CR 19:179-192 (2002)  -  doi:10.3354/cr019179

Future climate change and its impacts over small island states

Murari Lal1,*, Hideo Harasawa2, Kiyoshi Takahashi2

1Centre for Atmospheric Sciences, Indian Institute of Technology, New Delhi, 110016 India
2National Institute for Environmental Studies, Ibaraki, Japan

ABSTRACT: This paper examines the response of the climate of Small Island States (SIS) to transient increases in anthropogenic radiative forcing due to increases in atmospheric concentrations of greenhouse gases and/or sulfate aerosols using the data generated in a set of numerical experiments performed with a range of coupled atmosphere-ocean global climate models. Five of the 7 models considered in our validation exercise are found to have fair skill as regards their ability to simulate the broad features of present-day observed surface climatological features over the SIS in the Indian Ocean, the Mediterranean Sea, the Atlantic Ocean and the Pacific Ocean. The transient experiments with these models, which include the time-varying future anthropogenic radiative forcings, have been used here to develop regional projections of future climate change. An area-averaged annual mean warming of ca 2°C or higher for the 2050s and ca 3°C or higher for the 2080s are projected for the SIS as a consequence of increases in atmospheric concentration of greenhouse gases. In general, seasonal variations of the projected surface warming over the SIS are minimal. No significant change in diurnal temperature range is likely with an increase in surface temperatures. An increase in mean temperature would be accompanied by an increase in the frequency of extremely high temperatures. The aerosol forcing will only marginally reduce the surface warming. The models simulate only a marginal change (<10%) in annual mean rainfall over most of the SIS. During the northern hemisphere summer, however, rainfall is projected to decline (except over Pacific Ocean islands). An increase in daily rainfall intensity leading to more heavy rainfall events is also projected. The projected changes in temperature and rainfall could disrupt the terrestrial and marine ecosystems in most SIS. An integrated study of vulnerability assessment for SIS based on a better understanding of the precise magnitude of increase in surface air temperature and associated sea level rise is warranted for developing appropriate adaptation strategies.

KEY WORDS: Global climate models · Regional climate change · Small Island States · Anthropogenic radiative forcings · Impact Assessment · Sea level rise

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