This past year, the US generated 300 billion kilowatt-hours from wind turbines. That’s 7.3% of the country’s electricity demand, more power than is produced by any other renewable technology, including hydroelectricity. Although the turbines don’t pollute the air with greenhouse gases, many recent studies conclude that they nonetheless warm the lower atmosphere near the ground—albeit temporarily and at night.
Wind turbines now reach heights of 300 m, with each blade 50 m in length—half a football field. The US has about 60 000 turbines and that number will increase as they are deployed in clusters up to thousands per county to reach future power targets. As they harvest kinetic energy, those turbines reduce wind speeds and introduce wake turbulence, which in turn alters the exchange of heat, moisture, and momentum between Earth’s surface and the lower atmosphere. Curiously, the effects don’t appear limited to the turbines’ immediate vicinity; they are...
