Revkin again claims to see "plenty of signs" that CO2 is overheating the planet, but forgets to tell us specifically how he distinguishes natural warming from human-induced warming

Dot Shot: Hudson River Locked in Ice on March 18 (2007) - NYTimes.com

There are plenty of signs — amid the variability in conditions year to year, decade to decade, region to region — of the heating influence of greenhouse gases.

But variability, both over time and geography, is important to keep in mind. For instance, while many have pointed to the extraordinarily temperate conditions in the contiguous United States this winter, they were matched by the extraordinarily intemperate, and deadly cold, conditions in many parts of Europe, Alaska and elsewhere.

The resulting complexity doesn’t bode well for those seeking urgent action to get the carbon [dioxide] out of the growing global energy system.