Climate change is expected over the next century as a result of anthropogenic emissions of greenhouse gases and aerosols into the atmosphere, and global average sea level will consequently rise. Estimates＇ indicate 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 accounting for over half of this rise. The melting of glaciers and ice sheets will contribute much of the remainder. We present an improved calculation of glacier melt, which uses the temperature patterns generated by a coupled atmosphere-ocean general circulation model(2,3) as inputs to a seasonally and regionally differentiated glacier model(4,5). Under specified greenhouse-gas and sulphate-aerosol forcings, our model predicts that glacier melt equivalent to 132 mm of sealevel rise will occur over the period 1990-2100, with a further 76 mm from melting of the 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 temperature variations. Our inclusion of these effects increases the calculated glacier melt by 20%.