Climate Change 2001:Third Assessment Report
Impacts, Adaptation, and Vulnerability, by Working Group II.
Mitigation, by Working Group III.
(“Summaries for Policymakers” available on line at www.ipcc.ch)
National Energy Policy: Report of the National Energy Policy Development Group
The two documents listed here, each issued since the first of the year, offer competing blueprints for the twenty-first century. They are diametrically opposed in their implications; paying heed to one would mean ignoring the other. Since they concern the greatest threat to Earth’s physical stability in human history—the warming of our planet caused by the consumption of fossil fuels—the choice between them carries unusual significance. In fact, it would not be hyperbole to say they outline the first great choice of the new millennium, a choice that may well affect the planet throughout the thousand years to come.
The report of the Intergovernmental Panel on Climate Change consists of three large volumes that were put into final form at conferences held in Shanghai, Geneva, and Accra during this past winter.1 They distill millions of man-hours of work on the future of the climate into a readable and understandable summation that argues, in a measured but urgent scientific tone, that we stand on the edge of cataclysm.
To understand where these volumes come from, we have to go back to the 1980s, when the theory of global warming was first widely put forward in this country, most notably by the NASA scientist James Hansen. His computer model indicated that as human beings continued to burn natural gas, coal, and oil, the carbon dioxide produced as a byproduct and accumulating in the atmosphere was beginning to perceptibly heat the earth, and that this heating would rapidly accelerate. The molecular structure of carbon dioxide, and of a number of other, rarer, industrial gases, prevent the sun’s radiation from reflecting off the earth, trapping heat and thereby increasing global temperature—the “greenhouse effect.” At the time, it was a theory with plenty of doubters.2 Though there was some public pressure for immediate action, especially following an extremely hot summer across the North American continent in 1988, national governments instead funneled many millions of dollars into research on the topic. And so the scientists searched for answers in the upper atmosphere and under the sea, on tundra and desert, permafrost and icecap, in tree rings and glacial ice cores, in pollen sediments and bird-nesting records, with satellites and weather balloons. They made their computer models more and more accurate, testing them by looking at past climate or tracking the chemicals released by the 1991 eruption of Mount Pinatubo in the Philippines. And they began to synthesize all this research into workable summary form for the policymakers who, it was assumed, would deal with the results.
The IPCC, organized under UN auspices, is the formal vehicle for that process of summation, and a look at its methods should dispel any doubt that this is still shaky science. At five-year intervals, about one hundred member governments propose the names of their best climate scientists. From the thousands of nominations, the scientific leadership of the IPCC then picks several hundred for each of three working groups, based on their publications in scientific journals, and each scientist is assigned responsibility for synthesizing all the peer-reviewed literature on a particular aspect of the problem. More scientists are drafted as reviewers and critics—by the end of this five-year cycle, at least 1,500 experts, including nearly every im-portant climatologist on earth, were somehow involved in the process.
The working group reports are then reviewed by scientists again selected by member nations, condensed into hundred-page technical summaries, further condensed into twenty-page summaries for policymakers, and then reviewed one more time in a plenary session where representatives from all governments go over the final document line by line. This process of consensus is not only slow—it also tends to mute the outcome even further. At the Working Group II conference in Geneva in February, for instance, the delegates from the Saudi government, which has a big stake in downplaying global warming, offered an almost continuous stream of objections and amendments—by the end, however, the final document was unanimously approved.
The first breakthrough from this exacting process came in 1995, during the second assessment period, when the final summation yielded the conclusion that “the balance of evidence suggests a discernible human influence on global climate.” Though couched in the quiet language of science, this was the first official recognition that human beings had become numerous enough, and industrialized enough, as a species to produce emissions that would radically alter the most fundamental force of the planet’s surface. In the five years since, leading up to this year’s so-called Third Assessment Report, or TAR, more researchers with more literature to assess and synthesize have reached more assured and nuanced conclusions; in general they have pulled the questions of climate science further out of the murk of doubt and into a broad consensus.
Working Group I, charged with assessing the current understanding of climate science and making predictions for the century to come, concluded this time around that “there is new and stronger evidence that most of the warming observed over the last fifty years is attributable to human activities.” The members of the group further predicted, using six different projections about how large economies would grow and how fast they would make the transition to non-carbon sources of energy, that the global average temperature would increase by 3 to 11 degrees Fahrenheit in this century, a forecast significantly bleaker than their 2 to 6 degree estimate of five years ago. If it comes true, the earth will be transformed into a planet unlike any human beings have ever known. Global average temperature, currently 59 degrees, would likely rise to the mid-60s, perhaps as high as 70 degrees. A 70-degree afternoon may be delightful, but a 70-degree planet, or even a 65-degree one, would be unlike anything we’ve ever encountered. It would mean a vast increase in the amount of energy trapped in the narrow envelope of our atmosphere, energy that would increase the rate of almost every natural process save for the volcanic and the tectonic.
Working Group II, assigned to assess the scale of those effects, predicts that even the more moderate temperature increases will lead to reductions in crop yields in most tropical and sub-tropical regions where food is scarce. (Yields may actually grow initially in temperate regions, and then start to shrink as the temperature increase rises more than a few degrees.) They also forecast decreased availability of water in arid regions as well as much higher risk of flood from heavier rainfall. (The reason for this paradoxical effect is that warm air holds more water vapor than cold, and hence both evaporation in dry areas and deluge in wet ones increase.) Rising sea levels, they say, could also flood many low-lying areas and eventually submerge some island and delta nations.
They also predict that because a warmer and wetter world will favor mosquitoes, more people will be exposed to malaria and dengue. In addition, they warn of potentially nasty surprises, including perhaps the “significant slowing” of the Gulf Stream that warms the North Atlantic, which would have the effect of chilling Western Europe. The poorest parts of the world, they conclude, “have the least capacity to adapt and are the most vulnerable.” Eventually the whole world will be affected, but in the short term the US is likely to be luckier than almost any other region. That our continent is large, relatively isolated, and in a mid-range latitude will slow many damaging effects; and that, as we shall see, has major political implications.
Finally, Working Group III, which looked at strategies for slowing the flow of carbon dioxide and other greenhouse gases into the atmosphere, examined a daunting series of computer models that tried to forecast the future of economic growth and technological change. They acknowledge that programs for sequestering carbon dioxide by, say, growing trees that would absorb it could yield some useful results. But they also concluded that all strategies for mitigating greenhouse gases and stabilizing their concentration “are characterized by the introduction of efficient technologies for both energy use and supply, and of low or no-carbon energy.” In addition, while they acknowledge that moving quickly to, say, retire existing power plants would raise the cost of this effort, they also add that “rapid near-term action would decrease environment and human risks.”
At the moment, any such talk is purely conjectural, of course. The one international attempt to agree on even modest CO2 reductions, the Kyoto accords, has now foundered, and in the US, despite pledges by leaders of both parties to stabilize emissions, we continue to burn more and more fossil fuel. Because the momentum toward greater fossil fuel use is so strong, especially in developing countries, CO2 levels will inevitably rise for many years to come—indeed, many policymakers now despair of stopping their rise short of the 560 parts per million that would represent a doubling of the concentrations before the Industrial Revolution.
Despite those hard truths, the IPCC report is still a turning point. Boiled down, its thousands of pages, graphs, and models say that the problem of global warming is dire, and addressing it requires the conversion of our economies from fossil fuels to some other base. It doesn’t say exactly how much less CO2 we should produce. (The common shorthand estimate used by climatologists for the last half-decade is that 60 to 80 percent reduction in current levels of CO2 emissions would suffice to stabilize climatic disruption at its current level.) Nor does it say exactly when this must be done—the IPCC considers policy prescriptions outside its province. But there can be no doubt from the tone and argument of the documents that the answer to those questions is: as much as possible, and as soon as possible.
Each working group is much bolder in its statements than in the past, mostly, I think, because the planet itself, beginning around 1995, seemed to start conducting its own peer review of conclusions about global warming. Averaged globally, record hot years came one after another, and with them came evidence of truly dramatic change, precisely the sort of changes that confirm the validity of the accepted scientific models. Indeed, though the world has so far warmed only about one degree Fahrenheit, which is to say perhaps a quarter or a fifth of what we can expect in the century to come, the results, as listed in the new IPCC documents, are already frighteningly large. Temperature does seem to have effects on almost everything that happens on the surface of the planet (tectonic and volcanic activity may be the only completely “natural” forces left). For instance:
? Arctic sea ice is melting at a rapid pace—it is 40 percent thinner than it was forty years ago. (This will not raise the sea level by itself for the same reason that melting an ice cube in a drink doesn’t raise the level of liquid in a glass. The projected rise in sea level of at least a foot would result mostly from the thermal expansion of hotter water.)
The reports will be published in full by Cambridge University Press in August. A fourth volume, Climate Change 2001: Synthesis Report, will be published in October 2001.↩