Climate change, though, doesn’t just bring more rain. While some of the wettest parts of the world are seeing heavier and more unpredictable precipitation, scientists say, some drier parts of the planet are becoming measurably drier.
The combination can be dangerous.
In India, for instance, even as total annual rainfall has dipped slightly, bursts of intense rain are becoming more powerful, one recent study concluded. Another group of researchers drilled down to find that, in the center of India between 1950 and 2015, there was a threefold increase in what were once rare cloudbursts, those that dump 150 millimeters, or nearly six inches, or more of rain on a single day.
Lisa Goddard, director of the International Research Institute at Columbia University, compared the atmosphere to “a big giant sponge” that grows heavy with moisture and, at some point when it’s too heavy, has to be squeezed out, resulting in intense rains.
The results can be overwhelming. If emissions continue to rise and global temperatures grow by 2 degrees Celsius, the mighty Ganges River could double in volume, with devastating consequences for the hundreds of millions of people who live in its basin.
All that unpredictability creates painful choices for government officials who manage reservoirs and dams: Whether to store water in case of drought, or release it to avert floods.
Take Kerala, one of India’s richer states, for instance. Its record rains this summer followed a long dry spell. After years, the reservoirs were good and full. And even though meteorologists warned of unusually heavy rains in August, dam operators did not open the floodgates in advance. It was a difficult call: What if the forecasts were wrong? What if the rains didn’t come?