December 6, 2009 . Climate change could be 1 1/2 times worse than previously anticipated The long term warming will likely be about 50% greater than thought. A new study that looks at climate sensitivity three million years ago when CO2 was thought to be in equilibrium across the planet, polar ice was significantly reduced, sea level higher etc.
The long term ramifications of man-caused climate change have really not been looked at in much detail until now. Those studies that did, used the more familiar short term techniques extended into the future. These techniques poorly recreate the slow feedback processes. These slow feedback processes are difficult to model, at least until now. New modeling techniques are what this paper is all about. The new study takes a different approach and comes up with about half again as much warming as earlier thought.
So what are the differences between fast and slow feedback processes? Fast feedback processes, are those that are used in all climate models. CO2 and other greenhouse gases are only responsible for a fraction of the warming. It’s the feedback processes that really heat us up. The water vapor feedback alone is estimated to be twice that from just greenhouse gases. A little warming causes more evaporation, which captures more infrared radiation causing more warming and more evaporation, etc. Other "fast" feedback processes are the cloud process, albedo from ice and snow and aerosols. Slow feedbacks take a er, long time to happen. Vegetation changes and ice sheet changes, soil carbon changes from desertification or aforestation are all slow feedback processes. When a forest grows up in a tundra ecosystem because of a warming climate, it takes a while. The forest soaks up more heat because winter snows can not easily cover every single bit of vegetation like can happen with a tundra plain. The extra heat then combines with factors from the albedo feedback to compound warming and the vegetation and albedo feedback processes.
What does this mean for me and you? The authors of the paper are not saying, but it will not just automatically get 50% hotter when our climate catches up to the atmospheric CO2 concentration. The extra warming starts now.
Nature Geoscience Sequestration Special http://www.nature.com/ngeo/journal/v2/n12/index.html