USE OF GENERAL-CIRCULATION MODEL OUTPUT IN THE CREATION OF CLIMATE-CHANGE SCENARIOS FOR IMPACT ANALYSIS .1.

Many scientific studies warn of a rapid global climate change during t he next century. These changes are understood with much less certainty on a regional scale than on a global scale, but effects on ecosystems and society will occur at local and regional scales. Consequently, in order to study the true impacts of climate change, regional scenarios of future climate are needed. One of the most important sources of in formation for creating scenarios is the output from general circulatio n models (GCMs) of the climate system. However, current state-of-the-a rt GCMs are unable to simulate accurately even the current seasonal cy cle of climate on a regional basis. Thus the simple technique of addin g the difference between 2 x CO2 and 1 x CO2 GCM simulations to curren t climatic time series cannot produce scenarios with appropriate spati al and temporal details without corrections for model deficiencies. In this study a technique is developed to allow the information from GCM simulations to be used, while accommodating for the deficiencies. GCM output is combined with knowledge of the regional climate to produce scenarios of the equilibrium climate response to a doubling of the atm ospheric CO2 concentration for three case study regions, China, Sub-Sa haran Africa and Venezuela, for use in biological effects models. By c ombining the general climate change calculated with several GCMs with the observed patterns of interannual climate variability, reasonable s cenarios of temperature and precipitation variations can be created. G eneralizations of this procedure to other regions of the world are dis cussed.