Global Warming

Climate Change May Already Be Shifting Clouds Toward the Poles

The way clouds cover the Earth may be changing because of global warming, according to a study published Monday that used satellite data to track cloud patterns across about two decades, starting in the 1980s.

Clouds in the mid-latitudes shifted toward the poles during that period, as the subtropical dry zones expanded and the highest cloud-tops got higher. These changes are predicted by most climate models of global warming.

About 70 percent of our planet is covered by clouds, at any given moment. These constantly moving shape-shifters aren’t exactly easy for scientists to study.

Clouds aren’t as simple as their fluffy nature might suggest. To understand them, scientists have to track the behaviour of tiny water droplets, as well as huge masses of clouds that might be hundreds of miles wide. And climate modellers also have to take into account the fact that clouds can have two different effects on temperatures.

During daytime, if there are a lot of clouds present, thick clouds, then that will keep the temperature cooler, because clouds reflect incoming sunlight back to space. But thick clouds can also act like a blanket that keeps the Earth’s warmth in, which is the reason why a cloudy night won’t be as cold at the surface as a clear night.

It’s probably happening primarily because of two influences — human-produced global warming, and also the recovery from the cooling effect of two volcanic eruptions during that time frame.