March and April warmest ever. Humans must adapt, report says.

Experience dealing with floods, heat waves, and droughts gives US decisionmakers many options to consider, says Thomas Wilbanks, who heads the global change and developing countries program at the Oak Ridge National Laboratory in Oak Ridge, Tenn. One challenge: "If climate change takes us beyond the envelope of historical experience, the options we know about now may not be adequate," says Dr. Wilbanks, who led the team producing the NRC volume on adaptation.

Clinging to "known options" could lead to what he calls mal-adaptation. For instance, he says, the current definition of the expanse of flood plains along rivers inundated in a once-in-a-100-year flood "is way behind recent evidence about flooding dangers." The federal government is using the latest technology to develop more accurate elevation maps along rivers. But the frequency and intensity of flooding appears to be changing as well in some areas, and researchers say it's unclear the latest hydrology information is being folded into the new flood-hazard maps.

Depending on location, communities can begin to take simple steps, which start with figuring out what sort of vulnerabilities they may face under a range of global warming scenarios, Wilbanks says. Some of these can be offset by what he calls incremental steps.

Incremental steps clearly won't work in other situations, he adds, citing the Gulf Coast as an example. Federal estimates suggest that by 2050, sea level rise along stretches of the Gulf Coast could range from two to four feet, a figure that includes the effects of natural and human-triggered subsidence.

Over the short term, he says, it may be possible to make due with seawalls, hardening structures to withstand coastal flooding from storms, and other approaches. "But the longer-term response may need to consider some movement of infrastructure and even human settlements away from vulnerable areas," he says.

"Clearly, where more-severe climate-change impacts are a possibility, we need to start some serious contingency planning soon," as well as boost research on the implications of those effects and approaches to dealing with them, Wilbanks says.

Adaptation doesn't need a federal response, "it needs a national response," he says – one that involves virtually every segment of the public and its political institutions.

One step in that direction is scheduled to take place next week in Washington – the nation's first climate-adaptation summit. It's been organized by UCAR and the White House Office of Science and Technology Policy. The two-day meeting will bring together those who do the research with those interested in using the results of the research in adaptation planning, UCAR's Fellows says.

"In many respects, the states are out in front of the federal government," he says. It's time to bring all those voices in and say: 'Federal government, here's how you can help us.' "

Related:

• At Copenhagen, alarms on ocean acidification
• Adapting to climate change depends on site-specific knowledge
• Blog: Climate change could redraw national borders

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