Visualization of a very wavy Northern Hemisphere jet stream. (NASA)
Ever since 2012, scientists have been debating a complex and frankly explosive idea about how a warming planet will alter our weather — one that, if it’s correct, would have profound implications across the Northern Hemisphere and especially in its middle latitudes, where hundreds of millions of people live.
The idea is that climate change doesn’t merely increase the overall likelihood of heat waves, say, or the volume of rainfall — it also changes the flow of weather itself. By altering massive planet-scale air patterns like the jet stream (pictured above), which flows in waves from west to east in the Northern Hemisphere, a warming planet causes our weather to become more stuck in place. This means that a given weather pattern, whatever it may be, may persist for longer, thus driving extreme droughts, heat waves, downpours and more.
This basic idea has sparked half a decade of criticism and debate, and at the cutting edge of research, scientists continue to grapple with it. And now, a new study once again reinforces one of its core aspects.
Publishing in Nature Scientific Reports, Michael Mann of Pennsylvania State University and a group of colleagues at research institutes in the United States, Germany and the Netherlands find that at least in the spring and summer, the large scale flow of the atmosphere is indeed changing in such a way as to cause weather to get stuck more often.
The study, its authors write, “adds to the weight of evidence for a human influence on the occurrence of devastating events such as the 2003 European heat wave, the 2010 Pakistan flood and Russian heat wave, the 2011 Texas heat wave and recent floods in Europe.”
But what does it mean for global warming to alter the jet stream? The basic ideas at play here get complicated fast. The study itself, for instance, refers to “quasi-resonant amplification (QRA) of synoptic-scale waves” as the key mechanism for how researchers believe this is happening — terminology sure to impart terror in nonscientists worldwide.