I only had a few minutes last week to blog at work about a new paper on climate feedbacks by Chris Jones at the UK's Met Office, but I finally had some time this afternoon to sit down and read it more carefully. Here's more....

(climate wonks click through)

Jones and Peter Cox looked at the anomalous rise in CO2 in 2003, which they concluded couldn't be blamed on the usual: El Niño.

When you get an El Niño, you get tropics that are, on balance, drier and warmer. That means more CO2 in the air. The opposite occurs in La Niña years. Carbon dioxide is steadily rising, but it's not a flat line, and the biggest source of variability, according to Jones and Cox, is the El Niño cycle. Add in the effect of volcanic activity, and you can explain most of the variability seen seen in CO2 numbers since folks began collecting data in the late 1950s.

But 2003 (and, to a lesser extent, 2002) was just weird. The huge increase in CO2 couldn't be explained with the El Niño numbers. But remember that 2003 was extraordinarily warm in Europe and Asia, and Jones and Cox cite research linking the heat wave to large-scale burning in Siberia. And with the heat wave of 2003 linked to global warming, it's not unreasonable to chain them all together: greenhouse warming->fires->more CO2->more warming. To quote Jones and Cox:

If the anomalous 2003 rise in CO2 was due to the hot conditions of that year which in turn may have been due to man-made global warming then might we be seeing the first signs of this positive feedback?