This week, parts of the United States will likely see the coldest weather in two decades. At first glance it doesn’t make sense: how can global warming exist along with a dangerous cold snap? After all, the current polar vortex is bringing temperatures that will rival Arctic and Siberian conditions.
The term “global warming” refers to the rise in temperature that occurs when greenhouse gasses — such as carbon and methane — trap warm air in the atmosphere. Drought, floods and wildfires are obvious examples of extreme conditions linked with global warming. But how can scientists continue to warn about global warming in the midst of blizzards and life-threatening cold?
Well, it turns out that higher-than-normal temperatures in the Arctic regions are contributing to the polar vortex in the Midwest and eastern United States. When Arctic temperatures rise, a warm ridge forms in the atmosphere and drives the jet stream farther south. The result? Cold temperatures that break records and affect southern regions.
Warmer temperatures worldwide also increase the amount of water vapor in the atmosphere. Combined with a plunging jet stream, the increased moisture levels bring heavy snowfall and blizzards.
If you’d like to read more about weather extremes, here are some good places to start: