Heed This Warning

Thursday, September 28, 2006

BENEATH ITS dry scientific lingo, a new analysis of global climate change by a group of NASA scientists is terrifying. Headed by climate specialist James E. Hansen, the group argues that recent global warming has been quite rapid -- about 0.2 degrees Celsius over each of the past three decades -- and has largely tracked climate models that predict more dramatic warming in the decades to come. If the world continues increasing carbon emissions at its current pace, by about 2 percent a year, the authors argue that the resulting warming will cause the extinction of about 60 percent of species around the world and "sea level rise of several meters per century with eventual rise of tens of meters, enough to transform global coastlines."

The scientists posit an alternative scenario as well, one predicated on dramatic reductions of carbon emissions. In that case, sea levels would still rise substantially and "cause problems for humanity," and 20 percent of species would still go extinct -- but the most catastrophic effects of warming might be averted. Most distressingly, they contend that humanity doesn't have long to make up its mind whether to pursue policy changes; another decade without emissions being reduced, they said, would probably make the alternative scenario infeasible.

The likely consequences of global warming are a hotly debated subject, and one has to be cautious about predictions concerning hugely complicated systems -- such as average global temperature over time. But there is at least a decent chance that this and the many similar analyses by other reputable climatologists will prove correct. And that means that global warming represents a policy crisis responsible politicians can no longer ignore -- one as potentially existential as the threat of global terrorism, only in slow motion.

Countering that threat will require regulatory initiatives and societal investments. It will require significant changes in American attitudes toward energy use and conservation. But these may prove far less wrenching than many people imagine. What it certainly also will require is a great deal of political will -- political will of precisely the type the Bush administration has dedicated to a host of other issues but has assiduously avoided devoting to climate change. Most of all, it will require an end to denial -- denial that the problem exists, denial that anything can be done about it if it does and denial that the problem is urgent and requires immediate attention.

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