J.C. Moore Online

Current Events from a Science Perspective

It is difficult to explain how global warming can cause some of the extremely cold weather we have been experiencing. The Arctic is warming much faster than the rest of the earth. The warmer Arctic destabilizes and weakens the jet stream, causing it to pull frigid air down from the Arctic into the United States.

The weaker the jetstream, the slower the loops (called Rossby Waves) move from West to East. This causes the polar vortex pattern to persist longer over the United States. This is like a weather event – and when it will happen is difficult to predict. However, all indications are that we will have many more such events as the Arctic warms.

The Arctic is much warmer now than it was 30 years ago. They even had 100° days in Siberia last summer. The warming Arctic has caused changes in the jet stream, which controls the Northern Hemispheres’ weather. The Rossby waves in the jet stream,  that move from west to east across the United States, (see picture), now come down further and move slower from west to east.

This means that the jet stream can sometimes pull Arctic air down from the Arctic region, called a Polar Vortex. The slower movement of the Rossby Waves causes the extreme cold to persist for longer. It is 3° today in Kansas, the windchill is -15°, and this cold spell will persist for about a week. If it is extremely cold and snowy where you live, you can thank global warming for that.