| Abstract |
General Circulation Models (GCMs) have projected global warming of from 3 to 8 degrees F to take place over a period of from 50 to 100 years. The Forest Service Southern Global Change Program (SGCP) has proposed the use of GCM output as input to forest assessment models to estimate the potential impacts of climate changes on forests of the South and Southeastern U.S. The report reviews, organizes, summarizes and makes recommendations concerning the use of four climate model projections in forest assessments. Some primary sources of inter-model variability include model version (age), numerical solution technique, time and space resolution and parameterization schemes. Model version generally impacts the time and space resolution and choice of parameterization schemes. Magnitude of change varies widely, but the four GCMs examined here all project warmer air temperatures and higher humidities throughout the year, decreasing cloud cover during the Fall, Winter and Spring seasons and increasing summertime precipitation for the South and Southeastern U.S. Although some consensus among models over large geographic regions can be identified, there is, as yet, no established means of determining the confidence that can be placed in these outlooks. GCM output should be combined with historical case studies, empirical and semi-empirically constructed climate scenarios to provide a range of possible climatological futures. |
