Projections of changes in climate extremes are critical to assessing the potential impacts of climate change on human and natural systems. Modeling advances now provide the opportunity of utilizing global general circulation models (GCMs) for projections of extreme temperature and precipitation indicators. We analyze historical and future simulations of ten such indicators as derived from an ensemble of 8 GCMs contributing to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4), under a range of emissions scenarios. Our focus is on the consensus from the GCM ensemble, in terms of direction and significance of the changes, at the global average and geographical scale. The climate extremes described by the ten indices range from heat-wave frequency to frost-day occurrence, from dry-spell length to heavy rainfall amounts. Historical trends generally agree with previous observational studies, providing a basic sense of reliability for the GCM simulations. Projections for the 21st century are unanimous in confirming the changes in most temperature indices that are expected within a warmer climate, with differences in the spatial distribution of the changes and in the rates of the trends detected across scenarios. Depiction of a wetter world emerges unequivocally in the global averages of most of the precipitation indices. However, consensus and significance are less strong when regional patterns are concerned. This analysis provides a first overview of projected changes in climate extremes from the IPCC-AR4 model ensemble, and has significant implications with regard to climate projections for impact assessments.

Full Article: http://www.springerlink.com/content/08l058mt1k828814/?p=bc36ea475e86483fb6c910ca8fb427fa&pi=17

Last Updated: 2007-09-11