Climate Change Projections Over Sri Lanka

Abstract

This paper investigates the future climate of Sri Lanka using the variable-resolution Conformal Cubic Atmospheric Model (CCAM) developed at CSIRO, Australia. Bias corrected sea surface temperatures (SSTs) and sea ice concentration from a few global climate models (GCMs) such as CNRM-CM5, GFDL-CM3 and ACCESS1-0 from the CMIP5 simulations were used as boundary conditions for simulations at 8 km horizontal resolution. Mean biases, root mean square errors (RMSE) and pattern correlations have been calculated by comparing with observations to assess the performance of the model. The results show that the temperature biases range between 00C and -30C. Pattern correlations vary among the seasons between 0.96 and 0.92. The model tends to underestimate the observed values over the selected domain. The CCAM simulations show small bias values during the northeast season with strong pattern correlations of 0.75 and RMSE values of 1.7 mm/day. The pattern correlation of rainfall is relatively low for the southwest monsoon season with 0.68 and RMSE about 3.9 mm/day. Projected changes in mean temperature and rainfall are presented for 2050. Area average temperature is expected to increase by 10C under the high level emission scenario (RCP 8.5). The rainfall changes show increase of about 40% in the northern part of the country during the first inter-monsoon season and about 20% in the south eastern part of the country during the northeast monsoon season by 2050.