PINPOINTING GROWING THREATS
NATURAL RATES OF CHANGE
t
Lmmm
i/k
Greenhouse-Effect Vegetation Zones
Ice Age Vegetation 18,000 Years bp
0O Red numbers locate a geographic sampling of growing environmental threats. Green numbers mark improving situations.
Global Carbon Dioxide
Peru-Ecuador
Upwelling
Pastures of the Sea
People and Planet:
A Troubled
Partnership
Minnesota's
Boreal Forest
The Continental Garden
Population
Projections
Population Explosion
NATIONAL GEOGRAPHIC MAGAZINE
Produced by the Cartographic Division
National Geographie Society
And out of the ground made the Lord God to
grow every tree that ispleasant to the sight, and
good for food; the tree of life also in the midst
of the garden, and the tree of knowledge of
good and evil. Genesis 2:9
The Bible placed Adam and Eve in an
Eden they were soon to lose. Today
the approach of a new millennium
finds Homo sapiens at a historical
transition between a world inherited and one
profoundly different—a global biosphere
whose vital funetions we have altered.
While burgeoning human numbers place
unprecedented demands on farmland, forests,
and other resources, the expanding techno-
logical civilization that made those numbers
possible produces changes in the continents'
green skins of Vegetation and in the interac-
tions between atmosphere, land, oceans, and
living organisms that sustain virtually all life
on earth.
Massive changes have affected planetary
life since the earliest life-forms stirred. Conti
nents have moved, oceans and mountain
ranges have been made and unmade, ages of
heat and cold have waxed and waned, and
even the atmosphere has changed—as a result
of life itself—from one nearly devoid of oxy-
gen to one rieh in the life-fueling element.
Mass extinetions of species have accompanied
some eras of radical change, but always life
has survived and evolved.
Human dominance of the globe has ushered
in a new period of extinetions, primarily by
usurping natural habitats. Pollutants in the en-
vironment can wreak unforeseen results,
among them a global warming trend that
could push average temperatures higher than
any in the experience of the human race. A
"nuclear winter" caused by global war might
mean the end of most life-forms.
Yet along with potential self-destruction,
the present moment of technology's course
has delivered tools of knowledge never before
in hand, among them earth-sensing satellites
that daily report global conditions and Com
puters that log and assemble millions of simul-
taneous observations. Now able for the first
time to watch the global mechanism of life at
work, we must hope to comprehend and gain
control of our unwitting experiment with the
future of the earth.
OACID RAIN
O WATER POLLUTION
O POPULATION PRESSURE
©AIR POLLUTION
©OZONE CONCERNS
16,000 BC
2000
1000
AD I
250
500
750
1000
1250
EARLY HUMANS
ORIGINS OF AGRICULTURE
EARLY CIVILIZATIONS
GROWTH OF CITIES
PUBLIC HEALTH
AGE OF COLONIALIZATION
AGE OF RESOURCE USE
O WATER DIVERSION
©TOXIC WASTES
SPECIES EXTINCTIONS
0 FISHERIES DEPLETION
0 DEFORESTATION
0 DESERTIFICATION
PARKS AND REFUGES
1750 1800
ENVIRONMENTAL
LAWS AND TREATIES
1850
1900 1950 2000
FEAST AND FAMINE
CLIMATIC WARMING
EARTH FROM SPACE
THE OIL REVOLUTION
THE CHEMICAL ERA
Each slmulated map shows present
shorelines and reflects global patte
rather than site-specific informatior
MMligeide pro)Ceti on
reide projüction
ECUADOR
IOOÖ NATIONAL
lf1000 GEOGRAPHIC
liJOO SOCIETY
ENDANGERED
EARTH
GILBERT M. GROSVENOR, PRESIDENT AND CHAIRMAN
WILBUR E. GARRETT, EDITOR
JOHN B. GARVER, JR., CHIEF CARTOGRAPHER
TEXT BY DOUGLAS B. LEE,
NGS Senior Staff
Tomorrow's weather will be hotter.
Some regions will be drier, others can
expect greater preeipitation. This global
forecast is based on the increased release
ofeertain gases through human activity:
methane, nitrous oxide—and C02, which
contributes more to the growing green-
house effect than the other two com-
bined. At present rates ofgrowth the
effect of such gases could double by the
mid-21st Century, perhaps producing a
climate warmer by some four degrees
Celsius, leading ultimately to drastic
changes in Vegetation. The tropics and
some deserts reeeive greater rainfall.
Temperate climes become warmer and
drier; polar regions experience the
greatest warming. Vegetation will adjust,
flourishing where favored by tempera-
ture and moisture, struggling where
conditions deteriorate.
Tropical and
subtropical
rain forests
Cold-deciduous
broad-leaved
forests and
woodlands
Evergreen
needle-leaved
forests and
woodlands
Cold-deciduous
needle-leaved
forests and
woodlands
Subtropical
drought-deciduous
woodlands
Tundra
Arid grasslands
and shrub lands
Desert
Polar desert
and ice
Drought-seasonal
forests and
tall grasslands
Mesic
grasslands
First recognized as a regional issue in
Scandinavia, acid rain, snow, andfog kill
fish and other aquatic biota and damage
forests in Canada, the U. S., and western
and central Europe. An estimated 200,000
Square miles of forests in industrial
countries are damaged by acid rain or
other forms ofair pollution. A problem
that wafts across borders, it demands
international Solutions.
Fertilizers and Urban runoff increase Sedi
mentation and skew conditions in estuaries
and coastal waters, affecting fisheries.
Some rivers, like the Thames, have been
cleaned up, with native species reappear-
ing. The Caspian, Balde, and Mediterra-
nean Seas suffer from large coastal
populations and industry. Ports like Jakarta,
Bangkok, and Manila brew noxious stews.
Improvements have been made in Lake Erie.
Kenya's 4.1 percent growth rate—the
world's highest—will double its 23 million
people by 2005. At 2 percent, India would
reach 1.6 billion by 2075, rivaling China,
with a 1.4 percent rate, as the most popu-
lous country. Third World urban areas,
such as Manila and Säo Paulo, swellfrom
rural migration. Developed countries such
as West Germany have seen lowered birth-
rates and even populadon decline.
Mexico City ranks among the worst of
urban environments. Cleanup in Tokyo
has reduced smog. Once plagued London
and Pittsburgh purged their air. Industries
have blighted Vegetation near Sudbury,
Ontario, and in the Soviet's Kola Peninsu-
la. Motor-vehicle exhaust and power plant
emissions dirty the once pristine American
West. Cubatäo, Brazil, is one ofthe
world's most polluted communities.
Man-made chlorofluorocarbons
contribute to a deepening hole in upper-
atmosphere ozone—a filter of the sun 's
life-damaging ultraviolet radiation—ob-
served seasonally Over Antarctica. Deple-
tions also have been noted over the Arctic
and heavily populated mid-latitudes. In
contrast, industries and motor vehicles
contribute ozone to low-level pollution,
but it does not rise to upper levels.
Chief building block of organic matter, carbon is
also present in the atmosphere, oceans, soils, and rocks.
Through physical, chemical, and biologic processes,
carbon is transferred between these reservoirs, primarily as
carbon dioxide (C02). Deforestation and burning of fossil
fuel in the past two centuries have released carbon at an ac-
celerated rate. Increasing atmospheric C02 is the prime
mover in an antieipated rise in global temperatures that
many scientists believe has already begun (the greenhouse
effect). A substantialportion ofrecently released C02 is not
accounted for by current estimates of transfer rates. This
portion is probably taken up by ocean water and marine or
ganisms, and perhaps by increased rates of organic growth
on land. Satellite-generated estimates of planktonic biomass
and terrestrial photosynthetic potential could help in under-
standing life's role in long-term climate trends.
April 24,1981
Where offshore winds bring deep, cold,
nutrient-rich water to the surface, fields
of phytoplankton bloom off Peru* in
digital images from Nimbus 7 taken
three weeks apart. Red and orange by
the ocean-color index (above), the
massed bloom at far left is concentrated
by currents into plumes and eddies in
the near image. These shifting patterns
of wind, water, and marine life—along
a coast comparable in length to that
between Long Island and South Caro
lina—illustrate how rapidly the oceans
can change. Unmeasurable by tradi-
tional shipboard sampling, which would
take decades to provide a comparable
amount of data, the event was recorded
by satellite in just minutes.
*See on map above
The earth of our ancestors wore Conti
nental ice a mile thick as far south as the
Great Lakes when the most recent glacial
epoch peaked 18,000 years ago. Lower
sea-surface temperatures and an atmo
sphere averaging four to six degrees Cel
sius colder than ours today shaped a
global climate both more and less hospi-
table. A Vegetation model applied to an
Ice Age climate model indicates patterns
of Vegetation in which some desert areas
are wetter than at present, tropical rain
forests are smaller and in different loca-
tions, and temperate and subtropical for-
Life's green foundation, the chlorophyll-bearing plants of land and water harness
sunlight to produce organic matter through photosynthesis. At the first tier of the
aquatic food web, microscopic free-floating plants called phytoplankton tinge the
waters where they thrive, so that surface hues reveal the oceanic regions' relative
fecundity. For this portrait, ocean-color readings made by NASA's Nimbus 7 satel
lite were averaged over 18 months. Color-code reds and oranges indicate areas of
highest produetivity, such as the nutrient-rich polar seas, temperate and tropical
continental shelves, and wind-driven upwellings on the western coasts of the Ameri-
cas and Africa. Yellows and greens show moderately produetive regions in Pacific
and Atlantic equatorial currents, along contesting currents in the North Pacific, and
where winter turbulence stirs up nutrients for spring blooms in the North Atlan
tic and North Pacific. Light blues such as those off southern Africa show
less produetivity. Least fertile are mid-ocean gyres, in purple. Black areas
near the Poles are sea ice; those in the Pacific were not monitored.
OCEAN-COLOR INDEX
.1
Phytoplankton plgment concentrations
(milligrams per eubie meter of seawater)
Ocean-color data were derived from 20,000 images ac
quired between January 1979 and ]une 1980 by the
Coastal Zone Color Scanner (CZCS) on the
Nimbus 7 satellite.
The biosphere has complex in-
teractions by which a change
in one element of a natural
equation—such as greenhouse
warming in the biosphere—initiates
changes in other elements—ocean
volume, ice, cloud, and vegetative
cover, plus earth's reflectivity.
The workings of global mechanisms
are not well-enough known to
predict the outcome of human-
induced changes.
For 3.5 billion years life and its
host planet have conspired in shap-
ing the other's evolution. For eons
microscopic creatures have trans-
formed the chemistry of oceans, at
mosphere, and soils. Vegetation
helps determine erosion rates, while
physical forces, in turn, help shape
the patterns of growth.
Previous climatic shifts have
occurred over lengths of time that
allowed flora and fauna to adjust
as overall patterns moved. Judged
against natural change, man-made
global effects bring results at light-
ning speed—with consequences feit
in just two industrialized centuries.
This rapid change and such new ele
ments as ozone-destroying chemicals
not naturally present hamper our
ability to predict the extent or dura-
tion of long-term effects.
The biosphere's pulse flutters in
cycles ranging from seconds to tens
of millennia. Plankton may bloom
for a day and never be seen by a re-
search vessel; trees grow and fall
while a forest lives on as an entity.
Thus the new space-based ability to
measure global change looms large
in the trial of nature's latest biologi-
cal innovation—humankind, with its
capacity to understand and influence
the biosphere.
ests and woodlands are more widespread.
Tundra and high-latitude forests occur
much farther south in the Northern
Hemisphere and claim the southern end
of South America. Inadequate Informa
tion on climate precludes depiction of
Antarctic data on these maps.
April 3,1981
ECUADOR
PERU
Humans emerge from Ice Age as skilled,
equipped hunter-gatherers. Neolithic
revolution from food gathering to pro
ducing occurs.
World population 4 million
Beginning of wärmest period in 100,000
years. Domestication oferops and live
stock. Invention ofthe plow.
Hippocrates leaves a legaey of medical
ethics.
'ere derived from historical estimates
Romans advance public sanitation.
200 million
Polynesians spread across Pacific.
Plato recognizes deforestation as causing
erosion. Aristotle describes the natural
world.
Pliny the Eider records observations on
natural history.
Warm spell quickens Norse exploration.
360 million
Moldboardplow and horse collar ex-
pand forest Clearing and cultivation.
William the Conqueror establishes royal
game preserve in England. Marco Polo
reports nationwide game laws in China.
Once forested regions of Africa, Asia,
and Europe feit the hand of humans
far back in prehistory, when hunter-
gatherers learned to set fires to drive
game and clear brush—still practiced by
semi-nomadic tribes in Africa.
The digging stick marked the tool-using
creature's departure from previous evo-
lutionary experience. Planting and har-
vesting, humans no longer needed to
move to eat. Settlements appeared; ani-
mals and plants were domesticated.
Cultures coalesced on the Tigris-Euphrates,
the Nile, and the Indus, giving rise to the
earliest civilizations. Organized warfare
arrived. Irrigation fed the Fertile Cres-
cent; resulting salinization took an early
environmental toll.
The Fertile Crescent brought the world its
first cities in the fourth millennium B.C.,
as technology engendered more sophisti-
cated societies. The sphere of early cities
was the adjacent countryside; later they
grew from wider trade and imperialism.
Rome's baths, aqueduets, and sewers
were widely copied. Sanitation has been a
major factor in public health improve
ments and lower mortality rates. Crowd-
ing and squalor have bred epidemics
throughout history.
The world crossed into its modern age
with Columbus's voyage in 1492. Euro
pean powers established colonies and
trade routes around the globe. Interconti-
nental movements of people, plants,
animals, and diseases rose sharply.
Industry moved into the wilderness in the
19th Century. Commercial logging ex-
panded; whalers combed the seas. Rail-
roads brought mechanized farming to
new regions. Frontiers are exploited to
day in Alaska, the Amazon, and Siberia.
Tapped for agribusiness, the mighty Colo
rado River reaches the sea as a trickle.
Stream diversion in China emptied a lake,
Lop Nur. A Soviet river-diversion scheme
that threatened the regional ecological bal-
ance was abandoned. The Nile's Aswan
High Dam has depleted farmland ofsilt
and the eastern Mediterranean of nutri
ents. Overused aquifers are dropping in
Africa, Asia, and North America.
New Jersey's Meadowlands bear the poi-
sons of megalopolis. At New York's Love
Canal, a sickened Community was evacu-
ated from atop a toxic waste dump. Part of
San Diego Bay holds extremely high con
centrations of PC Bs. Irrigation has con
centrated heavy metals in the Beijing-
Tianjin basin and selenium at a California
wildlife refuge. Cleaner technology ended
mercury poisoning at Minamata, Japan.
o RADIATION PERILS
Disaster at the Soviet Union's Chernobyl
Nuclear Power Plant in 1986 caused the
Single greatest industrial release ofradia-
tion, dwarfing an accident at Three Mile
Island in Pennsylvania. Waste disposal
also poses unanswered problems. Several
nations test nuclear weapons. Bikini Is
landers cannot yet return to a home con-
taminated by U. S. testing. Japanese atom
bomb survivors suffer radiation effects.
Deforestation as in Brazil, Madagascar,
and Southeast Asia is the prime cause for
the loss of thousands of species a year.
Refuges in Africa, North America, and
Asia face isolation as biological "islands.
Introduced Nile perch devastate Lake
Victoria's more than 300 species. Black
rhinos are nearly extinet, Florida maria-
tees endangered; but sea otters, gray whales,
and whooping cranes have come back.
In the past 40 years, overfishing and natu
ral causes have combined to produce
alarming declines in certain Stocks ofan-
chovies, sardines, and cod, some followed
by resurgences. Pollution also takes a toll.
Shellfish dwindle on U. S. coasts. Fisher-
men off the Philippines bomb and poison
reefs. Antarctic krill harvests may under-
mine the food web. U. S. laws have low
ered dolphin tolls in Pacific tuna harvests.
Life 's greatest storehouse, tropical forests
shrink annually by an estimated 80,000 of
their total ten million Square miles through
expanding agriculture, logging, and devel-
opment. Demand for fuel has denuded Af-
rican woodland and slopes in Haiti and
Nepal—where erosion, landslides, and
floods have increased and no cover may
remain by 2020. Costa Rican parks pre
serve tropical ecosystems.
Prolonged drought in the Sahel has coin-
cided with population growth, overgraz-
ing, and the closing ofpolitical boundaries
to disrupt patterns of nomadic life. Result
ing pressure on marginal land has sped the
spread of desert conditions. Salinization
strangles irrigated fields in Australia.
Israel has experienced notable success at
revegetating deserts, and China has
instituted mass plantings for reclamation.
»ARY WATERS CANOE AREA
SUPERIOR NATIONAL FOREST
BOUNDARY WATERS CANOE AREA
Mollweide projection
LAND-VEGETATION INDEX
First study of mortality rates
from English parish records
The concept of parks as national assets
became reality in Yellowstone in 1872.
National forests were first set aside in the
U. S. in 1891; federal wildlife refuges in
1903. In 1980, 160,000 Square miles of
Alaska wilderness reeeived protection.
James Watt's steam engine spurs indus
trial revolution. All but one of 13 Ameri
can Colonies have legal hunting seasons.
The 1899 Rivers and Harbors Act first
legislated U. S. control of water pollut
ants. The 1916 Migratory Bird Treaty be
tween the U. S. and Canada initiated
international conservation. The 1970s
saw new environmental laws.
Henry David Thoreau publishes Wai
den Charles Darwin writes The Origin
of Species. Pennsylvania oilstrike.
DDT use banned in U. S. "Nuclear win
ter" recognized as possiblt aftermath of
Dust Bowl in U. S. mobilizes national nuclear war.
resources for conservation. First use of
DDT. Nuclear fission achieved.
World food produetion could feed more
than present numbers, but economic in-
equities, politics, and indifference keep
about 10 percent of humanity critically
malnourished. Famine induced by politi-
cal upheaval and war is still a reality.
How fast, how far, and howlong climate
will warm are unknowns asaverage tem
peratures surpass historical ranges: The
hottest years in this Century occurred in
the 1980s, the hottest decadeon record.
Agriculture could shift and s:a levels rise.
First photographed in its entirety from a
Lunar Orbiter in 1966, earth is a prime
target of space research. In the 1990s the
U. S. plans a new generation of earth-
sensing satellites and a space Station for
sustained human Observation.
"We think of Vegetation as static. It's
vibrant in a way we don't understand,"
says Dr. Forrest Hall of the National
Aeronautics and Space Administration.
A NASA Landsat satellite monitored
boreal forest in northern Minnesota*
to delineate internal change over a ten-
year period. A color-coded mosaic Charts
changed and unchanged areas of Veg
etation. Surprisingly, natural processes—
normal vegetative succession as well as
fires, old age, insects, and wind—altered
50 percent of the protected Boundary
Waters Canoe Area in ten years. Still,
rates of change from mature forest to
deforested and regenerating areas were
five to ten times lower there than on
logged land outside its borders.
*See on map above
Mongols depopulate parts of Asia and
Europe and contribute to the spread of
bubonic plague. The "Black Death re-
duces Europe's 80 million by a third in
only five years.
350 million
A Pennsylvania oil strike launched the
modern oil industry in 1859. In 1885 coal
surpassed wood as the main source of
U. S. energy, to be replaced by oil in
1950. The economics of prices and use
indicate perhaps a Century's supply.
Columbus opens the age of
colonialization. 500 mUlion
Spraying of DDT in the 1940s began
widespread chemical control of the envi-
ronment and major shifts in public health
and agriculture. Synthetics brought revo-
lutions in industry and such aspects of
daily life as housewares and clothing.
14 billion-pr'
Unchanged forest
Maturing forest
Areas of regeneration
following disturbance
(flre and logging)
Areas of natural
regresslon
(death and disease)
Areas of recent
human-induced
disturbance (logging)
Clouds
Cloud shadow
Water
Design: HAROLD E. ABER, JR., Director; John F. Dorr, Bob Pratt; Research:
ALICE T. M. RECHLIN, Director; Harry D. Kauhane, Debbie J. Gibbons,
Gaither G. Kyhos, Jan Holderness, Carrie E. Pinkerton; Produetion: LEO B.
ZEBARTH, Director; David P. Beddot, Charles F. Case, Roland R. Nichols,
Kevin P. Allen, Micki A. Moran; Prin :ing and Quality Control: JOHN F.
SHUPE, Director; Elie Sabban, Edward J. Holland; Contributing Staff: Stephen
P. Wells, Kelly J. Crisp, Scott T. Fort, Jonathan E. Kaut, Gretchen N. Kuhn,
Stephanie F. Lane, Eric A. LindstromJon A. Sayre, Sr., Robert F. Shapiro,
George E. Stuart, Thomas A. Wall
Principal Consultants: Daniel B. Botkin, Professor of Biology and
Environmental Studies, University of California at Santa Barbara; Gene Carl
Feldman, National Aeronautics and Space Administration (NASA), Goddard
Space Flight Center, Space Data and Computing Division; Forrest G. Hall and
Compton J. Tucker, NASA, Goddard Space Flight Center, Laboratory for
Terrestrial Physics; Carl Haub and Al*x von Cube, Population Reference
Bureau, Inc.; Katharine C. Prentice, NASA, Goddard Space Flight Center,
Institute for Space Studies
Additional Sources: University of California at Santa Barbara: Edward A.
Keller, Professor of Geology and Environmental Studies, Frank W. Davis,
Assistant Professor of Geography, and John E. Estes, Professor of Geography.
NASA, Goddard Space Flight Center, Space Data and Computing Division:
Raul Garza-Robles; Laboratory for Oceans: Wayne E. Esaias, Charles R.
McCIain, Jane A. Elrod, and Guillermo P. PodestaInformation Processing
DivisionInstitute for Space Studies: Dorothy M. Peteet, Jasmin G. John,
Patrice D. Palmer, and Jeffrey A. Jonas. University of Miami, Rosenstiel School
of Marine and Atmospheric Science: Robert H. Evans, Professor of Satellite
Oceanography, James W. Brown, H. Mark Carle, and Susan E. Walsh. Science
Applications Research, Inc.: Donald E. Strebe! and Scott J. Goetz. Butler
University: Orie L. Loucks, Director of Holcomb Research Institute
As infant and childhood survival
rates improve with public health,
growing numbers reach childbear-
ing age; life expectancies also in
crease. The doubling period for
world population has shortened
from centuries to mere decades.
Three ranges project the size of
the future population; each as-
sumes that birthrates in the next
half Century will fall enough to
lead to zero growth. j
j billion
6 billion
10 billion
Population projections are based on United
Nations assessments
1/
y 8 billion
5 billion
China reaches a billion population in
1981. First case of acquired immune defi-
ciency Syndrome (AIDS) identified.
China suffers 30 million deaths in tur-
moil of Great Leap Forward.
Penicillin manufactured and distributed.
Infectious-disease rates lowered.
World War I ends; 15 million dead.
World War II ends; 50 million dead.
Edward Jenner shows immunity from
smallpox through inoculation; Thomas
Malthus links population growth and
Potato famine initiates large-scale Irish
Immigration to New World. Louis Pas-
teur and Robert Koch help prove the
germ theory of disease.
2 billion
resources.
1 billion
The five billion human beings alive
today represent probably 6 to 7 percent of
all who have lived in our species' 350,000-
to 100,000-year genealogy. From perhaps
four million at the peak of the last Ice
Age, growth accelerated slowly until the
industrial revolution 18,000 years later.
After a global population surge, birth
rates declined in developed countries,
and today their populations are near, and
even below, zero growth. After World
War II quantum improvements in public
health were swiftly exported to less devel
oped countries, dramatically lowering
death rates. Declines in birthrates often
lagged behind, causing unprecedented
population growth. A majority of man-
kind still lives in an agrarian, preindustri-
al condition, with birthrates approaching
Kenya's eight children per woman. To-
day's soaring numbers occur almost whol-
ly in nations least able to afford them,
where masses live on the edge of survival,
often on marginal or unsuitable land.
World's first national park dedicated at
Yellowstone. U. S. begins to designate
national forests.
CO2 measurem ent l
Rachel Carson's
documents DDT's hazards, initiates
environmental movement.
Of all terrestrial living matter, 95 percent is Vegetation. The Chlorophyll content in
dicates the potential for new produetion. The NOAA 7 satellite recorded worldwide
land-surface radiation in the visible and near-infrared bands to estimate Chlorophyll
and leaf mass. Three years of daily global readings went into this image to map re
gional average potential for photosynthesis throughout the continents' green man-
tles. Combined with the presentation of ocean plant life, it gives us a first-of-a-kind
view of the produetive potential of earth's vegetative biomass. A color-coded index
shows highest potential produetion in darkest greens, primarily in rain forests. Next
come other tropical and subtropical forests, temperate forests and farmlands, and,
surprisingly, some drier regions such as savannas and pampas. Seasonal croplands in
North America's Midwest and the Soviet steppes show lower potential for
new growth, while boreal forests and the dry Australian outback rank lower
still. Deserts, high mountains, and Arctic regions reflect barren
conditions. Inland waters appear red.
o 1
Minimum Photosynthetic potential Maximum
Land-vegetation patterns were derived from data acquired in
15,000 orbits between April 1982 and March 1985 by the
Advanced Very High Resolution Radiometer (AVHRR)
on the NOAA 7 satellite.
