Human effects on the global climate system, principally through changing the atmospheric concentrations of carbon dioxide and other greenhouse gases, are expected to lead to significant warming and other associated changes in the climate worldwide. Human-induced climate changes are likely already observable in quantities such as the global mean temperature, and over the next century can be expected to include significant effects on the local environment in Hawaii and other Pacific Islands. The currently available climate change projections from global coupled atmosphere/ocean models, as summarized for example in the recent IPCC assessment reports, have very limited direct application to Hawaii or other Pacific islands, as they have been performed with atmospheric models with coarse spatial resolution and hence completely inadequate representation of any of the Pacific islands. This project has used the output from standard global climate models as the basis for much finer scale regional climate simulations for Hawai`i. We have performed computer model simulations representing present day conditions and conditions at the end of the present century. Our projections indicate a warming of the long term mean near-surface air temperature over the Hawaiian islands of order 4-6 F with the largest warming expected near the summits of Haleakala, Mauna Kea and Mauna Loa. Mean rainfall patterns are also projected to change significantly, with an overall pattern of increased rainfall over areas that now have high mean rainfall and decreasing rainfall over currently dry areas. The results of this study are now being used as input to efforts conducted by other researchers to assess the effects of these projected climate changes on aspects of the natural and manmade environments of interest to Hawaii residents including freshwater availability, geographical distributions of plant species, agricultural practices, geographical distribution of avian malaria and consequent effects on native bird populations.
