Study: South Asia's Irrigation is Africa's Rain
Agricultural irrigation is so widespread that it accounts for about 4% of the total evapotranspiration of water from Earth’s surface. Scientists have known for some time that water vapor from irrigation affects regional and global climates. Now, for the first time, researchers have shown that irrigation in one region can directly affect the climate of another region thousands of kilometers away.
De Vrese et al. used the Max Planck Institute for Meteorology’s Earth System Model to simulate the fate and impact of water used for irrigation in South Asia from 1979 to 1999. In the simulations, early spring winds carried water vapor from irrigation in South Asia across the Arabian Sea and into East Africa, increasing humidity there. By late spring, when irrigation in the Middle East, Turkmenistan, and Afghanistan is in full swing, wind transported water vapor into Africa, increasing humidity as far west as Nigeria.
Kannan Muthuraman