This year’s battle over climate legislation has begun in the US Congress, with the introduction today of draft legislation to control greenhouse gases through a cap-and-trade system.

The bill, introduced by Henry Waxman (Democrat, California) and Edward Markey (Democrat, Massachusetts) in the House of Representatives, would among other things cut greenhouse emissions 20 percent from 2005 levels by 2020. That’s more ambitious than President Barack Obama’s stated goal of a 14 percent cut — though both bills would target an 80 percent cut by 2050. (New York Times)

It’s the first entry in what could be several competing bills to set up cap-and-trade systems prior to international climate negotiations in Copenhagen this December (Nature).