. and federal purchase of open to spaceship-earth
space and parkland. environmental worldview.

1960s

Figure 6 Some important environmental events during the 1960s. Question: Which two of these events do you
think were the most important?

What Happened during the 1960s? The public also became aware that pollution and In 1978, the Federal Land Policy and Manage-
loss of habitat were endangering well-known ment Act gave the Bureau of Land Management
A number of milestones in American envi- wildlife species such as the North American (BLM) its first real authority to manage the
ronmental history occurred during the 1960s bald eagle, grizzly bear, whooping crane, and public land under its control, 85% of which is
(Figure 6). In 1962, biologist Rachel Carson peregrine falcon. in 12 western states. This law angered a number
(1907–1964) published Silent Spring, which of western interests whose use of these public
documented the pollution of air, water, and During the 1968 U.S. Apollo 8 mission to the lands was restricted for the first time.
wildlife from use of pesticides such as DDT (see moon, astronauts photographed the earth for the
Individuals Matter, p. 295). This influential book first time from lunar orbit. This allowed people In response, a coalition of ranchers, miners,
helped to broaden the concept of resource con- to see the earth as a tiny blue and white planet loggers, developers, farmers, some elected of-
servation to include preservation of the quality in the black void of space (Figure 1-1, p. 5), and ficials, and others launched a political campaign
of the air, water, soil, and wildlife. it led to the development of the spaceship-earth known as the sagebrush rebellion. It had two
environmental worldview. It reminded us that we major goals. First, sharply reduce government
Many environmental historians mark live on a planetary spaceship that we should not regulation of the use of public lands. Second,
Carson’s wake-up call as the beginning of the harm because it is the only home we have. remove most public lands in the western United
modern environmental movement in the States from federal ownership and management
United States. It flourished when a growing What Happened during the 1970s? and turn them over to the states. Then the plan
number of citizens organized to demand that The Environmental Decade was to persuade state legislatures to sell or lease
political leaders enact laws and develop policies the resource-rich lands at low prices to ranching,
to curtail pollution, clean up polluted environ- During the 1970s, media attention, public con- mining, timber, land development, and other
ments, and protect unspoiled areas from envi- cern about environmental problems, scientific private interests. This represented a return to
ronmental degradation. research, and action to address environmental President Hoover’s plan to get rid of all public
concerns grew rapidly. This period is sometimes land, which had been thwarted by the Great
In 1964, Congress passed the Wilderness Act, called the environmental decade, or the first decade Depression.
inspired by the vision of John Muir more than of the environment (Figure 7).
80 years earlier. It authorized the government Jimmy Carter (a Democrat), president be-
to protect undeveloped tracts of public land as The first annual Earth Day was held on tween 1977 and 1981, was very responsive to
part of the National Wilderness System, unless April 20, 1970. During this event, proposed by environmental concerns. He persuaded Congress
Congress later decides they are needed for the Senator Gaylord Nelson (1916–2005), some 20 to create the Department of Energy in order to
national good. Land in this system is to be used million people in more than 2,000 communi- develop a long-range energy strategy to reduce
only for nondestructive forms of recreation such ties took to the streets to heighten awareness the country’s heavy dependence on imported
as hiking and camping. and to demand improvements in environmental oil. He appointed respected environmental
quality. leaders to key positions in environmental and
Between 1965 and 1970, the emerging resource agencies and consulted with environ-
science of ecology received widespread media Republican President Richard Nixon mental interests on environmental and resource
attention. At the same time, the popular writ- (1913–1994) responded to the rapidly growing policy matters.
ings of biologists such as Paul Ehrlich, Barry environmental movement. He established the
Commoner, and Garrett Hardin awakened Environmental Protection Agency (EPA) in 1970 In 1980, Carter helped to create a Superfund
people to the interlocking relationships among and supported passage of the Endangered Species as part of the Comprehensive Environment Response,
population growth, resource use, and pollution. Act of 1973. This greatly strengthened the role of Compensation, and Liability Act (pp. 582–583) to
the federal government in protecting endan- clean up abandoned hazardous waste sites, in-
During that period, a number of events in- gered species and their habitats. cluding the Love Canal housing development in
creased public awareness of pollution (Figure 6).

SUPPLEMENT 5 S35

1970s

1973 1975 1978
OPEC cuts off oil to the U.S. Energy Policy and
and other nations supporting Conservation Act Love Canal, New York,
Israel. Lead-Based Paint Poisoning promotes energy
1971 Act regulates use of lead in conservation. housing development
Biologist Barry toys and cooking and
Commoner publishes eating utensils. Convention on evacuated because of
The Closing Circle International Trade in
explaining ecological Endangered Species (CITES) toxic wastes leaking from
problems and calling becomes international law.
for pollution prevention. old dumpsite. Federal

Land Policy and

Management Act

strengthens regulation of

public lands by the Bureau

of Land Management.

1974 1977
Chemists Sherwood Roland and Mario
Molina suggest CFCs are depleting the Clean Water Act strengthens
ozone in stratosphere. Lester Brown
founds the Worldwatch Institute. Safe regulation of drinking water
Drinking Water Act sets standards for
contaminants in public water supply. quality, with additional

amendments in 1981 and 1987.

Surface Mining Control and

Reclamation Act regulates

surface mining and

1972 encourages reclamation of
Oregon passes first beverage bottle recycling law. Publication of Limits to Growth,
which challenges idea of unlimited economic growth. David Brower founds Earth mined land. Amory B. Lovins 1979
Island Institute. Federal Environmental Pesticide Control Act regulates registration
of pesticides based on tests and degree of risk. Ocean Dumping Act; Marine publishes Soft Energy Paths Accident at
Protection, Research, and Sanctuaries Act; and Coastal Zone Management Act calling for switching from fossil Three Mile Island
help regulate and protect oceans and coastal areas. Marine Mammal Protection Act
encourages protection and conservation of marine mammals. Consumer Product fuels and nuclear power to nuclear power
Safety Act helps protect consumers from hazardous products. UN conference on the solar energy. U.S. Department plant in
Human Environment in Stockholm, Sweden.
of Energy created. Pennsylvania.

Oil shortage

because of

revolution in Iran.

1970 1976
First Earth Day. EPA established by President Richard Nixon. National Forest Management Act establishes guidelines for managing
Occupational Health and Safety Act promotes safe working conditions. national forests.Toxic Substances Control Act regulates many toxic
Resource Conservation and Recovery Act regulates waste disposal and substances not regulated under other laws. Resource Conservation
encourages recycling and waste reduction. National Environmental Policy and Recovery Act requires tracking of hazardous waste and encourages
Act passed. Clean Air Act passed. Natural Resources Defense Council created. recycling, resource recovery, and waste reduction. Noise Control Act
regulates harmful noise levels. UN Conference on Human Settlements.

1970s

Figure 7 Some important environmental events during the 1970s, sometimes called the environmental
decade. Question: Which two of these events do you think were the most important?

Niagara Falls, New York, which was abandoned defeat environmental laws and regulations— opposition in Congress, public outrage, and legal
when hazardous wastes began leaking into efforts that persist today. challenges by environmental and conservation
yards, school grounds, and basements. organizations, whose memberships soared dur-
In 1981, Ronald Reagan (a Republican, ing this period.
Carter also used the Antiquities Act of 1906 1911–2004), a self-declared sagebrush rebel and
to triple the amount of land in the National advocate of less federal control, became presi- In 1988, an industry-backed, coalition called
Wilderness System and double the area in the dent. During his 8 years in office, he angered the wise-use movement was formed. Its major
National Park System (primarily by adding vast environmentalists by appointing to key federal goals were to weaken or repeal most of the
tracts in Alaska). He used the Antiquities Act to positions people who opposed most existing country’s environmental laws and regulations
protect more public land, in all 50 states, than environmental and public land-use laws and and destroy the effectiveness of the environ-
any president before him had done. policies. mental movement in the United States. Politi-
cally powerful coal, oil, mining, automobile,
What Happened during Reagan greatly increased private energy timber, and ranching interests helped back this
the 1980s? Environmental and mineral development and timber cutting movement.
Backlash on public lands. He also drastically cut federal
funding for research on energy conservation Upon his election in 1989, George H. W.
Figure 8 summarizes some key environmental and renewable energy resources and eliminated Bush (a Republican) promised to be “the envi-
events during the 1980s that shaped U.S. envi- tax incentives for residential solar energy and ronmental president.” But he received criti-
ronmental policy. During this decade, farmers energy conservation enacted during the Carter cism from environmentalists for not providing
and ranchers and leaders of the oil, coal, auto- administration. In addition, he lowered automo- leadership on such key environmental issues as
mobile, mining, and timber industries strongly bile gas mileage standards and relaxed federal air population growth, global warming, and loss of
opposed many of the environmental laws and and water quality pollution standards. biodiversity. He also continued support of ex-
regulations developed in the 1960s and 1970s. ploitation of valuable resources on public lands
They organized and funded multiple efforts to Although Reagan was immensely popular, at giveaway prices. In addition, he allowed some
many people strongly opposed his environmen- environmental laws to be undercut by the politi-
tal and resource policies. This resulted in strong

S36 SUPPLEMENT 5

1980–89
Rise of a strong anti-environmental movement.

1980s

1985 Scientists discover annual 1986 Explosion of 1987 Montreal Protocol 1989 Exxon Valdez
seasonal thinning of the ozone Chernobyl nuclear to halve emissions of oil tanker
layer above Antarctica. power plant in Ukraine. ozone-depleting accident in
Times Beach, Missouri, CFCs signed by Alaska's Prince
1984 Toxic fumes leaking from pesticide plant evacuated and bought 24 countries. William Sound.
in Bhopal, India, kill at least 6,000 people and by EPA because of International Basel
injure 50,000–60,000. Lester R. Brown dioxin contamination. Convention controls 1988 Industry-backed
publishes first annual State of the World report. movement of wise-use movement
hazardous wastes established to weaken
1983 U.S. EPA and National Academy of Sciences publish from one country and destroy U.S.
reports finding that buildup of carbon dioxide and other to another. environmental movement.
greenhouse gases will lead to global warming. Biologist E. O. Wilson
publishes Biodiversity,
1980 Superfund law passed to clean up abandoned toxic waste detailing how human
dumps. Alaska National Interest Lands Conservation Act protects activities are affecting
42 million hectares (104 million acres) of land in Alaska. the earth's diversity
of species.

1980s

Figure 8 Some important environmental events during the 1980s. Question: Which two of these events do you
think were the most important?

cal influence of industry, mining, ranching, and environmental interests about environmental biodiversity protection, and threats from global
real estate development interests. They argued policy, as Carter had done. warming, increased.
that environmental laws had gone too far and
were hindering economic growth. He also vetoed most of the anti-environmen- In 2001, George W. Bush (a Republican)
tal bills (or other bills passed with anti-environ- became president. Like Reagan in the 1980s, he
What Happened from 1990 mental riders attached) passed by a Republican- appointed to key federal positions people who
to 2008? dominated Congress between 1995 and 2000. opposed or wanted to weaken many existing
He announced regulations requiring sport utility environmental and public land-use laws and
Between 1990 and 2008, opposition to environ- vehicles (SUVs) to meet the same air pollution policies because they were alleged to threaten
mental laws and regulations gained strength. emission standards as cars. Clinton also used ex- economic growth. Also like Reagan, he did not
This occurred because of continuing political and ecutive orders to make forest health the primary consult with environmental groups and leaders
economic support from corporate backers, who priority in managing national forests and to in developing environmental policies, and he
argued that environmental laws were hindering declare many roadless areas in national forests greatly increased private energy and mineral
economic growth, and because federal elections off limits to the building of roads and to logging. development and timber cutting on public lands.
gave Republicans (many of whom were gener-
ally unsympathetic to environmental concerns) In addition, he used the Antiquities Act of Bush also opposed increasing automobile gas
a majority in Congress. 1906 to protect various parcels of public land mileage standards as a way to save energy and
in the West from development and resource reduce dependence on oil imports, and he sup-
Consequently, during this period, leaders exploitation by declaring them national ported relaxation of various federal air and water
and supporters of the environmental movement monuments. He protected more public land as quality standards. Like Reagan, he developed an
have had to spend much of their time and funds national monuments in the lower 48 states than energy policy that emphasized use of fossil fuels
fighting efforts to discredit the movement and any other president, including Teddy Roosevelt and nuclear power with much less support dur-
weaken or eliminate most environmental laws and Jimmy Carter. However, environmental ing his first term for reducing energy waste and
passed during the 1960s and 1970s. They also leaders criticized Clinton for failing to push hard relying more on renewable energy resources.
have had to counter claims by anti-environmen- enough on key environmental issues such as
tal groups that problems such as global warming global warming energy policy and global and In addition, he withdrew the United States
and ozone depletion are hoaxes or are not very national biodiversity protection. from participation in the international Kyoto
serious and that environmental laws and regula- treaty, designed to help reduce carbon dioxide
tions have hindered economic growth. During the 1990s, many small and mostly emissions that can promote global warming
local grassroots environmental organizations and lead to long-lasting climate change. He
In 1993, Bill Clinton (a Democrat) became sprang up to deal with environmental threats in also repealed or tried to weaken most of the
president and promised to provide national and their local communities. Interest in environmen- pro-environmental measures established by
global environmental leadership. During his 8 tal issues increased on many college campuses Bill Clinton. On the other hand, in 2006, he cre-
years in office, he appointed respected environ- and environmental studies programs at colleges ated the world’s second largest marine reserve in
mental leaders to key positions in environmen- and universities expanded. In addition, aware- waters around some of the Hawaiian Islands.
tal and resource agencies and consulted with ness of important, complex environmental
issues, such as sustainability, population growth, According to leaders of a dozen major en-
vironmental organizations Bush, backed by a

SUPPLEMENT 5 S37

1991–2008 1995–2001 2001–2008
Continuing efforts by anti- Most efforts by Republican- President George W. Bush, backed by a Republican-
environmental movement dominated Congress to weaken dominated Congress between 2001 and 2006,
to repeal or weaken environ- or do away with environ- weakens many environmental laws, withdraws the U.S.
mental laws and discredit mental laws are vetoed by from participation in a global climate change treaty,
environmental movement. President Bill Clinton. greatly increases private energy and mineral
development and timber cutting on public lands, and
weakens wilderness protection and air pollution laws
governing older coal-burning power plants.
In 2006, President Bush created the world's second
largest protected marine area.

1990s 2000s

1992 Almost 1,700 of the 1995 Paul Cruzen, 2000 President Bill 2001 UN International
world’s senior scientists Mario Molina, and Clinton protects large Panel on Climate
release a warning about the Sherwood Rowland areas in national forests Change (IPCC) cites
seriousness of the world’s win Nobel Prize from roads and logging “new and stronger
environmental problems. for their work on and protects various evidence that most of
UN environmental summit ozone depletion by parcels of public the observed warming
at Rio de Janeiro, Brazil. chlorofluorocarbons land as national during the past 50 years
International Convention (CFCs). monuments. is attributable to human
on Biological Diversity. International Treaty activities.”
on Persistent Organic
1991 Persian Gulf War to 1994 UN Conference Pollutants (POPS) 2007 IPCC issues new report
protect oil supplies in on Population and requires phaseout concluding it is very likely
Middle East. Moratorium Development held in of twelve harmful (a 90-99% probability) that
on mining in Antarctica Cairo, Egypt. California chemicals. human activities, led by
for 50 years. National Desert Protection Act emissions of carbon dioxide
People of Color summit adds to the National 1997 Meeting of 161 from burning fossil fuels, have
to promote environ- Park System and nations in Kyoto, Japan, been the main cause of the
mental justice. wilderness system. to negotiate a treaty to observed atmospheric warming
help slow global warming. during the past 50 years.
1990 Twenty-first annual Earth Day 1993 Paul Hawken publishes Evaluation shows little
observed by 200 million people in The Ecology of Commerce progress in meeting goals of 2008 Little progress made in dealing
141 nations. Clean Air Act amended discussing relationships between 1992 Earth Summit meeting. with major environmental problems
to increase regulation of air pollutants ecology and business. such as biodiversity degradation,
such as sulfur dioxide and nitrogen oxides 1996 Theo Coburn energy policy, and projected climate
and to allow trading of air pollution credits. publishes Our Stolen change from global warming.
National Environmental Education Act Future warning of
authorizes funding of environmental dangers from hormone-
education programs at elementary disrupting chemicals.
and secondary school level.

Figure 9 Some important environmental events, 1990–2008 Question: Which two of these events do you think
were the most important?

Republican-dominated Congress during his first tion. These Democrats and Republicans urge than 2,500 of the world’s climate experts, issued
term, compiled the worst environmental record elected officials, regardless of party, to enter into its third report on global climate change. Ac-
of any president in the history of the country a new pact in which the United States becomes cording to this overwhelming consensus among
during his two terms in office. the world leader in making this the environ- the world’s climate scientists, global warming is
mental century. This would help to sustain the occurring and it is very likely (a 90–99% prob-
A few moderate Republican members of country’s rich heritage of natural capital and ability) that human activities, led by the burning
Congress have urged their party to return to provide economic development, jobs, and profits of fossil fuels, have been the main cause of the
its environmental roots, which were put down in rapidly growing businesses such as solar observed atmospheric warming during the past
during Teddy Roosevelt’s presidency, and to and wind energy, energy-efficient vehicles and 50 years. By 2008, the U.S. government had
shed its anti-environmental approach to legisla- buildings, ecological restoration, and pollution made little progress in facing up to the threat of
tion. Most Democrats agree and assert that the prevention. climate change from global warming.
environmental problems we face are much too
serious to be held hostage by political squab- In 2007, the Intergovernmental Panel on
bling. They call for cooperation, not confronta- Climate Change (IPCC), which includes more

S38 SUPPLEMENT 5

Some Basic Chemistry SUPPLEMENT
(Chapters 1–5)
6

Chemists Use the Periodic atomic number 11) with 11 positively charged is placed by itself above the center of the table
Table to Classify Elements protons and 11 negatively charged electrons because it does not fit very well into any of the
on the Basis of Their can lose one of its electrons. It then becomes groups
Chemical Properties a sodium ion with a positive charge of 1 (Naϩ)
because it now has 11 positive charges (protons) The elements arranged in a diagonal staircase
Chemists have developed a way to classify the but only 10 negative charges (electrons). pattern between the metals and nonmetals have
elements according to their chemical behavior, a mixture of metallic and nonmetallic properties
in what is called the periodic table of elements Nonmetals, found in the upper right of the and are called metalloids.
(Figure 1). Each horizontal row in the table is table, do not conduct electricity very well. Ex-
called a period. Each vertical column lists ele- amples are hydrogen (H), carbon (C), nitrogen Figure 1 also identifies the elements required
ments with similar chemical properties and is (N), oxygen (O), phosphorus (P), sulfur (S), as nutrients (black squares) for all or some forms
called a group. chlorine (Cl), and fluorine (F). of life and elements that are moderately or
highly toxic (red squares) to all or most forms
The partial periodic table in Figure 1 shows Atoms of some nonmetals such as chlo- of life. Six nonmetallic elements—carbon (C),
how the elements can be classified as metals, rine, oxygen, and sulfur tend to gain one or oxygen (O), hydrogen (H), nitrogen (N), sulfur
nonmetals, and metalloids. Most of the elements more electrons lost by metallic atoms to form (S), and phosphorus (P)—make up about 99%
found to the left and at the bottom of the table negatively charged ions such as O2Ϫ, S2Ϫ, and of the atoms of all living things.
are metals, which usually conduct electricity and ClϪ. For example, an atom of the nonmetallic
heat, and are shiny. Examples are sodium (Na), element chlorine (Cl, with atomic number 17) THINKING ABOUT
calcium (Ca), aluminum (Al), iron (Fe), lead can gain an electron and become a chlorine ion. The Periodic Table
(Pb), silver (Ag), and mercury (Hg). The ion has a negative charge of 1 (ClϪ) because
it has 17 positively charged protons and 18 Use the periodic table to identify by name and
Atoms of metals tend to lose one or more of negatively charged electrons. Atoms of nonmet- symbol two elements that should have chemical
their electrons to form positively charged ions als can also combine with one another to form properties similar to those of (a) Ca, (b) potas-
such as Naϩ, Ca2ϩ, and Al3ϩ. For example, an molecules in which they share one or more sium, (c) S, (d) lead.
atom of the metallic element sodium (Na, with pairs of their electrons. Hydrogen, a nonmetal,

1 VIIIA
2
H
Group Metals IIIA IVA VA VIA VIIA He
IA IIA hydrogen 5 6 7 8 9
Nonmetals helium
34 Atomic number 1 Required for
Metalloids all or some 10
H life-forms
Li Be Symbol VIB VIIB B C NO F Ne
24 25 26 hydrogen Moderately
lithium beryllium Name to highly boron carbon nitrogen oxygen fluorine neon
Cr Mn Fe 80 toxic
11 12 13 14 15 16 17 18
Hg IB IIB
Na Mg Al Si P S Cl Ar
mercury 29 30
sodium magnesium IIIB
20 21 IVB VB VIIIB 28 Cu Zn aluminum silicon phosphorus sulfur chlorine argon
19 22 23 27
Ni 31 32 33 34 35 36
Co
K Ca Sc Ti V Ga Ge As Se Br Kr

potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon

55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

cesium barium lanthanum hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon

Figure 1 Abbreviated periodic table of elements. Elements in the same vertical column, called a group, have similar
chemical properties. To simplify matters at this introductory level, only 72 of the 118 known elements are shown.

SUPPLEMENT 6 S39

Figure 2 A solid Sodium ion Water molecules Sodium chloride
crystal of an ionic com- in solution (NaCl) salt
pound such as sodium
chloride consists of Na+
a three–dimensional
array of oppositely Cl– Cl– Na+ Cl–
charged ions held to- Na+ Na+
gether by ionic bonds
resulting from the Cl– Cl–
strong forces of attrac- Cl– Na+
tion between opposite Na+ Cl– Na+
electrical charges. They
are formed when an Cl–
electron is transferred
from a metallic atom
such as sodium (Na) to
a nonmetallic element
such as chlorine (Cl).

Cl–

Chloride ion
in solution

Figure 3 How a salt
dissolves in water.

Ionic and Covalent Bonds Hold ure 2). The strong forces of attraction between Sodium chloride and many other ionic com-
Compounds Together such oppositely charged ions are called ionic pounds tend to dissolve in water and break apart
bonds. Because ionic compounds consist of ions into their individual ions (Figure 3).
Sodium chloride (NaCl) consists of a three- formed from atoms of metallic (positive ions)
dimensional network of oppositely charged and nonmetallic (negative ions) elements (Fig- NaCl Naϩ ϩ ClϪ
ions (Naϩ and ClϪ) held together by the forces ure 1), they can be described as metal–nonmetal
of attraction between opposite charges (Fig- compounds. sodium chloride sodium ion ϩ chloride ion
(in water)

HH OO NN Cl Cl Water, a covalent compound, consists of mol-
H2 O2 N2 CI2 ecules made up of uncharged atoms of hydrogen
(H) and oxygen (O). Each water molecule con-
hydrogen oxygen nitrogen chlorine sists of two hydrogen atoms chemically bonded
to an oxygen atom, yielding H2O molecules.
NO CO H Cl O The bonds between the atoms in such molecules
HH are called covalent bonds and form when the
NO CO HCI atoms in the molecule share one or more pairs
nitric oxide carbon monoxide hydrogen chloride H2O of their electrons. Because they are formed from
water atoms of nonmetallic elements (Figure 1), cova-
lent compounds can be described as nonmetal–
nonmetal compounds. Figure 4 shows the chemical
formulas and shapes of the molecules that are
the building blocks for several common covalent
compounds.

N OC O S O What Makes Solutions Acidic?
OO CO2 OO OO Hydrogen Ions and pH

NO2 carbon dioxide SO2 O3 The concentration, or number of hydrogen ions
nitrogen dioxide sulfur dioxide ozone (Hϩ) in a specified volume of a solution (typi-
cally a liter), is a measure of its acidity. Pure
H N O S water (not tap water or rainwater) has an equal
HH number of hydrogen (Hϩ) and hydroxide (OHϪ)
C H H S ions. It is called a neutral solution. An acidic
HH H OO solution has more hydrogen ions than hydrox-
ide ions per liter. A basic solution has more
H hydroxide ions than hydrogen ions per liter.

CH4 NH3 SO3 H2S Scientists use pH as a measure of the acid-
methane ammonia sulfur trioxide hydrogen sulfide ity of a solution based on its concentration of
hydrogen ions (Hϩ). By definition, a neutral
Figure 4 Chemical formulas and shapes for some covalent compounds formed when atoms of one or solution has a pH of 7, an acidic solution has a
more nonmetallic elements combine with one another and share one or more pairs of their electrons. pH of less than 7, and a basic solution has a pH
The bonds between the atoms in such molecules are called covalent bonds. greater than 7.

Each single unit change in pH represents a
10-fold increase or decrease in the concentra-
tion of hydrogen ions per liter. For example, an
acidic solution with a pH of 3 is 10 times more
acidic than a solution with a pH of 4. Figure 5

S40 SUPPLEMENT 6

0 Hydrochloric 100
acid (HCl) 10–1
1 Gastric fluid
(1.0–3.0) 10–2

2 Lemon juice,
some acid rain
10–3
3 Vinegar, wine, 10–4
beer, oranges

4 Tomatoes
Bananas

5 Black coffee 10–5
Bread
Typical rainwater
10–6
6 Urine (5.0–7.0) 10–7
Milk (6.6)

7 Pure water
Blood (7.3–7.5)
10–8
8 Egg white (8.0) 10–9
Seawater (7.8–8.3)
9 Baking soda
Phosphate detergents

Bleach, Tums 10–10

1 Soapy solutions,
0 Milk of magnesia

1 Household ammonia 10–11
1 (10.5–11.9) 10–12

12
Hair remover
shows the approximate pH and hydrogen 10–13
ion concentration per liter of solution for 13 Oven cleaner 10–14
various common substances. Figure 14 on 14 Sodium hydroxide (NaOH)
p. S9 of Supplement 2 shows how the pH of

precipitation varies in the lower U,S. states as a

result of acidic air pollutants discussed in detail

on pp. 479–480. Figure 5 The pH scale, representing the concentration of hydrogen ions (Hϩ) in one liter

of solution is shown on the righthand side. On the left side are the approximate pH values

THINKING ABOUT for solutions of some common substances. A solution with a pH less than 7 is acidic, one
pH with a pH of 7 is neutral, and one with a pH greater than 7 is basic. A change of 1 on the
pH scale means a tenfold increase or decrease in Hϩ concentration. (Modified from Cecie
A solution has a pH of 2. How many times more Starr, Biology: Today and Tomorrow, Pacific Grove, Calif.: Brooks/Cole, © 2005)
acidic is this solution than one with a pH of 6?

There Are Weak Forces Slightly δ−
of Attraction between negative O
Some Molecules charge

Ionic and covalent bonds form between the ions δ− H H H δ+
or atoms within a compound. There are also O δ+ δ+
weaker forces of attraction between the mol- δ−
ecules of covalent compounds (such as water) δ+ H δ− O δ+
resulting from an unequal sharing of electrons H
by two atoms.
δ− O H
For example, an oxygen atom has a much H
greater attraction for electrons than does a
hydrogen atom. Thus, in a water molecule the O H δ+ δ+ Figure 6 Hydrogen bond: slightly
electrons shared between the oxygen atom and H δ+ δ− unequal sharing of electrons in the
its two hydrogen atoms are pulled closer to the water molecule creates a molecule
oxygen atom, but not actually transferred to the δ+ H δ+ Hydrogen with a slightly negatively charged
oxygen atom. As a result, the oxygen atom in bonds
a water molecule has a slightly negative partial
charge and its two hydrogen atoms have a δ− H O end and a slightly positively charged
slightly positive partial charge (Figure 6). O δ+ end. Because of this electrical po-
H H larity, the hydrogen atoms of one
The slightly positive hydrogen atoms in one δ+ water molecule are attracted to
water molecule are then attracted to the slightly H the oxygen atoms in other water
negative oxygen atoms in another water mol- molecules. These fairly weak forces
ecule. These forces of attraction between water
molecules are called hydrogen bonds (Figure 6). Slightly of attraction between molecules

positive (represented by the dashed lines) are

charge called hydrogen bonds.

SUPPLEMENT 6 S41

They account for many of water’s unique prop- molecules—complex carbohydrates, proteins, play different roles. Some help to store energy.
erties (Science Focus, p. 67). Hydrogen bonds nucleic acids, and lipids—are molecular building Some are components of the immune system that
also form between other covalent molecules or blocks of life. protects the body against diseases and harm-
portions of such molecules containing hydrogen ful substances by forming antibodies that make
and nonmetallic atoms with a strong ability to Complex carbohydrates consist of two invading agents harmless. Others are hormones
attract electrons. or more monomers of simple sugars (such as that are used as chemical messengers in the
glucose, Figure 7) linked together. One example bloodstreams of animals to turn various bodily
Four Types of Large Organic is the starches that plants use to store energy functions on or off. In animals, proteins are also
Compounds Are the Molecular and also to provide energy for animals that feed components of hair, skin, muscle, and tendons.
Building Blocks of Life on plants. Another is cellulose, the earth’s most In addition, some proteins act as enzymes that
abundant organic compound, which is found in catalyze or speed up certain chemical reactions.
Larger and more complex organic compounds, the cell walls of bark, leaves, stems, and roots.
called polymers, consist of a number of basic Nucleic acids are large polymer molecules
structural or molecular units (monomers) linked Proteins, are large polymer molecules made by linking hundreds to thousands of four
by chemical bonds, somewhat like rail cars formed by linking together long chains of types of monomers called nucleotides. Two nucleic
linked in a freight train. Four types of macro- monomers called amino acids (Figure 8). Living acids—DNA (deoxyribonucleic acid) and RNA
organisms use about 20 different amino acid (ribonucleic acid)—participate in the building
molecules to build a variety of proteins, which of proteins and carry hereditary information
used to pass traits from parent to offspring. Each
General structure Chain of glucose units Starch nucleotide consists of a phosphate group, a sugar
HO molecule containing five carbon atoms (deoxy-
C ribose in DNA molecules and ribose in RNA
H C OH molecules), and one of four different nucleotide
bases (represented by A, G, C, and T, the first let-
HO C H ter in each of their names, or A, G, C, and U in
H C OH RNA; see Figure 9). In the cells of living organ-
H C OH isms, these nucleotide units combine in different
CH2OH numbers and sequences to form nucleic acids such
as various types of RNA and DNA (Figure 10).
CH2OH
H OH Hydrogen bonds formed between parts of the
four nucleotides in DNA hold two DNA strands
H together like a spiral staircase, forming a double
OH H helix (Figure 10). DNA molecules can unwind
HO OH and replicate themselves.

H OH The total weight of the DNA needed to
reproduce all of the world’s people is only about
Glucose (C6H12O6) 50 milligrams—the weight of a small match. If
the DNA coiled in your body were unwound,
Figure 7 Straight-chain and ring structural formulas of glucose, a simple sugar that can be it would stretch about 960 million kilometers
used to build long chains of complex carbohydrates such as starch and cellulose. (600 million miles)—more than six times the
distance between the sun and the earth.
General structure Chain of amino acids Protein
of amino acid The different molecules of DNA that make
up the millions of species found on the earth are
Amino Carboxyl like a vast and diverse genetic library. Each spe-
group group cies is a unique book in that library. The genome
of a species is made up of the entire sequence
H H O– of DNA “letters” or base pairs that combine to
+H N “spell out” the chromosomes in typical members
CC of each species. In 2002, scientists were able to
H map out the genome for the human species by
RO
Deoxyribose in DNA
R side group Ribose in RNA
(20 kinds, each with
distinct properties) Phosphate 5-Carbon sugar Nucleotide base

Amino acid Figure 9 Generalized structures of the nucleotide
molecules linked in various numbers and sequences
HH O– to form large nucleic acid molecules such as various
+H N C CO types of DNA (deoxyribonucleic acid) and RNA (ri-
CH3 bonucleic acid). In DNA, the 5-carbon sugar in each
H HC nucleotide is deoxyribose; in RNA it is ribose. The
four basic nucleotides used to make various forms
CH3 of DNA molecules differ in the types of nucleotide
Valine bases they contain—guanine (G), cytosine (C), ad-
enine (A), and thymine (T). (Uracil, labeled U, occurs
Figure 8 General structural formula of amino acids and a specific structural formula of one of instead of thymine in RNA.)
the 20 different amino acid molecules that can be linked together in chains to form proteins
that fold up into more complex shapes.

S42 SUPPLEMENT 6

Nucleotide base 5-carbon sugar Figure 10 Portion of the double helix of a analyzing the 3.1 billion base sequences in hu-
(G, C, A, T) (deoxyribose) DNA molecule. The double helix is composed of man DNA.
two spiral (helical) strands of nucleotides. Each
Nucleotide OH nucleotide contains a unit of phosphate (P), de- Lipids, a fourth building block of life, are a
oxyribose (S), and one of four nucleotide bases: chemically diverse group of large organic com-
P A S guanine (G), cytosine (C), adenine (A), and thy- pounds that do not dissolve in water. Examples
T P mine (T). The two strands are held together by are fats and oils for storing energy (Figure 11),
Phospate hydrogen bonds formed between various pairs waxes for structure, and steroids for producing
S group of the nucleotide bases. Guanine (G) bonds with hormones.
cytosine (C), and adenine (A) with thymine (T).
Figure 12 shows the relative sizes of simple
and complex molecules, cells, and multicelled
organisms.

P C G
S
S Fatty acid Fat molecule
(lipid) (triglyceride)

P Hydrogen bond P HO O
S S C
AT
HCH

HCH

P P HCH Fatty tissue
GS HCH (adipose cells)
C HCH
S P HCH
AS HCH
DNA consists P HCH

of two strands of T
S

nucleotides linked

by hydrogen bonds

(shown as dotted

red lines)

HCH

H

DNA double helix Figure 11 Structural formula of fatty acid that is one form of lipid (left).
Fatty acids are converted into more complex fat molecules that are
stored in adipose cells (right).

1 centimeter (cm) = 1/100 meter, or 0.4 inch
1 millimeter (mm) = 1/1,000 meter
1 micrometer (μm) = 1/1,000,000 meter
1 nanometer (nm) = 1/1,000,000,000 meter

1 meter = 102 cm = 103 mm = 106 μm = 109 nm

Light microscopes Human eye, no microscope
Electron microscopes
Humans
Hummingbirds

Lipids Bacteriophages Most animal cells
and plant cells
Mitochondria,
chloroplasts

Small Proteins Most Frog
molecules bacteria eggs

0.1 nm 1 nm 10 nm 100 nm 1 μm 10 μm 100 μm 1 mm 1 cm 0.1 m 1m 10 m 100 m
Redwoods
Figure 12 Relative size of simple molecules, complex molecules, cells, and multicellular organisms. This scale is
exponential, not linear. Each unit of measure is 10 times larger than the unit preceding it. (Used by permission from
Cecie Starr and Ralph Taggart, Biology, 11th ed, Belmont, Calif.: Thomson Brooks/Cole, © 2006)

SUPPLEMENT 6 S43

Figure 13 ATP synthesis: P Energy ATP breakdown:
Energy storage Energy is stored in ATP Energy stored in ATP is released
and release in
cells. A P P+ A PPP
ATP
ADP Phosphate

A PPP A P P+ P Energy
ATP
ADP Phosphate

Certain Molecules Store and as glucose (C6H12O6, Figure 7, p. S42) that plant
Release Energy in Cells cells can use as a source of energy and carbon.

Sun Chemical reactions occurring in photosynthesis Chemists Balance Chemical
(pp. 58–59) release energy that is absorbed by Equations to Keep Track
Chlorophyll adenosine diphosphate (ADP) molecules and of Atoms
H2O Light-dependent stored as chemical energy in adenosine triphos-
phate (ATP) molecules (Figure 13, left). When Chemists use a shorthand system to
reaction cellular processes require energy, ATP molecules
Energy storage release it to form ADP molecules (Figure 13, represent chemical reactions. These chemi-
right).
and release cal equations are also used as an accounting
(ATP/ADP)
system to verify that no atoms are created or

A Closer Look at Photosynthesis destroyed in a chemical reaction as required
by the law of conservation of matter (p. 39
In photosynthesis, sunlight powers a complex
series of chemical reactions that combine water and Concept 2-3, p. 40). As a con-
taken up by plant roots and carbon dioxide sequence, each side of a chemical
from the air to produce sugars such as glucose.
This process converts solar energy into chemi- equation must have the same number of atoms
cal energy in sugars for use by plant cells, with or ions of each element involved. Ensuring that
the solar energy captured, stored, and released
as chemical energy in ATP and ADP molecules this condition is met leads to what chemists call
(Figure 13). Figure 14 is a greatly simplified
summary of the photosynthesis process. a balanced chemical equation. The equation for

Photosynthesis takes place within tiny en- the burning of carbon (C ϩ O2 CO2) is bal-
closed structures called chloroplasts found within
plant cells. Chlorophyll, a special compound anced because one atom of carbon and two at-
in chloroplasts, absorbs incoming visible light
mostly in the violet and red wavelengths. The oms of oxygen are on both sides of the equation.
green light that is not absorbed is reflected back,
which is why photosynthetic plants look green. Consider the following chemical reaction:
The absorbed wavelengths of solar energy initi-
ate a sequence of chemical reactions with other When electricity passes through water (H2O),
molecules in what are called light-dependent the latter can be broken down into hydrogen
reactions.
(H2) and oxygen (O2), as represented by the fol-
This series of reactions splits water into lowing equation:
hydrogen ions (Hϩ) and oxygen (O2) which
is released into the atmosphere. Small ADP H2O H2 ϩ O2
molecules in the cells absorb the energy released
Chloroplast and store it as chemical energy in ATP mol- 2 H atoms 2 H atoms 2 O atoms
in leaf cell ecules (Figure 13). The chemical energy released 1 O atom
by the ATP molecules drives a series of light-
O2 independent (dark) reactions in the plant cells. In This equation is unbalanced because one
this second sequence of reactions, carbon atoms atom of oxygen is on the left side of the equa-
stripped from carbon dioxide combine with tion but two atoms are on the right side.
hydrogen and oxygen to produce sugars such
We cannot change the subscripts of any of
the formulas to balance this equation because
that would change the arrangements of the
atoms, leading to different substances. Instead,
we must use different numbers of the molecules
involved to balance the equation. For example,
we could use two water molecules:

2 H2O H2 ϩ O2

4 H atoms 2 H atoms 2 O atoms
2 O atoms

CO2 Light-independent Glucose Figure 14 Simplified overview of photosynthesis. This equation is still unbalanced. Although
reaction C6H12O6 + 6O2 In this process, chlorophyll molecules in the chlo- the numbers of oxygen atoms on both sides of
roplasts of plant cells absorb solar energy. This the equation are now equal, the numbers of
initiates a complex series of chemical reactions in hydrogen atoms are not.
which carbon dioxide and water are converted to
sugars such as glucose and oxygen. We can correct this problem by having the
reaction produce two hydrogen molecules:

2 H2O 2 H2 ϩ O2

Sunlight 4 H atoms 4 H atoms 2 O atoms
2 O atoms
6CO2 + 6H2O

S44 SUPPLEMENT 6

Now the equation is balanced, and the law of Researchers hope to incorporate nanopar- be hazardous at the nanoscale when they are
conservation of matter has been observed. For ticles of hydroxyapatite, with the same chemical inhaled, ingested, or absorbed through the skin.
every two molecules of water through which we structure as tooth enamel, into toothpaste to
pass electricity, two hydrogen molecules and one put coatings on teeth that prevent bacteria from We know little about such effects and risks at
oxygen molecule are produced. penetrating. Nanotech coatings now being used a time when the use of untested and unregu-
on cotton fabrics form an impenetrable barrier lated nanoparticles is increasing exponentially.
THINKING ABOUT that causes liquids to bead and roll off. Such A few toxicological studies are sending up red
Chemical Equations stain-resistant fabrics used to make clothing, flags:
rugs, and furniture upholstery could eliminate • In 2004, Eva Olberdorster, an environmental
Try to balance the chemical equation for the the need to use harmful chemicals for removing
reaction of nitrogen gas (N2) with hydrogen gas stains. toxicologist at Southern Methodist Uni-
(H2) to form ammonia gas (NH3). versity, found that fish swimming in water
Self-cleaning window glass coated with a loaded with a certain type of carbon nano-
Scientists Are Learning How layer of nanoscale titanium dioxide (TiO2) par- molecule called buckyballs experienced brain
to Build Materials from the ticles is now available. As the particles interact damage within 48 hours.
Bottom Up: Nanotechnology with UV rays from the sun, dirt on the surface of • In 2005, NASA researchers found that inject-
the glass loosens and washes off when it rains. ing commercially available carbon nanotubes
Nanotechnology (Science Focus, p. 362) uses Similar products can be used for self-cleaning into rats caused significant lung damage.
atoms and molecules to build materials from the sinks and toilet bowls. • A 2005 study by researchers at the U.S. Na-
bottom up using atoms of the elements in the tional Institute of Occupational Safety and
periodic table as its raw materials. A nanometer Scientists are working on ways to replace Health found substantial damage to the heart
(nm) is one-billionth of a meter—equal to the the silicon in computer chips with carbon-based and aortic arteries of mice exposed to carbon
length of about 10 hydrogen atoms lined up side nanomaterials that greatly increase the process- nanotubes.
by side. A DNA molecule (Figure 10) is about ing power of computers. Biological engineers are • In 2005, researchers at New York’s University
2.5 nanometers wide. A human hair has a width working on nanoscale devices that could deliver of Rochester found increased blood clotting
of 50,000 to 100,000 nanometers. drugs. Such devices could penetrate cancer cells in rabbits inhaling carbon buckyballs.
and deliver nanomolecules that could kill the
For objects smaller than about 100 nano- cancer cells from the inside. Researchers also In 2004, the British Royal Society and Royal
meters, the properties of materials change dra- hope to develop nanoscale crystals that could Academy of Engineering recommended that we
matically. At this nanoscale level, materials can change color when they detect tiny amounts avoid the environmental release of nanoparticles
exhibit new properties, such as extraordinary (measured in parts per trillion) of harmful and nanotubes as much as possible until more
strength or increased chemical activity, that they substances such chemical and biological warfare is known about their potential harmful impacts.
do not exhibit at the much larger macroscale level agents and food pathogens. For example, a color They recommended as a precautionary measure
that we are all familiar with. change in food packaging could alert a consumer that factories and research laboratories treat
when a food is contaminated or has begun to manufactured nanoparticles and nanotubes as if
For example, scientists have learned how spoil. The list of possibilities could go on. they were hazardous to their workers and to the
to make tiny tubes of carbon atoms linked general public. GREEN CAREER: Nanotechnology
together in hexagons. Experiments have shown By 2008, more than 1,000 products contain-
that these carbon nanotubes are the strongest ing nanoscale particles were commercially avail- THINKING ABOUT
material ever made—60 times stronger than able and thousands more were in the pipeline. Nanotechnology
high-grade steel. Such nanotubes have been Examples are found in cosmetics, sunscreens,
linked together to form a rope so thin that it is fabrics, pesticides, and food additives. Do you think that the benefits of nanotechnol-
invisible, but strong enough to suspend a pickup ogy outweigh its potentially harmful effects?
truck. So far, these products are unregulated and Explain. What are three things you would do to
unlabeled. This concerns many health and reduce its potentially harmful effects?
At the macroscale, zinc oxide (ZnO) can be environmental scientists because the tiny size of
rubbed on the skin as a white paste to protect nanoparticles can allow them to penetrate the RESEARCH FRONTIER
against the sun’s harmful UV rays; at the nano- natural defenses of the body against invasions
scale it becomes transparent and is being used as by foreign and potentially harmful chemicals Learning more about nanotechnology and how
invisible coatings to protect the skin and fabrics and pathogens. Nanoparticles of a chemical to reduce its potentially harmful effects. See
from UV damage. Because silver (Ag) can kill tend to be much more chemically reactive than academic.cengage.com/biology/miller.
harmful bacteria, silver nanocrystals are being macroparticles of the chemical, largely because
incorporated into bandages for wounds. the tiny nanoparticles have relatively large sur-
face areas for their small mass. This means that a
chemical that is harmless at the macroscale may

SUPPLEMENT 6 S45

SUPPLEMENT

7 Classifying and Naming Species
(Chapters 3, 4, 8)

All organisms on the earth today are descen- thermal vents, and acidic soil. These organisms than 2 years, such as roses, grapes, elms, and
magnolias.
dants of single-cell organisms that lived almost 4 live in extreme environments.
Animals are also many-celled, eukaryotic
billion years ago. As a result of biological evolu- The remaining four kingdoms—protists, organisms. Most have no backbones and hence
are called invertebrates. Invertebrates include
tion through natural selection, life has evolved fungi, plants, and animals (Figure 4-3, p. 81) sponges, jellyfish, worms, arthropods (e.g.,
insects, shrimp, and spiders), mollusks (e.g.,
into six major groups of species, called kingdoms: are eukarotes with one or more cells that have snails, clams, and octopuses), and echinoderms
(e.g., sea urchins and sea stars). Vertebrates
eubacteria, archaebacteria, protists, fungi, plants, and a nucleus and complex internal compartments (animals with backbones and a brain protected
by skull bones) include fishes (e.g., sharks and
animals (Figure 4-3, p. 81). (Figure 3-2a, p. 52). Protists are mostly single- tuna), amphibians (e.g., frogs and salamanders),
reptiles (e.g., crocodiles and snakes), birds (e.g.,
Eubacteria are prokaryotes with single cells celled eukaryotic organisms, such as diatoms, eagles and robins), and mammals (e.g., bats,
elephants, whales, and humans).
that lack a nucleus and other internal compart- dinoflagellates, amoebas, golden brown and
Within each kingdom, biologists have created
ments (Figure 3-2b, p. 52) found in the cells of yellow-green algae, and protozoans. Some subcategories based on anatomical, physiologi-
cal, and behavioral characteristics. Kingdoms are
species from other kingdoms. Examples include protists cause human diseases such as malaria divided into phyla, which are divided into sub-
groups called classes. Classes are subdivided into
various cyanobacteria and bacteria such as (pp. 444–447) and sleeping sickness. orders, which are further divided into families.
Families consist of genera (singular, genus), and
staphylococcus and streptococcus. Fungi are mostly many-celled, sometimes each genus contains one or more species. Note
that the word species is both singular and plural.
Archaebacteria are single-celled bacteria that microscopic, eukaryotic organisms such as Figure 1 shows this detailed taxonomic classifi-
cation for the current human species.
are closer to eukaryotic cells (Figure 3-2a, p. 52) mushrooms, molds, mildews, and yeasts. Many
Most people call a species by its common
than to eubacteria. Examples include metha- fungi are decomposers (Figure 3-11, p. 60). name, such as robin or grizzly bear. Biologists
use scientific names (derived from Latin) con-
nogens, which live in oxygen-free sediments of Other fungi kill various plants and animals and sisting of two parts (printed in italics, or under-
lined) to describe a species. The first word is the
lakes and swamps and in animal guts; halo- cause huge losses of crops and valuable trees. capitalized name (or abbreviation) for the genus
to which the organism belongs. It is followed by
philes, which live in extremely salty water; and Plants are mostly many-celled eukaryotic a lowercase name that distinguishes the species
from other members of the same genus. For ex-
thermophiles, which live in hot springs, hydro- organisms such as red, brown, and green algae ample, the scientific name of the robin is Turdus
migratorius (Latin for “migratory thrush”) and
and mosses, ferns, and flowering plants the grizzly bear goes by the scientific name Ursus
horribilis (Latin for “horrible bear”).
(whose flowers produce seeds that
Figure 1 Taxonomic classification of the latest
perpetuate the species). Some human species, Homo sapiens sapiens.

Animalia Many-celled eukaryotic plants such as corn and mari-

organisms golds are annuals, meaning

Chordata Animals with notochord (a that they complete their
long rod of stiffened tissue), nerve life cycles in one growing
cord, and a pharynx (a muscular tube season. Others are
used in feeding, respiration, or both) perennials, which
can live for more

Kingdom Vertebrata Spinal cord enclosed in
a backbone of cartilage or bone; and
skull bones that protect the brain

Phylum Mammalia Animals whose young are
Subphylum nourished by milk produced by
Class mammary glands of females, and
Order that have hair or fur and warm blood

Primates Animals that live in trees
or are descended from
tree dwellers

Hominidae Upright animals with
two-legged locomotion and
binocular vision

Family Homo Upright animals with large brain,
Genus language, and extended parental
Species care of young
Species
sapiens Animals with sparse body hair,
high forehead, and large brain

sapiens sapiens Animals capable
of sophisticated cultural evolution

S46 SUPPLEMENT 7

Weather Basics: El Niño, Tornadoes, and SUPPLEMENT
Tropical Cyclones (Chapters 4, 7, 11)
8

Weather Is Affected by Moving A cold front (Figure 1, right) is the leading Figure 2 A jet stream is a
Masses of Warm and Cold Air edge of an advancing mass of cold air. Because rapidly flowing air current
cold air is denser than warm air, an advancing that moves west to east
Weather is the set of short-term atmospheric cold front stays close to the ground and wedges in a wavy pattern. This
conditions—typically those occurring over hours underneath less dense warmer air. An approach- figure shows a polar jet
or days—for a particular area. Examples of at- ing cold front produces rapidly moving, tower- stream and a subtropi-
mospheric conditions include temperature, pres- ing clouds called thunderheads. cal jet stream in winter.
sure, moisture content, precipitation, sunshine, In reality, jet streams are
cloud cover, and wind direction and speed. As a cold front passes through, we may ex- discontinuous and their
perience high surface winds and thunderstorms. positions vary from day to
Meteorologists use equipment mounted on After it leaves the area, we usually have cooler day. (Used by permission
weather balloons, aircraft, ships, and satellites, temperatures and a clear sky. from C. Donald Ahrens,
as well as radar and stationary sensors, to obtain Meteorology Today, 8th
data on weather variables. They then feed these Near the top of the troposphere, hurricane- ed. Belmont, Calif.: Brooks/
data into computer models to draw weather force winds circle the earth. These powerful Cole, 2006)
maps. Other computer models project the
weather for a period of several days by calculat- winds, called jet streams, follow rising and falling
ing the probabilities that air masses, winds, and paths that have a strong influence on weather
other factors will change in certain ways. patterns (Figure 2).

Much of the weather we experience results Weather Is Affected by Changes
from interactions between the leading edges of in Atmospheric Pressure
moving masses of warm or cold air. Weather
changes as one air mass replaces or meets Changes in atmospheric pressure also affect
another. The most dramatic changes in weather weather. Atmospheric pressure results from mol-
occur along a front, the boundary between ecules of gases (mostly nitrogen and oxygen)
two air masses with different temperatures and in the atmosphere zipping around at very high
densities. speeds and hitting and bouncing off everything
they encounter.
A warm front is the boundary between an
advancing warm air mass and the cooler one it
is replacing (Figure 1, left). Because warm air
is less dense (weighs less per unit of volume)
than cool air, an advancing warm front rises up
over a mass of cool air. As the warm front rises,
its moisture begins condensing into droplets,
forming layers of clouds at different altitudes.
Gradually the clouds thicken, descend to a lower
altitude, and often release their moisture as
rainfall. A moist warm front can bring days of
cloudy skies and drizzle.

Cool Anvil top
air mass Cold front surface Warm air mass

Warm air mass

eWarm front surfac

Cold air mass

Figure 1 Weather fronts: a warm front (left) arises when an advancing mass of warm air meets and rises up over a
mass of denser cool air. A cold front (right) forms when a moving mass of cold air wedges beneath a mass of less
dense warm air.

SUPPLEMENT 8 S47

Atmospheric pressure is greater near the Every Few Years Major Wind water up from deeper layers. Strong upwellings
earth’s surface because the molecules in the Shifts in the Pacific Ocean Affect are also found along the steep western coasts
atmosphere are squeezed together under the Global Weather Patterns of some continents when winds blowing along
weight of the air above them. An air mass with the coasts push surface water away from the
high pressure, called a high, contains cool, An upwelling, or upward movement of ocean land and draw water up from the ocean bottom
dense air that descends toward the earth’s sur- water, can mix the water, bringing cool and nu- (Figure 3).
face and becomes warmer. Fair weather follows trient-rich water from the bottom of the ocean
as long as this high-pressure air mass remains to the surface where it supports large popula- Every few years in the Pacific Ocean, normal
over the area. tions of phytoplankton, zooplankton, fish, and shore upwellings (Figure 4, left) are affected
fish-eating seabirds. by changes in weather patterns called the El
In contrast, a low-pressure air mass, called Niño–Southern Oscillation, or ENSO (Figure 4,
a low, produces cloudy and sometimes stormy Figure 7-2 (p. 142) shows the oceans’ major right). In an ENSO, often called simply El Niño,
weather. Because of its low pressure and low upwelling zones. Upwellings far from shore oc- prevailing tropical trade winds blowing east to
density, the center of a low rises, and its warm cur when surface currents move apart and draw west weaken or reverse direction. This allows
air expands and cools. When the temperature
drops below a certain level where condensation Movement of
takes place, called the dew point, moisture in the surface water
air condenses and forms clouds.
Wind
If the droplets in the clouds coalesce into
larger drops or snowflakes heavy enough to fall Diving birds
from the sky, then precipitation occurs. The con-
densation of water vapor into water drops usu-
ally requires that the air contain suspended tiny
particles of material such as dust, smoke, sea
salts, or volcanic ash. These so-called condensa-
tion nuclei provide surfaces on which the droplets
of water can form and coalesce.

Upwelling Fish
Zooplankton

Phytoplankton

Figure 3 A shore upwelling occurs when deep, cool, nutri- Nutrients
ent-rich waters are drawn up to replace surface water that
has been moved away from a steep coast by wind flowing
along the coast toward the equator.

Drought in Winds weaken,
Australia and causing updrafts
Southeast Asia and storms

Surface winds
blow westward

EQUATOR

AUSTRALIA Warm waters SOUTH AUSTRALIA Warm water flow SOUTH
pushed westward AMERICA stopped or reversed AMERICA

Warm water Thermocline Warm water Warm water deepens off
Cold water South America

Thermocline

Cold water

Normal Conditions El Niño Conditions

Figure 4 Normal trade winds blowing east to west cause shore upwellings of cold, nutrient-rich bottom water in
the tropical Pacific Ocean near the coast of Peru (left). A zone of gradual temperature change called the thermo-
cline separates the warm and cold water. Every few years a shift in trade winds known as the El Niño–Southern
Oscillation (ENSO) disrupts this pattern. Trade winds blowing from east to west weaken or reverse direction, which
depresses the coastal upwellings and warms the surface waters off South America (right). When an ENSO lasts
12 months or longer, it severely disrupts populations of plankton, fish, and seabirds in upwelling areas and can alter
weather conditions over much of the globe (Figure 5).

S48 SUPPLEMENT 8

El Niño

Drought November 10, 1997

Unusually high rainfall Warm water of El Niño

Unusually warm periods Cool Warm

Figure 5 Typical global weather effects of an El Niño– February 27, 1999
Southern Oscillation. During the 1996–1998 ENSO, huge
waves battered the coast in the U.S. state of California and Cool water of La Niña Figure 6 Locations
torrential rains caused widespread flooding and mudslides. of flowing masses of
In Peru, floods and mudslides killed hundreds of people, warm and cold water
left about 250,000 people homeless, and ruined harvests. in the Pacific Ocean
Drought in Brazil, Indonesia, and Australia led to mas- during an El Niño
sive wildfires in tinder-dry forests. India and parts of Africa (top) and a La Niña
also experienced severe drought. A catastrophic ice storm (bottom). (Data from
hit Canada and the northeastern United States, but the Jet Propulsion Lab,
southeastern United States had fewer hurricanes. (Data NASA)
from United Nations Food and Agriculture Organization)

Data and Map Analysis

1. How might an ENSO affect the weather where you live or
go to school?

2. Why do you think the area to the west of El Niño suffers
drought?

the warmer waters of the western Pacific to
move toward the coast of South America,
which suppresses the normal upwellings of
cold, nutrient-rich water (Figure 4, right). The
decrease in nutrients reduces primary productiv-
ity and causes a sharp decline in the populations
of some fish species.

A strong ENSO can alter the weather of
at least two-thirds of the globe (Figure 5)—
especially in lands along the Pacific and Indian
Oceans. Scientists do not know for sure the
causes of an ENSO, but they know how to de-
tect its formation and track its progress.

La Niña, the reverse of El Niño, cools some
coastal surface waters, and brings back upwell-
ings. Typically, La Niña means more Atlantic
Ocean hurricanes, colder winters in Canada and
the northeastern United States, and warmer and
drier winters in the southeastern and southwest-
ern United States. It also usually leads to wetter
winters in the Pacific Northwest, torrential rains
in Southeast Asia, lower wheat yields in Argen-
tina, and more wildfires in Florida. Figure 6 uses
satellite data to show changes in the locations
of masses of warm and cold water in the Pacific
Ocean during an El Niño (top) and a La Niña
(bottom).

SUPPLEMENT 8 S49

Tornadoes and Tropical Cyclones
Are Violent Weather Extremes

Sometimes we experience weather extremes. Highest risk
Two examples are violent storms called torna-

does (which form over land) and tropical cyclones 40

(which form over warm ocean waters and some- 35
times pass over coastal land).

Tornadoes or twisters are swirling funnel- 30
shaped clouds that form over land. They can 25
destroy houses, cause other serious dam-

age, and kill people in areas where they touch 20
down on the earth’s surface. The United States

is the world’s most tornado-prone country, fol- 15

lowed by Australia. 10
Tornadoes in the plains of the midwestern

United States usually occur when a large, dry, 5
cold-air front moving southward from Canada 0
runs into a large mass of humid air moving

northward from the Gulf of Mexico. Most Lowest risk

tornadoes occur in the spring and summer

when fronts of cold air from the north penetrate

deeply into the midwestern plains.

As the large warm-air mass moves rapidly Figure 8 States with very high and high tornado risk in the continental United States. (Data from NOAA)
over the more dense cold-air mass, it rises

swiftly and forms strong vertical convection Data and Map Analysis

currents that suck air upward, as shown in 1. How many states have areas with a risk factor of 25 or higher? How many have areas with a risk factor

Figure 7. Scientists hypothesize that the rising of 20 or higher?

vortex of air starts spinning because the air near 2. What is the level of risk where you live? If you live in a far western state, does this mean you are guaran-

the ground in the funnel is moving more slowly teed never to see a tornado in your area?

than the air above. This difference causes the air

ahead of the advancing front to roll or spin in a Tropical cyclones are spawned by the formation cyclones that form in the Atlantic Ocean; those

vertically rising air mass or vortex. of low-pressure cells of air over warm tropical forming in the Pacific Ocean usually are called

Figure 8 shows the areas of greatest risk from seas. Figure 9 shows the formation and structure typhoons. Tropical cyclones take a long time to

tornadoes in the continental United States. of a tropical cyclone. Hurricanes are tropical form and gain strength. As a result, meteorolo-

gists can track their paths and wind speeds and

warn people in areas likely to be hit by these

violent storms.

Descending For a tropical cyclone to form, the tem-

cool air perature of ocean water has to be at least

27 °C (80 °F) to a depth of 46 meters (150 feet).

A tropical cyclone forms when areas of low

pressure over the warm ocean draw in air from

surrounding higher-pressure areas. The earth’s

rotation makes these winds spiral counter-

Severe Rising clockwise in the northern hemisphere and
thunderstorm clockwise in the southern hemisphere (Fig-

warm air Severe thunderstorms ure 7-3, p. 142). Moist air warmed by the heat
can trigger a number of the ocean rises in a vortex through the center

Tornado forms when of smaller tornadoes of the storm until it becomes a tropical cyclone
cool downdraft and (Figure 9).
warm updraft of air Rising
meet and interact updraft The intensities of tropical cyclones are rated
of air in different categories based on their sustained
Warm moist air drawn in wind speeds: Category 1: 119–153 kilometers
per hour (74–95 miles per hour); Category 2:
154–177 kilometers per hour (96–110 miles per
hour); Category 3: 178–209 kilometers per hour

(111–130 miles per hour); Category 4: 210–

249 kilometers per hour (131–155 miles per

hour); and Category 5: greater than 249 kilome-

ters per hour (155 miles per hour). The longer

a tropical cyclone stays over warm waters, the

stronger it gets. Significant hurricane-force

winds can extend 64–161 kilometers (40–100

miles) from the center, or eye, of a tropical

cyclone.

Figure 10 shows the change in the average

surface temperature of the global ocean between

Figure 7 Formation of a tornado or twister. Although twisters can form at any time of the year, the 1871 and 2000. Note the rise in this tempera-

most active tornado season in the United States is usually March through August. Meteorologists cannot ture since 1980. These higher temperatures,

tell us with great accuracy when and where most tornadoes will form. especially in tropical waters, may explain why

S50 SUPPLEMENT 8

4

Rising winds exit
from the storm at
high altitudes.

The calm central 3
eye usually is about 2

24 kilometers
(15 miles) wide.

Gales circle the eye at speeds
of up to 320 kilometers
(200 miles) per hour

Warm
moist air

1

Moist surface winds
spiral in toward the
center of the storm.

Figure 9 Formation of a tropical cyclone. Those forming in the Atlantic Ocean usually are called hurricanes; those
forming in the Pacific Ocean usually are called typhoons.

the average intensity of tropical cyclones has in- benefits of a tropical cyclone exceed its short- the barrier islands along the coast, allowing
creased since 1990. With the number of people term harmful effects. huge quantities of seawater to flood the bays
living along the world’s coasts increasing, the and marshes.
danger to lives and property has risen dramati- For example, in parts of the U.S. state of
cally. The greatest risk from hurricanes in the Texas along the Gulf of Mexico, coastal bays and This flushing of the bays and marshes reduced
continental United States is along the gulf and marshes normally are closed off from freshwater brown tides consisting of explosive growths of
eastern coasts, as shown in Figure 11 (p. S52). and saltwater inflows. In August 1999, Hurri- algae that had fed on excess nutrients. It also
cane Brett struck this coastal area. According to increased growth of sea grasses, which serve as
Hurricanes and typhoons kill and injure marine biologists, it flushed out excess nutrients nurseries for shrimp, crabs, and fish and provide
people and damage property (Figure 8-18, from land runoff and swept dead sea grasses food for millions of ducks wintering in Texas
p. 177) and agricultural production. Sometimes, and rotting vegetation from the coastal bays and bays. Production of commercially important spe-
however, the long-term ecological and economic marshes. It also carved out 12 channels through cies of shellfish and fish also increased.

Temperature (°C) 0.33 0.6 Temperature (°F) Figure 10 Change in global ocean tempera-
0.17 0.3 ture from its average baseline temperature from
1900 1920 1940 1960 1980 0 1880 to 2000. (Data from National Oceanic and
0 Year –0.3 Atmospheric Administration)
–0.17 –0.6
–0.33 –0.9 Data and Graph Analysis
–0.50 –1.2
–0.67 2000 1. In 1900, the global ocean temperature dropped
from its baseline temperature by how many
1880 degrees? (Give answer in both Centigrade and
Fahrenheit.)

2. Since about what year after 1980 have global
ocean temperatures consistently increased (with
all changes being positive)? What has been the
highest temperature increase since then, and in
about what year did it happen?

SUPPLEMENT 8 S51