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1
introduction
As the human race prepares to venture into a new century,
conversations and news reports are peppered with references to
our "fragile and endangered planet." This phrase almost cer-
tainly exaggerates the case. The earth is 5 billion years old, and
over the eons it has endured bombardment by meteors, abrupt
shifts in its magnetic fields, dramatic realignment of its land
masses, and the advance and retreat of massive ice mountains
that reshaped its surface. Life, too, has provect resilient: In the
more than 3.5 billion years since the first forms of life emerged,
biological species have come and gone, but life has persisted
without Interruption. In fact, no matter what we humans do,
it is undikely that we could suppress the powerful physical and
chemical forces that drive the earth system.
Although we cannot completely disrupt the earth system,
we do affect it significantly as we use energy and emit pollu-
tants in our quest to provide food, shelter, and a host of other
products for the worId's growing population. We release chem-
icals that gnaw holes in the ozone shield that protects us from
harmful ultraviolet radiation, and we burn fuels that emit heat-
trapping gases that build up in the atmosphere. Our expanding
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Representative terms from entire chapter:
environmental change
2
INTRODUCTION
numbers overtax the agricultural potential of the land. Tropi-
cal forests that are home for minions of biological species are
cleared for agriculture, grazing, and logging. Raw materials are
drawn from the earth to stoke the engines of the growing world
economy, and we treat the atmosphere, land, and waters as re-
ceptacles for the wastes generated as we consume energy and
goods in our everyday lives.
Scientific evidence and theory indicate that as a result of
such activities, the global environment is undergoing profound
changes. In essence, we are conducting an uncontrolled experi-
ment with the planet.
The changes facing the planet today are distinguished from
previous changes by the scale and pace with which they are oc-
curring or are likely to occur. Over the geologic past, conditions
in Me atmosphere, ocean, and biosphere have for the most part
followed natural cycles. Now, human activities are a significant
force driving changes in the gIobai environment.
This book is intendec! to present briefly the current state of
scientific knowledge about the changes under way in the global
environment. Its organization, inspiration, anti, to a substantial
extent, its content derive from the Forum on Global Change
and Our Common Future, which took place in May 1989 in
Washington, D.C. (see Appendixes A, B. and C), and which
was jointly sponsored by the National Academy of Sciences,
the Smithsonian Institution, the American Association for the
Advancement of Science, and Sigma '
INTRODUCTION
3
case of the acid deposition that alters soil chemistry and affects
the natural chemical balance of many of the world's waterways
and lakes, the effects of pollutant emissions in one part of the
world can be felt half a continent away. The chIorofluorocar-
bons (CFCs) produced and emitted by industrialized countries
rise to the stratosphere, where, like other pollutants, they dis-
perse without regard to political or geographical boundaries.
When forest land is cleared and used for grazing cattle or grow-
ing crops, plant and animal communities are disrupted (or, for
species with limited habitat, eliminated).
Our activities have already caused changes in the compo-
sition of the earth's atmosphere, most notably increased atmo-
spheric concentrations of trace gases such as carbon dioxide,
methane, nitrous oxide, and chIorofluorocarbons. From the be-
ginn~ng of earth's history, certain of these trace gases have had
an unportant role in the principle that is known as the "green-
house effect." In a fashion crudely analogous to the function
of Me glass panels of a greenhouse, the gases keep some of the
earth's heat from escaping through the atmosphere and thus
have the potential to warm the earth's surface temperature. At-
mospheric concentrations of carbon dioxide after water vapor
the most plentiful greenhouse gas- have increased significantly,
mostly because humans have burned vast quantities of fossil
fuels In the past 100 years, releasing carbon dioxide in the pro-
cess. As forests, which absorb carbon dioxide as they grow, are
cleared and the feDed trees and brush are burned or decay, the
massive amounts of carbon a forest ordinarily stores are released
to the atmosphere.
If rapid warming of the earth's surface from changes in
the composition of the atmosphere occurs as scientists warn
is within the realm of possibility-other global and regional
changes could result. Sea level could rise as ice caps melt and
Me ocean expands from the extra heat, and agricultural belts will
shift. Forests and other ecosystems may be torn apart as both
plant and animal groups respond to vastly altered temperature
and hydrological conditions, and as various kinds of plants
adjust differently to increased carbon dioxide levels. Rapid
4
INTRODUCTION
changes in climate could cause regional food shortages, cre-
ate waves of environmental refugees, and threaten the security
of other countries as the effects of the turmoil ripple through the
world economy. This is not to say that all changes will be bad.
Some northern high-latitude regions could witness increaser}
agricultural yields and benefit from a warmer climate.
With the physical, chemical, and biological changes in the
earth system that humans are causing, more surprises like the
discovery of the antarctic ozone hole cannot be ruled out. At-
mospheric chemists point out that despite years of study, no
one predicted that a hole would form each year in the protective
ozone layer high in the atmosphere over Antarctica. Unexpected
events of comparable or greater gravity are likely to continue to
appear even as scientific understanding evolves.
"Nature seems to be running a fever. We are the flu," ob-
served William Ruckelshaus, former head of the U.S. Environ-
mental Protection Agency, at the Forum on Global Change and
Our Common Future in May 1989. "Our goal is not so much
to manage the planet earth as to make ourselves less like a
pathogen and more like those helpful bacteria that dwell in our
own guts."
- -r
The transformation of the global environment is driven by
ever-greater numbers of people, increasing economic develop-
ment, and its attendant increase in industrial activity and con-
sumption of energy by humans. Of these factors, population
growth is the most easily quantified. Since 1900, the number of
people has more than tripled. In 1987, the 5 billionth member
entered the human family. Our numbers are increasing today
by about 90 million per year, and, according to United Nations
(U.N.) projections, are expected to reach 10 billion or more by
the end of the coming century. Ninety-five percent of these
people will be born in the poor countries of today's developing
world.
While population has increased, so have standards of liv-
ing for many of the earth's people, consumption of fossil fuels,
and expansion of the world economy. These changes have al-
lowed astonishing improvements in human welfare, but at a
INTRODUCTION
5
cost. Unfortunately, many of the processes that produce gains
degrade the environment and deplete the ecological capital the
soils, forests, species, fisheries, and water resources-on which
humanity relies.
People in the richer, developed countries, with only one
quarter of the worId's population, consume most of the worId's
energy. They command about 80 percent of the worId's wealth,
use most of its natural resources, and generate the most waste.
Most of the greenhouse gases and chemicals that are changing
the composition of the atmosphere and thus contributing to
the projected climate change and to other changes such as acid
deposition have been emitted by inclustrialized nations in the
Northern Hemisphere.
People in the developing countries, with three quarters of
the worId's population, have less than one quarter of the wealth.
But the millions of poor people in the developing world also con-
tribute to resource depletion anct environmental stress. The poor
and hungry are often compelled to destroy their environment-
by cubing down forests and depleting soils in order to survive.
In the developing world, improved standards of living can
break the cycle of rapid population growth and the environ-
mental hazards it engenders. The experience of country after
country has shown that economic development, when paired
with better opportunities for employment and education, even-
tually leads to lower birth rates. The catch, as Ruckelshaus
noted at the forum, is that, "If the four-fif~s of humanity now
in developing nations attempts to create wealth using the meth-
ods of the past, at some point the result will be unacceptable
world ecological damage." Developing countries now account
for about one quarter of all greenhouse emissions. If the same
roads to prosperity are followed that were taken in the past by
developed nations, this share could double by the middle of the
coming century.
The prospect of unchecked global environmental change
thus raises troubling questions about equity that world leaders
can no longer ignore. Since sacrifice and gain will be unequally
distributed, what is the responsibility of the "have" nations that
6
INTRODUCTION
created many of the problems to the "have not" nations that
seek to develop in order to meet the needs of their people?
Is it equitable to expect the poorer nations in their pursuit of
Improved standards of living to hold to stringent environmental
controls that the developed nations did not have to contend
with in their periods of rapid industrial growth? And what is
the responsibility of people now living to future generations?
The existing disparities between We rich countries of the
North and the poor countries of the South and the lack of capital
and infrastructure in poor countries to cope with rapid changes
in environmental conditions are prompting John Holdren, of
the University of California at Berkeley, Jessica Mathews, of the
World Resources Institute, and many other prominent political
analysts, world leaders, and politicians to reconsider the na-
ture of possible future threats to world peace and security. For
decades the main threat to security has been widely associated
with the potential for conflict between East and West, with the
nuclear arms race, and with the U.S./Soviet tensions centered
in Central Europe. In the late 1980s, as epochal changes in Cen-
tral Europe forced the world to rapidly revise its perceptions of
the nuclear threat, the potential risks arising from changes in
the global environment began to ciann attention. "The poten-
tial explosion of tensions deriving from global environmental
change is clearly going to be aggravated by the widespread
perception that the biggest burdens will fall on the developing
countries of the South and Mat the principal culprits in gen-
erating these problems, through both action and inaction, are
in the developed countries of the North," said Hoiciren at the
forum. International dialogue that is currently under way rep-
resents the opportunity for nations~eveloped and developing
alike to overcome these tensions and attack together common
concerns about the global environment.
The future of the global environment and the consequences
of the changes in store assumed new currency, at least within
political circles, in 1987 when the World Commission on En-
vironment and Development issued its path-breaking report,
Our Common Future. (The World Commission is also known as
INTRODUCTION
7
the Brundtiand Commission after its chairperson, Gro Harlem
BrundtIand, former Prime Minister of Norway isee Afterword,
p. 1471.) The commission, created in 1983 by the U.N. General
Assembly, was a special independent organization that included
representatives from 22 countries, a majority of them develop-
ing countries. Over a 3-year period, the members tackled We
question tacitly posed by the General Assembly: Is it possible to
meet the needs of the 5 billion people alive today without com-
prom~sing the ability of future, ever more populous generations
to meet their own needs?
After exhaustive study and analysis, the commission an-
swered with a heavily qualified "yes." The grim but very real
prospect that the future of humanity depends on an environ-
ment ever more polluted, degraded, and devoid of the ecolog-
ical resources requires} to ease poverty and hardship could be
averted if processes of economic and social development are
transformed. The commission invoked the concept of sustain-
able development to describe a means by which economic and
social progress could be achieved without compromising the
Integrity of the environment.
Sustainable development is not a new concept, but its promi-
nence in Our Common Future has stimulated governments,
policymakers, economists, and moralists throughout the world
to reconsider its Implications. Of particular interest is the
BrundtIand Commission's central theme: the integration of en-
vironment and economy. As BrundtIand pointed out in her
keynote address to the forum, "Only growth can eliminate
poverty and create the capacity to solve environmental prob-
lems. But growth cannot be based on overexploitation of the
resources of developing countries. It must be managed to en-
hance the resource base on which these countries all depend."
If this new doctrine is to govern future approaches to growth
and development, painful choices will be required in how we
exploit resources, direct investments, develop technologies, and
organize our Institutions. The wealthy nations must recognize
that their continued prosperity depends in part on maintaining
the earth's ability to supply food ant] other resources and that
8
INTRODUCTION
this in turn requires increased prosperity and security in the
developing world. Our Common Future heightened awareness
of some widely discussed, and thought-provoking, arguments.
One suggestion, for example, is that it may be time to price
goods to reflect the environmental costs of their production and
use. Gasoline, for instance, might be priced to reflect the costs
of the damage that burning the fuel causes through pollution
and increased risk of climate change. Likewise, the price of fer-
tilizer might reflect the cost of cleaning up the water supplies
it pollutes. In addition, Our Common Future suggests that it
may be appropriate to restructure institutions to reflect environ-
mental priorities. This would mean that environmental aspects
of policy would be considered at the same time as questions
of economics, trade, energy, and agriculture, and by the same
national and international institutions. Environmental agencies
would be given more power to redirect policies that now lead to
environmental degradation. Economic, trade, and other govern-
ment agencies heavily endowed with money and power would
be mandated to develop policies that encourage sustainable de-
velopment and would be responsible to their governments for
the environmental consequences of their policies and budget
allocations.
The BrundtIand Commission emphasized that if the pace of
global change is to be checked, developing countries are likely
to need fresh infusions of financial support in the 1990s to pay
for efforts to reduce rates of population growth, to restore and
maintain natural resources, and to adopt modern technologies
that are less polluting than the ones already outdated in the
industrialized world. Our Common Future, as well as many
political and economic analysts, points out that the question of
increased aid cannot be taken seriously until the debt situation
is resolved. Debt remains an urgent problem facing developing
countries, particularly in Latin America and Africa. The World
Bank reports that in 1988 the 17 most indebted nations paid
developed nations and multilateral agencies $31.! billion more
than they received in aid.
As governments, industrialists, scientists, and the public
INTRODUCTION
9
consider the implications of suggestions such as those above, it
is increasingly apparent that the decisions that will make these
adjustments possible will require tighter connections between
science and policy.
The earth has already been committed to major environ-
mental change in the years ahead. The elevated concentrations
of greenhouse gases already emitted through human activity
will persist for many centuries, no matter what we do. The
chIorofluorocarbons in the atmosphere today will continue to
deplete the ozone shield for centuries. Complex tropical for-
est ecosystems once cleared can regenerate slowly at best. The
magnitude and rate of change will depend on whether societies
clecide to act to slow the atmospheric buildup of carbon dioxide
and other trace gases, reverse deforestation, and cut pollutant
emissions. Steps required to slow the pace of change, and for
adapting to it if need be, will be costly, but so may be the costs of
inaction. As climatologist Stephen H. Schneider, of the National
Center for Atmospheric Research, cautions, if society chooses
to wait another decacle or more, "we face a higher risk that we
will have to adapt to a larger amount of climate change than
if actions to slow down the buildup of greenhouse gases were
pursued more vigorously today."
In the face of much scientific, social, and political uncer-
tainty, encouraging signs abound. Demographers report, for
instance, that birth rates in many countries are declining. Forty-
nine nations have ratified the Montreal Protocol on Substances
That Deplete the Ozone Layer, which calls for a 50 percent re-
duction in chIorofluorocarbon production from 1986 levels by
1999 and provides a mode} for cooperation that spans national
boundaries and interests. The amount of energy and raw mate-
rials required to produce a given amount of goods is decreasing
in some countries, including the United States.
Scientists can provide information on which to base deci-
sions, but whether to act to slow the pace of environmental
change is a social judgment, not a scientific one. Among sci-
entists there is a broad consensus that even in the face of in-
complete or conflicting data, measures to ease adaptation to the
0
INTRODUCTION
potential changes, or even to reduce the rate of changes already
under way, are possible and advisable. Steps such as improving
energy efficiency and developing alternatives to fossil fuels not
only would slow the rate of warming but also could buy cru-
cial time to study climate change and assess the unpacts. The
presidents of the National Academy of Sciences, the National
Academy of Engineering, and the Institute of Medicine advised
then President-elect George Bush in 1988 that, "While global en-
vironmental change cannot be stopped, the pace of change can
be slowed. We cannot buy absolute security against environ-
mental risk, however much we are willing to pay, but we may
be able to reduce environmental damage and risk markedly by
prudent policy actions" (see Appendix D).
In the encI, the outcome will depend on political will. The
social, political, and economic changes would be enormous. Yet
government leaders are increasingly attuned to the gravity of
the hazards facing society as environmental degradation pro-
ceeds. They are talking at the highest levels, and many are
struggling to translate acceptance of a set of values, such as
the need to protect the environment, into action. In the United
States, our environmental statutes are among the most stringent
in the world, and the people repeatedly express their desire
for increased environmental protection. Yet this country is the
largest emitter of greenhouse gases, and environmental pollu-
tion continues to be a major problem.
The chapters that follow provide the backdrop of scientific
information on which the political decisions ultimately will rely.
The complexities of earth system science, the lessons derivecl
from the earth's history, and the modern forces driving changes
in the global environment are explored in the first part of this
book, "The Earth as a System." The second part, "The Faces
of Global Environmental Change," describes some of the trans-
formations projected or under way. These include the prospect
of a warmer global climate, potential changes to the worId's
food production systems and water supplies as climate changes,
and the likelihood that sea level will rise as the climate warms
INTRODUCTION
11
and how this may affect the world coastal zones and their in-
habitants. Subsequent chapters examine other human-induced
changes to the global environment, including the threat to the
earth's ozone layer, deforestation and dwindling genetic diver-
si$y, and how acid deposition affects our forests, lakes, and
waterways. (Appendix A contains a selected list of additional
reacting on global environmental change.)
The environmental challenges described are difficult ones
for a world already grappling with other costly and more ob-
vious problems of economics, security, and public health. But
as the following chapters demonstrate, global environmental
change may well be the most pressing international issue of the
coming century.
