In recent years, arctic air bursts and major blizzards have been occurring with increasing frequency in the eastern United States. Some climate change deniers, including those with political power, have pointed to this as evidence disproving that the Earth is warming. Senator James Inhofe famously brought a snowball onto the Senate floor in 2015, suggesting that because it was cold and snowy outside, global warming couldn’t possibly be that bad.
Ignoring the fact that the senator was describing weather and not climate, the evidence he used was actually describing an outcome of human-caused climate change. Climate models counterintuitively predict that global warming can cause harsher winters in the United States.
One of the biggest determinants of whether a winter will be particularly cold across the United States is the strength of the polar jet stream. A jet stream is like a river of wind high up in the atmosphere (around where planes cruise) that controls weather patterns. When a jet stream is strong, it tends to remain fairly stationary and acts as a boundary between cold and warm air masses. Jet streams derive their strength from temperature gradients–the greater the difference in temperature between two regions, the stronger the jet stream. Since the Arctic region is warming the fastest of any place on Earth, there is increasingly less of a temperature gradient between the Arctic and regions to the south. This results in a weaker, less stable jet stream which wavers north and south more easily, allowing for arctic air to dump into the United States.
Additionally, a weaker jet stream tends to get “stuck” in a particular formation, meaning that cold air is allowed to continuously invade the United States once the jet stream moves south.
When the jet stream is positioned right off the East Coast, it can also result in heavy snowfalls in the major I-95 cities (including where Senator Inhofe works in Washington, D.C.). The large temperature gradient between the warm Atlantic Ocean and cold inland allows for large storms to spin up, and then track right along the coast as it follows the jet stream.
As a result of all this, the senator is right about one thing – winters have certainly become snowier in this part of the country. In New York City, seven of the ten heaviest snowfalls on record have occurred within the last 25 years, with records going back to 1869. Washington, D.C. recently recorded its snowiest winter in 2009-2010. During that winter, multiple record-breaking snowstorms brought 56.1 inches of snow to the city, nearly four times the annual average of 15.4 inches. The 2009-2010 winter was significantly colder in much of the eastern U.S. because of the weak polar jet stream, as illustrated in the NOAA graphic below.
Warmer than average temperatures (orange and red on the map) shown over northeastern Canada and Greenland caused the polar jet stream to weaken significantly during the winter months and displaced large amounts of arctic air (blue and purple) into the central and eastern United States.
Weather patterns such as these may seem contradictory to the fact that humans have accelerated the rate of global warming. What we must remember, however, is that global warming is a climatic trend. Weather changes on a daily basis, and even in a warming world, there can still be cold winters. As the world continues its warming trend, however, these winters will decrease in frequency. Heavy snowfalls and Polar chills don’t disprove the validity of global warming research, but also actually a part of the increasingly unstable weather patterns we can expect from the climate crisis.Share This