Publication Date:
2015-07-09
Description:
Daily moderate rainfall events, that constitute a major portion of seasonal summer monsoon rainfall over central India, have decreased significantly during the period 1951 till 2005. Mean and extreme near surface daily temperature during the monsoon season have also increased by a maximum of 1–1.5 °C. Using simulations made with a high-resolution regional climate model (RegCM4) with prescribed vegetation cover of 1950 and 2005, it is demonstrated that part of the above observed changes in moderate rainfall events and temperature have been caused by land-use land-cover change (LULCC) which is mostly anthropogenic. Model simulations show that the increase in seasonal mean and extreme temperature over central India coincides with the region of decreased (increased) forest (crop) cover. The results also show that land-use land-cover alone causes warming in the extremes of daily mean and maximum temperatures by maximum of 1–1.2 °C, that is comparable with the observed increasing trend in the extremes. Decrease (increase) in forest (crop) cover reduces the evapotranspiration over land and large-scale convective instability, apart from decreasing the moisture convergence. These factors act together not only in reducing the moderate rainfall events over central India but also the amount of rainfall in that category, significantly. This is the most interesting result of this study. Additionally, the model simulations are repeated by removing the warming trend in sea surface temperatures. As a result, there is enhanced warming at the surface and decrease in moderate rainfall events over central India. Results from the additional experiments corroborate our initial findings and confirm the contribution of land-use land-cover change on increase in daily mean and extreme temperature and decrease in moderate rainfall events. This study not only demonstrates the important implications of LULCC over India, but also shows the necessity for inclusion of projected anthropogenic changes in land-use land-cover in future climate change scenarios for developing better adaptation and mitigation strategies.
Print ISSN:
1812-2108
Electronic ISSN:
1812-2116
Topics:
Geography
,
Geosciences
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