Quote: Extreme weather, an unusual jet stream, and climate change

The extreme weather we're seeing around the Northern Hemisphere, such as heat waves, floods, droughts, and wildfires, is related to an unusual, undulating pattern in the jet stream. The other part of this that's atypical is that this undulating pattern doesn't usually hold longer than a few days. But this one isn't going anywhere. Our work shows that this sort of pattern, which has been associated with many of the most extreme, persistent weather events in recent years, including the 2003 European heatwave, the 2010 Moscow wildfires, the 2011 Texas and Oklahoma drought, and the 2016 Alberts wildfires to name a few, is becoming more common because of human-caused climate change, and in particular, because of amplified Arctic warming.

Michael E. Mann is Distinguished Professor of Atmospheric Science at Penn State, with joint appointments in the Department of Geosciences and the Earth and Environmental Systems Institute (EESI). He is also director of the Penn State Earth System Science Center (ESSC).