TITLE:
Projection of Future Climate over the Koshi River Basin Based on CMIP5 GCMs
AUTHORS:
Rupak Rajbhandari, Arun Bhakta Shrestha, Santosh Nepal, Shahriar Wahid
KEYWORDS:
Climate Projection, Climate Change, Himalaya, Koshi, Future Scenario
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.6 No.2,
March
28,
2016
ABSTRACT: This paper analyses the climate projections
over the Koshi river basin obtained by applying the delta method to eight CMIP5
GCMs for the RCP4.5 and RCP8.5 scenarios. The GCMs were selected to cover the
full envelope of possible future ranges from dry and cold to wet and warm
projections. The selected coarse resolution GCM outputs were statistically
downscaled to the resolution of the historical climate datasets. The scenarios
were developed based on the anomaly between the present reference period
(1961-1990) and the future period (2021-2050) to generate transient climate
change scenarios for the eight GCMs. The analyses were carried out for the whole
basin and three physiographic zones: the trans-Himalaya, high-Himalaya and
middle mountains, and southern plains. Future projections show a 14% increase
in rainfall during the summer monsoon season by 2050. The increase in rainfall
is higher over the mountains than the plains. The meagre amount of rainfall in
the winter season is projected to further decrease over both the mountain and
southern plains areas of the basin for both RCPs. The basin is likely to
experience warming throughout the year, although the increase in winter is
likely to be higher. The highest increase in temperature is projected to be
over the high Himalayan and middle mountain area, with lower increases over the
trans-Himalayan and southern plains areas.