NewsBREAKTHROUGH OF THE YEAR

Global Warming, Hotter Than Ever

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Science  21 Dec 2007:
Vol. 318, Issue 5858, pp. 1846-1847
DOI: 10.1126/science.318.5858.1846

Climate change, a perennial runner-up for Breakthrough of the Year, broke from the pack this year--both in the pages of this section and in the public arena.

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Climate change, a perennial runner-up for Breakthrough of the Year, broke from the pack this year—both in the pages of this section and in the public arena.

In 2007, the debate about the reality of global warming ended, at least in the political and public realms in the United States. After 6 years of silence, the United Nations' Intergovernmental Panel on Climate Change (IPCC) drew heavy and wholly positive media coverage for a series of wide-ranging reports. The world is warming, IPCC declared; human activity is behind most of it, and if it keeps up we'll pay a price. But the panel also said that much of the climate pain might be avoided if the world agrees to begin sharing the economic pain. Impressed with that performance, the Nobel committee anointed IPCC, as well as climate campaigner Al Gore, with its Peace Prize.

Other reminders also drove home the gravity of the climate change situation. Scientists now worry that the record melt-back of sea ice during the summer might indicate that feedbacks are amplifying the effects of global warming. A steady stream of media reports this year noted record melting of Greenland ice, record-high temperatures in the United States, and surging Antarctic glaciers. And the energy crisis deepened as oil prices increased to $100 a barrel, boosting anxieties about the future of fossil fuels.

Politicians weren't idle, although U.S. climate policymakers still have little to show for their concern. Since gaining control of Congress in January, Democrats have transformed the debate from “if to when for mandatory limits on U.S. emissions,” says Paul Bledsoe of the National Commission on Energy Policy in Washington, D.C. But hundreds of hearings and reams of legislative proposals have not translated into legislation.

The status of the most prominent Senate proposal, offered by senators Joseph Lieberman (I-CT) and John Warner (R-VA), illustrates the pitfalls that lie ahead for Democrats. Introduced in October after months of negotiations with corporate lobbyists and environmental groups, the bill would cut U.S. emissions by roughly 15% of 2005 levels by 2020 with innovative proposals for emissions credits to spur new technologies. But the debate at a 5 December markup exposed some of the hurdles that the legislation will face in what experts expect will be a multiyear slog. Democrats from Midwestern and coal states, for example, helped kill a proposed measure that would have given the Environmental Protection Agency the ability to tighten the caps if scientists determined that warming was going to be more than 2°C above the preindustrial average. Meanwhile, the House is even further behind on emissions limits. As Science went to press, Congress was poised to pass a landmark automobile fuel law that, if it survives a threatened White House veto, will require 35 miles per gallon (14.9 kilometers per liter, or 6.7 liters per 100 kilometers) efficiency by 2020.

Dwindling.

Dal Lake in Kashmir, India, has shrunk to half its former area over 4 decades—one of many possible early casualties of worldwide climate change.

CREDIT: ALTAF QADRI/EPA/CORBIS

Elsewhere, there have been mixed signs of progress. At press time, in Bali, Indonesia, negotiators from Europe and the developing world were striving to persuade the United States to consider binding cuts for the 2012 follow-on to the Kyoto treaty. China has warmed slightly to carbon limits—if the deadline is far enough away. Meanwhile, growing numbers of prominent climate experts are calling for research into geoengineering, the deliberate tinkering with Earth's climate to reverse warming. Given the slow political progress, says atmospheric scientist David Battisti of the University of Washington, Seattle, “we might need a plan B.”

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