So Climate Change Is Real, Now What?

If the study of climate change were a Hollywood movie, it would have ended almost two years ago. The leaders of an epic struggle to prove humans are warming the planet accomplish their mission and win a Nobel Peace Prize. Cue up triumphant brass, cut to credits, fade to black.

Alas, the Nobel-winning 2007 Fourth Assessment Report from the Intergovernmental Panel on Climate Change, which synthesized years of global scientific effort, simply offered another in a string of summaries dating to 1990. There will be a fifth, perhaps in 2012.

The report focused the field: Many efforts underway today aim to explain the uncertainties the Fourth Assessment identified in climate mechanisms and impact.

But scientists now see a need for a new storyline. The science is settled, these experts say. The field must accept change as a given and focus instead on adaptation and mitigation.

The climate community, in other words, must emerge from field and lab to point the way out of this mess.

"Physical science is still very important, but for many people -- and for some physical scientists -- we already know enough," said Linda Mearns, a senior scientist at the National Center for Atmospheric Research’s Institute for the Study of Society and Environment.

Success in both discovery-based science and a more policy-oriented science will be crucial if the IPCC – the world authority on climate change – hopes to fulfill its promise of translating scientific results into meaningful action, said Rajendra K Pachauri, the IPCC chairman.

"We need to inform, but we also need to stimulate the audience to think and act and emphasize existing solutions," he said. "We need to start looking at the social science aspects.... You really need to mobilize the community. I really don’t think we’ve done enough."

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Work on climate-change adaptation and mitigation is nothing new. The IPCC’s 2007 report devoted hundreds of pages to these topics. But Lisa Dilling, a professor at the University of Colorado’s Center for Science and Technology Policy Research, says scientists themselves must adapt if their work is to make a real-world difference.

Traditionally, basic science "is not really connected to society," Dilling said. Scientists "put it out there and hope it’s relevant. There’s some push out there to make science more useful, but I don’t think the bulk of climate science has gone that way yet."

First, the science: Our understanding of the Earth and its responses to rising global temperatures is far from complete.

Several influential researchers – Stanford University climatologist Steve Schneider, National Center for Atmospheric Research director Eric Barron, Journal of Climate editor Andrew Weaver, and Carnegie Institution scientist Christopher Field -- point to key gaps hindering a full grasp of climate change’s consequences. 

These, they agree, must be addressed for the science to be truly useful to policymakers and the general public:

• Melting ice. IPCC predictions of sea-level rise account only for thermal expansion of the warming oceans. What happens when glaciers and large ice sheets in Greenland and Antarctica melt? The models don’t say, because the mechanisms aren’t fully understood. But it’s sure to be more than the 0.6-meter worst-case scenario of the most recent IPCC forecast.
• The carbon cycle. Climate models still can’t account for how carbon and other greenhouse-gas constituents cycle between trapping heat in the atmosphere to being trapped in trees, soils and stones.
• Better resolution. Global climate models can "see" only in crude blocks hundreds of kilometers across -- scarcely enough to resolve the Rocky Mountains or Africa’s Sahel.
• Tipping points. Scientists -- to society’s peril -- don’t know what triggers irreversible changes such as deglaciation, sea-level rise and extinctions.
• "Next-door" fields. Climate research needs to broaden its reach into other fields -- public health, invasive species, crop science — that will feel the consequences of a disrupted climate.