Nate Silver on How to Destroy 5% of Global GDP (and Half the World)

Today in graphics that should make your palms sweat: Nate Silver, the 538.com numbers nerd who brought the world minute-by-minute election coverage, is now delivering a detailed vision of global climate-induced dystopia.

The back story: The American Scene is home to an ongoing debate over the costs and benefits of Waxman-Markey, the climate change bill that recently passed in the House and is now headed for the Senate. In arguing against it, commentator Jim Manzi points to the Intergovernmental Panel on Climate Change estimate that warming would decrease global GDP by 5 percent, saying that's pretty marginal compared to the economic impact of the proposed legislation. But a good portion of the world's countries register mere blips on counts of total global GDP, even though they account for much of its population. How much, exactly? Into the fray jumps Mr. Silver and his map:

I'm not sure how or why Somalia survives the cut, but that's just quibbling. The point is clear, and it's pretty devastating: a 5 percent swing in global GDP may not seem like much, but GDP might not be the best metric to use when wiping half the planet off the map would barely affect it. But then add in how unpredictable economic shifts are and how many non-economic benefits would come along with the legislation, and an argument over the impact of a 5 percent difference in GDP becomes kind of ridiculous. And that's ultimately the takeaway: even the best GDP modeling won't get past the tip of the iceberg on this one.