SIMULATED FUTURE SEA-LEVEL RISE DUE TO GLACIER MELT BASED ON REGIONALLY AND SEASONALLY RESOLVED TEMPERATURE-CHANGES

Climate change is expected over the next century as a result of anthro pogenic emissions of greenhouse gases and aerosols into the atmosphere , and global average sea level will consequently rise. Estimates' indi cate that by 2100 sea level will be about 500 mm higher than today as a result of global warming, with thermal expansion of sea water accoun ting for over half of this rise. The melting of glaciers and ice sheet s will contribute much of the remainder. We present an improved calcul ation of glacier melt, which uses the temperature patterns generated b y a coupled atmosphere-ocean general circulation model(2,3) as inputs to a seasonally and regionally differentiated glacier model(4,5). Unde r specified greenhouse-gas and sulphate-aerosol forcings, our model pr edicts that glacier melt equivalent to 132 mm of sealevel rise will oc cur over the period 1990-2100, with a further 76 mm from melting of th e Greenland ice sheet. These figures fall within the range of previous estimates made using simpler models(1); the advantage of our approach is that we take into account the effects of regional and seasonal tem perature variations. Our inclusion of these effects increases the calc ulated glacier melt by 20%.