Decrease in the summer rainfall of the southern United States coast and the Caribbean due to climate change

摘要

Simulations from the North American Regional Climate Change Assessment Program(NARCAPP) Geophysical Fluid Dynamics Laboratory (GFDL) AM2.1 timeslice experiment, forcurrent climate (1971-2000) and future climate (2041-2070), were compared and contrasted toassess how May through October accumulated rainfall is responding to climate change along thesouthern United States coast and in the Caribbean under the Intergovernmental Panel on ClimateChange (IPCC) A2 emissions scenario (a scenario of relatively high emissions increase). Thesimulations were done on a global domain at a horizontal resolution of roughly 50 km.There is an overall decrease of about 200 mm (30 percent) in the May through Octoberrainfall in the region of the southern United States coast and the Caribbean. The absolutedecrease is larger in the regions that receive the most rain. However, proportionally, the decreaseis larger in the regions that receive the least rain. For the subregion of Florida, rainfall time seriesindicate a delay of the region?s late wet period in the future climate. This shift needs to be furtherexamined to determine its significance and underlying physical processes. Florida also receivedless rainfall in future climate, but the standard deviation of the early and late wet periods wasfound to be larger. This is in accord with the findings of the IPCC of an increase in globalextremes as a result of climate change. In a future study, the time series for four other subregionswill be analyzed.