Decisive action needed as warming predictions worsen, says expert

EurekAlert: Greenhouse gases in the atmosphere are rising more rapidly than expected, increasing the danger that without aggressive action to reduce emissions the climate system could cross a critical threshold by the end of the century, warns a leading member of the Nobel Prize-winning Intergovernmental Panel on Climate Change. Studies indicate that greenhouse warming could trigger a vicious cycle of feedback, in which carbon dioxide released from thawing tundra and increasingly fire-prone forests drives global temperatures even higher.

Chris Field, director of the Carnegie Institution's Department of Global Ecology and co-chair of the IPCC Working Group 2, will address these issues at a symposium titled "What Is New and Surprising since the IPCC Fourth Assessment?" at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago.

…"The data now show that greenhouse gas emissions are accelerating much faster than we thought," says Field. "Over the last decade developing countries such as China and India have increased their electric power generation by burning more coal. Economies in the developing world are becoming more, not less carbon-intensive. We are definitely in unexplored terrain with the trajectory of climate change, in the region with forcing, and very likely impacts, much worse than predicted in the fourth assessment."

New studies are also revealing potentially dangerous feedbacks in the climate system that could convert current carbon sinks into carbon sources. Field points to tropical forests as a prime example. Vast amounts of carbon are stored in the vegetation of moist tropical forests, which are resistant to wildfires because of their wetness. But warming temperatures and shifting rainfall patterns threaten to dry the forests, making them less fireproof.

….Warming in the Arctic is expected to speed up the decay of plant matter that has been in cold storage in permafrost for thousands of years. …"The IPCC fourth assessment didn't consider either the tundra-thawing or tropical forest feedbacks in detail because they weren't yet well understood," he says. "But new studies are now available, so we should be able to assess a wider range of factors and possible climate outcomes. One thing that seems to be certain, however, is that as a society we are facing a climate crisis that is larger and harder to deal with than any of us thought. The sooner we take decisive action, the better our chances are of leaving a sustainable world to future generations."….

Tundra, in Alaska's Arctic National Wildlife Refuge