Human beings and the natural
world are on a collision course. Human activities inflict harsh and often irreversible
damage on the environment and on critical resources. If not checked, many of our current
practices put at serious risk the future that we wish for human society and the plant and
animal kingdoms, and may so alter the living world that it will be unable to sustain life
in the manner that we know. Fundamental changes are urgent if we are to avoid the
collision our present course will bring about.
The environment is suffering critical stress:
Stratospheric ozone depletion threatens us with enhanced ultraviolet radiation at the
earth's surface, which can be damaging or lethal to many life forms. Air pollution near
ground level, and acid precipitation, are already causing widespread injury to humans,
forests, and crops.
Heedless exploitation of depletable ground water supplies endangers food production and
other essential human systems. Heavy demands on the world's surface waters have resulted
in serious shortages in some 80 countries, containing 40 percent of the world's
population. Pollution of rivers, lakes, and ground water further limits the supply.
Destructive pressure on the oceans is severe, particularly in the coastal regions which
produce most of the world's food fish. The total marine catch is now at or above the
estimated maximum sustainable yield. Some fisheries have already shown signs of collapse.
Rivers carrying heavy burdens of eroded soil into the seas also carry industrial,
municipal, agricultural, and livestock waste -- some of it toxic.
Loss of soil productivity, which is causing extensive land abandonment, is a widespread
by-product of current practices in agriculture and animal husbandry. Since 1945, 11
percent of the earth's vegetated surface has been degraded -- an area larger than India
and China combined -- and per capita food production in many parts of the world is
Tropical rain forests, as well as tropical and temperate dry forests, are being destroyed
rapidly. At present rates, some critical forest types will be gone in a few years, and
most of the tropical rain forest will be gone before the end of the next century. With
them will go large numbers of plant and animal species.
The irreversible loss of species, which by 2100 may reach one-third of all species now
living, is especially serious. We are losing the potential they hold for providing
medicinal and other benefits, and the contribution that genetic diversity of life forms
gives to the robustness of the world's biological systems and to the astonishing beauty of
the earth itself. Much of this damage is irreversible on a scale of centuries, or
permanent. Other processes appear to pose additional threats. Increasing levels of gases
in the atmosphere from human activities, including carbon dioxide released from fossil
fuel burning and from deforestation, may alter climate on a global scale. Predictions of
global warming are still uncertain -- with projected effects ranging from tolerable to
very severe -- but the potential risks are very great.
Our massive tampering with the world's
interdependent web of life -- coupled with the environmental damage inflicted by
deforestation, species loss, and climate change -- could trigger widespread adverse
effects, including unpredictable collapses of critical biological systems whose
interactions and dynamics we only imperfectly understand.
Uncertainty over the extent of these effects
cannot excuse complacency or delay in facing the threats.
The earth is finite. Its ability to absorb wastes
and destructive effluent is finite. Its ability to provide food and energy is finite. Its
ability to provide for growing numbers of people is finite. And we are fast approaching
many of the earth's limits. Current economic practices which damage the environment, in
both developed and underdeveloped nations, cannot be continued without the risk that vital
global systems will be damaged beyond repair.
Pressures resulting from unrestrained population
growth put demands on the natural world that can overwhelm any efforts to achieve a
sustainable future. If we are to halt the destruction of our environment, we must accept
limits to that growth. A World Bank estimate indicates that world population will not
stabilize at less than 12.4 billion, while the United Nations concludes that the eventual
total could reach 14 billion, a near tripling of today's 5.4 billion. But, even at this
moment, one person in five lives in absolute poverty without enough to eat, and one in ten
suffers serious malnutrition.
No more than one or a few decades remain before
the chance to avert the threats we now confront will be lost and the prospects for
humanity immeasurably diminished.