A significant fraction of future rainfall change in the tropics will occur independently of surface warming, reports a paper published online in Nature Geoscience this week. The findings suggest that geoengineering schemes aimed at reducing global warming without removing carbon dioxide from the atmosphere would fail to fully mitigate rainfall change in the tropics.
Sandrine Bony and colleagues used climate model simulations to assess the impact of an unmitigated rise in atmospheric carbon dioxide concentrations on rainfall and atmospheric circulation in the tropics over the twenty-first century. They find that much of the regional rainfall change was unrelated to surface warming. Instead, a shift in atmospheric vertical motions, induced by a rise in carbon dioxide concentrations, was responsible for much of the change in tropical rainfall.