1 February 2005International Herald Tribune
Under the first treaty addressing global warming, 193 countries, including the United States, pledged to avoid "dangerous" human interference with the climate.There was one small problem: No one defined dangerous. With no clear goal, smokestack and tailpipe emissions of heat-trapping gases linked to rising temperatures climbed relentlessly.On Feb. 16, the Kyoto Protocol enters into force, requiring participating industrialized countries to cut such emissions. But its targets and timetable were negotiated in the absence of any agreement on what amount of reductions would foster climatic stability. The arbitrary terms were cited by President George W. Bush when he rejected the Kyoto pact in 2001.Now, some scientists and policy makers are trying to agree on how much warming is too much. One possible step toward clarity comes Tuesday, when 200 experts from around the world meet in Exeter, England, at the invitation of Prime Minister Tony Blair, for three days of talks on defining "dangerous climate change" and how to avoid it.The veteran American climate researcher running the meeting, Dennis Tirpak, formerly of the Environmental Protection Agency, said that experts in the field always realized it would take a long time for science's projections to be absorbed by society, but few thought it would take this long."I've always been a believer that science and truth will win out in the end," he said. "But I have a sense we might be running out of time."It has taken this long not just because the "dangerous" question is complicated, but also because it itself contains dangers. If scientists offer answers, they can be criticized for playing down uncertainties and intruding into the policy arena. If a politician answers, that creates a yardstick for measuring later progress or failure. It is much easier for everyone simply to call for more research.But some experts now say it is becoming clear that by the time clear evidence is at hand, calamity later in the century will be unavoidable. They say fresh findings show that potentially enormous environmental changes lie ahead."I think that the scientific evidence now warrants a new sense of urgency," said James Hansen, a climate scientist and director of NASA's Goddard Institute for Space Studies.A particular concern is the Arctic. An eight-nation, four-year study concluded in November that accumulating carbon dioxide and other emissions from human activities were contributing to the thawing of tundra and the retreat of sea ice.Recent studies of accelerating flows of ice to the sea in some parts of Antarctica also point to the prospect of a quickening rise in sea levels in a warming world. Other scientists point to the prospect of intensified droughts and floods.With pressure building for fresh action, some countries and groups of experts have tried to define a specific rise in Earth's average temperature that presents unacceptable risks.The European Union has set this threshold at 2.5 degrees Celsius, or 4.5 degrees Fahrenheit, of additional warming from current conditions. That was also the danger level chosen last week by an international task force of scientists, policy experts, business leaders and elected officials led by Senator Olympia Snowe, Republican of Maine, and Stephen Byers, a Labour Party member of the U.K. Parliament.Some scientists have criticized this approach, saying understanding of the impact of greenhouse gases on the atmosphere remains far too primitive to manage emissions and thus avoid a particular temperature target.Others say the most logical response is to make societies more resilient to inherent extremes of climate. "If we just significantly minimize our vulnerabilities to the extremes which occurred during the last 250 years, we'll be O.K. for the next 100," said John Christy, a climate scientist at the University of Alabama who has long opposed cuts in emissions. As for rising seas, he said, "You've got 100 years to move inland."Michael Schlesinger, who directs climate research at the University of Illinois, will contend at the Exeter meeting that the persistent uncertainty about big climate perils is precisely the reason to invest now in modest mandatory curbs on greenhouse-gas emissions.Only with such a prod will societies move toward less-polluting choices, even as research continues on energy options that could in a few decades sharply reduce the human contribution to the greenhouse effect. Investors use the same hedging tactic when financial markets are fluky, shifting money from riskier stocks to safer investments.Without global participation in such emission curbs, though, the shared atmosphere will essentially remain a dump with no gate or tipping fee for countries rejecting action.Any consensus on climate risks is likely to intensify pressure on the Bush administration to shift from its current opposition to any cuts in the gases. The president has pushed for additional research on climate change and energy technologies that could take a decade or two to develop.Last week, in Davos, Switzerland, Blair pressed the United States to join Britain and other major industrialized countries that have committed to mandatory curbs on the gases, which come mainly from burning coal and oil.While the risks remained uncertain, Blair said, "It would be wrong to say that the evidence of danger is not clearly and persuasively advocated by a very large number of entirely independent and compelling voices."The Exeter meeting is likely to set the tone for the next review of climate trends and causes by the Intergovernmental Panel on Climate Change, a scientific body under United Nations auspices that is the closest thing there is to a gauge of human understanding of the issue. It will be issued in 2007.In an interview, Rajendra Pachauri, chairman of that body, said it was clear that emissions contributing to warming had to be reduced, but defining what was dangerous remained a "value judgment" by society and its elected officials."You can reduce uncertainties and therefore create the force of scientific evidence that might propel action," Pachauri said. "But I'm afraid there will never be that sort of silver bullet that tells you this is it."
