While the region is expected to receive heavy rainfall, it will be too slow to result in significant changes in runoff demand, researchers said
Extreme hot and dry climate combined with population explosion is likely to cause scarcity of food and water for up to 250 million people living along Nile, the world’s longest river, according to a study.
For thousands of years, Nile has been an oasis of water, food, commerce, transportation and energy.
But, the region has been frequently facing hot and dry years since the last 40 years. This frequency is projected to increase from 10 per cent to 15 per cent, even if emissions are curbed as per Paris climate Agreement, according to the study published in the journal Earth’s Future.
It can lead to poor crop yields and cause food scarcity in the region, it added.
“Despite some uncertainties in the models, this trend is projected to continue throughout the century with the frequency of hot and dry years as much as tripling even if warming is limited to only 2 degrees Celsius,” the study showed.
The upper Nile region that includes western Ethiopia, South Sudan, and Uganda — a chronically water-stressed region — is already home to nearly 200 million people. This number is expected to nearly double by 2080, according to researchers.
As a result of the additional demands on water resources about 65 per cent of the regional population — 250 million people — could face chronic water scarcity by 2080, the study said.
Further, some climate models have indicated that rise in atmospheric moisture, due to global warming, can result in high rainfall in the Upper Nile Basin.
However, the trend of increased precipitation will be too slow to result in significant changes in runoff demand, the researchers said.
“At first glance you would expect more rain to reduce scarcity, but not on the Nile. The dice are loaded for additional hot and dry years in the future, meaning increasing shocks to households because of crop yield declines and less water available for households to be resilient against warming temperatures,” said Justin Mankin, an assistant professor of geography at Dartmouth and senior researcher on the study.
Hot and dry weather as a result of climate change will be countered by the increase in precipitation in coming decades.
Figure credit: Richard Clark/Dartmouth College. Nile River. Image credit: Jacques Descloitres, NASA/GSFC.
The study also stated that about 170 million people on average could be affected by water scarcity annually by the latter part of the century, while water demands of less than 25 million people will be unmet by 2020. The population is expected to rise rapidly between 2020 and 2040 and as a result lead to an increase in water demand.
“The Nile Basin is one of several fast growing, predominantly agricultural regions that is really on the brink of severe water scarcity. Climate change coupled with population growth will make it much harder to provide food and water for everyone in these areas. Those environmental stresses could easily contribute to migration and even conflict,” said Ethan Coffel, a fellow at Dartmouth’s Neukom Institute for Computational Science and lead author of the study.
To explain further, the researchers assessed agricultural yields data from six major crops in Ethiopia’s food supply: maize, millet, barley, pulses, sorghum, and wheat. They found that nearly all crop failures occurred during hot and dry conditions and when water was scarcer.
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