Hi Tundra,

For once I think you are wrong. Albedo changes do have a significant effect and are typically considered one of the feedbacks causing the the onsets and ends of ice ages. The authors used standard GCM's to predict the size of the impacts. Now, if I'm reading the second to last paragraph correctly, the authors predict that the C02 radiative forcing would outweigh the albedo effects for about 80 years (after which enough C02 is drawn into the deep oceans and rocks). The Guardian write up didn't make that clear. Surprise!

The other issue is that it is not a comparison of converting between forest and grassland but of the difference between the two initial conditions. Current agricultural practices, mainly tilling, release about half of the carbon stored in the soil. So, as you know, converting to agricultural use incurs a large carbon debt.