Global Warming and Airflow Changes Linked to Extreme Weather

Heat waves, hurricanes and flooding have plagued the U.S. the past several years, and now scientists may have a reason why. New research has shown that global warming could be linked to more extreme weather events. How? It's all about the air.

Earth possesses an atmosphere with global air currents, similar to the massive currents seen in our oceans. In the mid-latitudes, these currents take the form of waves that wander around the planet, oscillating between the tropical and Arctic regions. When they swing upward, the waves suck warm air from the tropics to areas such as Europe, Russia or the U.S. When they swing downward, they do the same thing with cold air from the Arctic.

Yet it seems that global warming may be having an effect on these air currents. The researchers found that during several recent extreme weather events, these waves tended to almost freeze in their tracks for weeks. Instead of bringing cold air after bringing warm air in before, for example, the heat just continued.  In fact, they actually showed that these events have actually been increasing in occurrence.

In order to examine this phenomenon, the scientists of the study developed equations that describe the wave motions in the extra-tropical atmosphere. These equations showed under what conditions these waves could grind to a halt and become amplified. They then tested these equations by using daily weather data from the U.S. National Centers for Environmental Prediction (NCEP). They found that during several events where major weather extremes occurred, their equations held true. The data, in fact, showed an increase in the occurrence of these particular atmospheric patterns, which is statistically significant--a 90 percent confidence level.

Hans Joachim Schellhuber, co-author of the study, said in a press release, "This is quite a breakthrough, even though things are not at all simple-- the suggested physical process increases the probability of weather extremes, but additional factors certainly play a role as well, including natural variability." 

The analysis actually helped explain the increasing number of novel weather extremes. It also complimented previous research that already linked this kind of phenomena to climate change, but did not identify a mechanism behind it. It shows significant advances in the understanding between weather extremes and human-made climate change, and shows that in the future, we'll probably be in for some more extreme weather.

The study was published in the Proceedings of the National Academy of Sciences.