Climate and Climate Change Scenarios in the Indian Thar Region

Abstract

The Thar Desert region of India, which extends in more than 2.0 lakh sq. km area, experiences variable rainfall from 100 mm to 450 mm in a year. Frequent drought, which occurs once in 2 or 3 years in the region, causes extreme stress to fauna due to limited seasonal grazing resources. Besides the xerophytic type of ecosystem, the fauna in the Thar Desert is subjected to extreme diurnal and seasonal variation in temperatures ranging as low as −5 °C in winter to a high of +49 °C in summer, causing thermal stress to the fauna. The Intergovernmental Panel on Climate Change (IPCC 2007) projected for hotter days and warm nights and a reduction in rainfall in the Thar region by the twenty-first century. Such projected climate change results in shifting rainfall pattern, higher temperatures, and more demand for water and will be significant driver of biodiversity with changing life cycles, loss, migration, and invasion of new habitat in the Thar region. The present study on annual rainfall and temperature for the Thar region showed, by the end of the twenty-first century, an increase in temperature by +3.3 °C at Bikaner, +3.4 °C at Jaisalmer, +2.9 °C at Jodhpur, and +2.3 °C at Pali, if the present rate of warming continues. Similarly, though there was no significant rise (at 0.56 mm/year) in the annual rainfall of 12 arid districts of western Rajasthan, the annual rainfall is likely to be increased by +100 mm at Bikaner, +124 mm at Jaisalmer, −40 mm at Jodhpur, and +21 mm at Pali. The spatial and temporal variation in potential evapotranspiration requirement of the Thar region ranged from 2.1 mm/day to 12.2 mm/day and on an annual basis between 1500 mm and 2220 mm. Further, due to global warming, if the projected temperatures rise by 4 °C, by the end of the twenty-first century, water requirement in arid Rajasthan increases from the current level, by 12.9% for pearl millet and cluster bean, 12.8% for green gram, 13.2% for moth bean, 17.1% for wheat, and 19.9% for mustard.