Climate change is now a daunting reality which is expected to adversely affect the global water cycle. Subsequently, availability of water is expected to be reduced in many parts of the world just due to rising global temperatures. These changes could threaten the water and food security of human beings as well as the flora and fauna around us, jeopardising human life and ecosystems alike.
Water availability in a region can be denoted by the total water annually recharging the natural water bodies above and below the ground level such as lakes, rivers, groundwater, etc. In a new study, researchers at IISc and University of New South Wales used satellite-derived estimates of total annual recharge to investigate the effect of rise in temperature for areas drained by 31 major rivers around the world. These include the Amazon, Ganga, Brahmaputra, Indus, Nile, Tigris-Euphrates, Mekong and Mississippi, alongside which most of the global population resides.
The researchers find that the areas drained by 23 out of these 31 rivers show reduced recharge with increase in temperature. Vegetation growth was also found to reduce due to decline in the annual water recharge. Given that this is a result of just 0.9oC rise in global temperature, the impact of the 3.5oC rise by the end of this century that is expected is a major concern.
The findings of this work, based on Gravity Recovery and Climate Experiment (GRACE) satellite observations,are first of their kind and in line with future projections from mathematical models.
Chandan Banerjee, Ashish Sharma, Nagesh Kumar D, Decline in terrestrial water recharge with increasing global temperatures, Science of the Total Environment (2020).