The oceans are the world's heat sink... so energy that is absorbed by the ocean doesn't and won't be quickly radiated back into space. A warming ocean is clearly a major issue with regard to global climate change, especially with respect to ice sheet melt rates... but it also has a huge effect on the trade winds, which affect all global weather patterns.

On land, however, I am not the least bit concerned whether a few million square miles of central Asia have a 1 degree average difference or not (this would largely be a result of a warmer winter and night, offsetting a cooler day and summer... with the major annual difference being a lessoning of snow cover for however long the area would normally see snow). Add to this the fact that the big boogeyman for global warming - with respect to the continental interiors, is desertification... something that forests specifically help protect the land from.

My response to Xando was only regarding Albedo changes on land, not overall. Over water, a wonderful thermal storage medium, that's a completely different issue. However, I don't know of any forests grown over the seas, so I didn't think that was a necessary caveat.

:)

You're right, of course, about the agricultural issues. That carbon debt is FAR FAR FAR larger when converting an existing forest into agriculture, because of the thousands of tons/acre of CO2 that are sequestered as trees.

But the authors of the study weren't advocating burning forests down in order to make more farmland... they were just trying to prevent reforestation efforts from recieving carbon offset money. I disagree with them quite vehemently... but I am the first to mock people when they assert that the world could be saved through the planting of the magic forests (we'd need most of land area of the world to be planted)... but I do strongly believe that reforestation would have some cost-efficient mitigation effects. It's just limited in the potential scope to a few percent of the problem.