Water Always Wins

Oceans have absorbed more than 90 percent of the excess heat since the 1970s. Warmer seawater, especially in tropical areas, evaporates more readily, increasing air temperature and humidity, leading to increased rain in some areas. Warmer air also evaporates more water out of soil and freshwater bodies and allows the atmosphere to hold more water. That’s because the molecules of vapor are moving faster than those in colder air, making them less likely to condense back into liquid to fall as rain. For each Celsius-degree increase of warming, the air holds about 7 percent more vapor. And because water vapor is itself a greenhouse gas, more water in the air creates a feedback loop, further warming the globe and accelerating climate change. But while some places are getting more rain, others are experiencing increased water scarcity. Warmer temperatures are also drying out the land through evapotranspiration.