Foreign Service Journal March 1999
I believe that most people _ by which I mean not only most members of
the public, most journalists, and most policy-makers, but also a great many
natural scientists, social
scientists, and technologists _ continue to underestimate the problem of
human-induced disruption of global climate. As a result, they continue to
underestimate the urgency of taking
appropriate preventive action ... and the likely costs of not doing so.
There are six important reasons for this underestimation of the climate
threat and of the need to take early action against it. In this article,
I will elaborate on each of these reasons in turn.
1. Human well-being is more dependent on climate control than most people
think.
Environmental conditions and processes are no less critical to human well-being
than economic conditions and processes are, although ecologists, geochemists,
and atmospheric scientists have been less effective publicists for the services
they study than economists have and in fact the economic and environmental
dimensions of well-being are tightly intertwined.
Nature, not factories, builds the soil; and nature, more than factories,
provides the wherewithal to fertilize it. Nature, more than dams and ditches,
makes water available when and where it is needed. Natural processes, more
than technological ones, maintain the composition of the air we breathe,
purify the water we drink, and recycle the wastes we generate. Nature, more
than manufactured pesticides, controls most crop pests. And environmental
conditions, not doctors
and drugs, keep most disease organisms under control. We, and the environmental
processes that provide these services for us, are almost completely vulnerable
to the vagaries of the climate, which are kept for the most part within
tolerable limits by global climatic machinery we have become powerful enough
to disrupt but not clever enough to control.
The patterns of climate disruption that appear to be emerging as a result
of growing human emissions of greenhouse gases to the atmosphere are likely
to affect the productivity of farms and forests and fisheries, the frequency
and intensity of floods and droughts and heat waves, and the geographic
patterns of human disease. They are likely to entail a substantial increase
in sea level, with associated increases in storm damage to coastal property
as well as flooding of coastal lowlands and even entire low-lying island
nations. The species composition of something in the range of 30 percent
of the world's forests is likely to be significantly altered between now
and the end of the next century, and extinctions of species and biological
populations are likely to accelerate.
The consequences of climatic change will not be uniformly distributed, and
many of the details of the distribution are not yet predictable. Some regions
will experience improvements in relation to some of the conditions mentioned,
rather than deterioration. But the high degree of adaptation of human societies
to the climatic conditions of the recent past, coupled with the limited
capacity of societies and ecosystems to adjust to new conditions as rapidly
as climate is likely to change over the next century, mean that harm will
probably be far more prevalent than benefit.
2. Climate disruption is further along and harder to reverse than most
people think.
Not in dispute is that the global atmospheric concentration of carbon
dioxide, which is the most important of the heat-trapping ("greenhouse")
gases emitted in significant quantities by human activities, had increased
by 1998 to about 30 percent above its pre-industrial level (to 365 ppmv
_ parts per million by volume, from 280 ppmv). This increase has closely
tracked the increase in fossil-fuel combustion worldwide. Deforestation
also appears to have been a significant contributor, although less important
in recent decades than fossil-fuel combustion. Other greenhouse gases _
methane, chlorofluorocarbons, and nitrous oxide _ have also been accumulating
in the atmosphere, as have sunlight-reflecting particles that partly offset
the heat-trapping effects of the greenhouse gases.
Analyses of weather records from around the globe reveal a pattern of
changes that most serious students of this issue regard as an increasingly
clear "fingerprint" of anthropogenic greenhouse-gas increases
on the climate. These changes include increases in the global mean near-surface
air temperatures over land and over the oceans, similar changes in water
temperatures near the ocean's surface, reductions in day-night temperature
differences, reduced temperatures in the stratosphere, an increase in sea
level, a general retreat of mountain glaciers, increased precipitation in
the mid to high latitudes, and more.
The global concentration of carbon dioxide is higher than at any time
in the past 160,000 years (this being known from the analysis of air bubbles
trapped in layered ice cores from Antarctica). The mean global surface temperature,
whose rise is expected to lag that of the carbon dioxide concentration,
is almost certainly higher now than at any time in the last 500 years and
quite possibly, according to evidence from Andean and Tibetan glaciers,
higher than at any time in the last 6000 years. The 10 hottest years since
1850 have all occurred since 1983, seven of them since 1990, notwithstanding
the multi-year cooling effect of particulate matter injected into the stratosphere
by a major volcanic eruption in 1991. The rates of temperature increase
expected for the next century, according to the Intergovernmental Panel
on Climate Change (IPCC), "would probably be greater than any seen
in the last 10,000 years."
Because of the long climate-response lag-time caused by the thermal inertia
of the oceans, the full climate-change impact of any given atmospheric concentration
of greenhouse gases will not be experienced until many decades after that
concentration is reached. And because a substantial part of the carbon dioxide
added to the atmosphere by human activities remains in the atmosphere for
many decades, the atmospheric concentration would decline only slowly even
if
emissions were reduced rapidly. (This is also true of a number of the other
man-made greenhouse gases.)
These two phenomena mean (1) that the planet is already irretrievably
committed to considerably more climate change than is being experienced
today and (2) that these future changes will not be able to be reversed
rapidly once they occur, even if emissions are then brought down rapidly.
3. The impact of future population and energy growth will be greater
than most people think.
All predictions are unreliable; but scenario fore-casts contingent on specified
assumptions can still be useful in helping us understand which assumptions
we should be working hardest to invalidate. "Business as usual"
(BAU) forecasts are based not on the assumption that nothing changes but
on the assumption that patterns of change remain similar to what they have
recently been ... thus, that the world rate of population growth continues
to slow at about the rate that it has recently been slowing; that the distribution
of eco-nomic growth between industrialized and developing countries continues
to be about what it has recently been (higher growth in the latter, lower
in the former); and so on.
Under BAU, the world's population, nearly 6 billion people today, is
very likely to reach 9 billion by 2050; economic activity per capita is
likely to be about 3.3 times bigger in 2050 than in 1990; and the energy
intensity of economic activity is likely to have fallen by 2050 to 60 percent
of its 1990 value. This would lead to world energy use three times larger
in 2050 than in 1990. If the carbon intensity of world energy supply continues
to fall at its BAU rate of about 0.2 percent per year, this picture would
entail world carbon dioxide emissions from the energy sector 2.7 times bigger
in 2050 than they were in 1990. Con-tinuation of BAU until 2100 would lead
to carbon dioxide emissions from the energy sector four times bigger in
that year than their 1990 value.
According to the IPCC, the carbon dioxide content of the atmosphere in
2100 under this BAU scenario would be about 715 ppmv _ two and a half times
the pre-industrial level and still rising steeply. The IPCC best estimate
of the global-average temperature increase that would have been experienced
between 1990 and 2100 in this case is 2 degrees C (3.6 degrees F), which
would make the world warmer than it has been any time in the last 125,000
years. Far from the equator (such as in the United States) the increases
would be larger. The best estimate of the sea-level rise between 1990 and
2100 in this BAU case is 50 centimeters (20 inches). Temperatures would
continue to rise for many decades after 2100 even if atmospheric carbon
dioxide concentrations were somehow stabilized at the 2100 level of 715
ppmv, and sea level would continue to rise for centuries.
If BAU were to persist until 2100, however, the CO2 concentration almost
certainly could not be stabilized near 700 ppmv and instead would rise toward
a quadrupling (1100 ppmv) of the preindustrial level, or more. The ultimate
increase in global average surface temperature associated with a quadrupling
of pre-industrial CO2 levels would probably be in the range of 7-8 degrees
C (12.6-14.4 degrees F). The eventual increase in average temperature in
the United States in this quadrupled-CO2 world would probably be in the
range of 15-20 degrees Fahrenheit.
4. Remaining scientific uncertainties are not grounds for complacency.
There are many aspects of the operation of the global climate system
and of the interaction of potential climate change with ecosystem processes
that are not yet well understood. Substantial uncertainties attend projections
of the timing of onset, magnitude, and above all regional distribution of
the physical and biological impacts of greenhouse-gas-induced climate change,
even if the future trajectories of emissions and concentrations are assumed
to be precisely known (which of course they are not). And estimates of economic
impacts are inevitably even more uncertain, given that they combine imperfect
understanding of the economic system with the imperfect understanding of
climate and ecosystem processes just acknowledged.
Many people appear to regard these uncertainties as a proper basis for
complacency _ and, more speci-fically, for delaying action to abate the
causes of climate change. But complacency and delay are unwarranted, for
three related reasons.
First, the "central" or "best" estimates of consequences
of business as usual generated in the most thorough studies by the largest
numbers of analysts (as reflected in the 1995/1996 Assessment
of the IPCC) are alarming. They entail significant and widespread damage
to health, property, and ecosystems.
Second, uncertainties cut in both directions: things might not turn out
better than the current "best" estimates, but worse, in terms
of both physical impacts and economic outcomes.
Third, the time lags built into the evolution of the problem, its diagnosis,
and the implementation
of responses (about which more will be said below) mean that waiting to
resolve all the uncertainties before taking evasive action has a high chance
of making very large damages unavoidable.
5. The time lags in implementing evasive action are longer than most
people think.
The large momentum behind population growth and growth in economic activity
per person which together tend to drive carbon dioxide emissions upward
notwithstanding efforts to improve energy efficiency and reduce carbon intensity
of energy supply has already been described. Improving energy efficiency
is a slow process because it entails replacing devices and equipment throughout
the residential, commercial, industrial, and transportation sectors, as
well as changing the behavior of billions of consumers. Reducing the carbon
intensity of energy supply is a slow process because of the large role of
fossil-fuel technologies in the current U.S. and world energy systems (85
percent of U.S. energy supply, 75 percent of the world's); the technical
difficulty and cost of modifying these systems to reduce carbon dioxide
emissions;
their long turnover times; their economic attractiveness compared to most
of the currently available alternatives; and the long times typically required
to develop new alternatives to the point of commercialization.
The goal of the Framework Con-vention on Climate Change is to stabilize greenhouse gas concentrations "at a level that prevents dangerous human interference with the climate system." There is no formal agreement yet about what constitutes a dangerous level, but most analysts who have looked carefully at the impacts side of climate change think that going beyond twice the pre-industrial CO2 concentration (about 550 ppmv) is very dangerous. Many think, in fact, that today's concentration (the full consequences of which are not yet being experienced) is dangerous. But stopping even at 550 ppmv would not be easy. It would require, in fact, that global emissions start to decline by about 2030. This would clearly require that the emissions curve in the industrialized nations start to bend away from business as usual essentially immediately.
The problem is that the world energy-economic system is a lot like a
supertanker under full power: huge momentum in the direction it is heading,
very hard to steer, very bad brakes. The science of climate change and its
impacts is telling us that the supertanker is headed for a reef; we can
tell the water is getting shallower beneath the hull, even if we can't say
exactly how far we can go before the reef rips open the tanker's bottom.
In this situation, full speed ahead is the wrong course. We need to start
slowing and steering away from the reef of unmanageable degrees of climate
change now.
6. The fates of industrialized and developing
countries are more linked than most people think. A large part of the
build-up of carbon dioxide
in the atmosphere up until now has been due to fossil-fuel combustion in
the course of the economic development of the industrialized countries.
A large part of the future growth of atmospheric carbon dioxide is expected
to come from a similar process of fossil-fueled development in the much
more populous developing countries. The joint responsibility for the problem's
creation is mirrored in the necessity for joint efforts in its solution.
The developing countries are unlikely to make the changes required for them
to develop in less carbon-intensive ways unless the industrialized countries
help with the technology and the financing.
It is clearly in the industrialized countries' interest to do so, even
if the vulnerability to the consequences of climate change may be greater
in the developing countries than in the industrialized ones. We all live
on this planet, under one atmosphere, on the shores of one global ocean,
our countries linked by immense flows of people, goods, money, information,
weapons, drugs, diseases, images, and ideas. It is simply no longer possible
for the richer countries
to expect to prosper undisturbed by the troubles of the poorer ones.
This is, among other things, a matter of U.S. national security. One
has only to think of the
probable effects of floods, droughts, rising sea level, changing disease
patterns, and declining productivity of agriculture and forestry in many
developing regions on economic adversity and impoverishment, exacerbation
of inequities within and between countries, and flows of environmental refugees.
These are likely to lead to weakening of governments, aggravation of ethnic
tensions, conflict over diminishing environmental resources, and disputes
over blame
and compensation. Some of these problems are certain to affect the national
security interests of
this country.
To put this all in the terms of the supertanker metaphor: since we are all in the same supertanker, industrialized and less developed countries together, we had better find ways to slow and steer cooperatively, starting now, rather than bickering over who is holding the wheel.