Research Links Climate Change to Lazier Jet Stream, Resulting in Extreme Weather
Jet streams are relatively narrow bands of strong wind within the upper atmosphere, typically occurring around 30,000 feet, and blowing west to east. Their normal flows result in week-to-week weather variations, modulated within the mid-latitudes by ridges and troughs within the jet stream. A high-pressure ridge, for instance, produces clear, warmer weather conditions; a trough is often followed by stormy conditions. Together, these form waves within the jet stream that may stall because the waves grow and change into more amplified, causing “stuck” weather patterns that produce longer storms and warmth waves.
Recent research published in Nature Communications describes observations linking increased warming at high latitudes and the ever-decreasing snow cover in North America to those stalls in atmospheric circulation.
“These persistent and extreme conditions are considered increasing in the longer term because of this of this increased waviness within the jet stream.” said the study’s lead creator Jonathon Preece, a postdoctoral researcher on the University of Georgia.
High-pressure ridge over Texas, 2018. (Weatherbell)
Since 2000, frequent “stuck” weather patterns have produced heat waves over Greenland, leading to exceptional melting of the Greenland Ice Sheet. In contrast to those observations, global climate models actually project a slight decrease within the blocked patterns over Greenland and, consequently, the models have underrepresented the contribution of meltwater runoff from the ice sheet to global sea level rise.
“These patterns have been consistently creating pulses of melting over the Greenland ice sheet which have been accounting for a big portion of the annual melting,” said study coauthor Marco Tedesco, a professor at Columbia Climate School’s Lamont-Doherty Earth Observatory, and lead principal investigator on the project. “Accounting for such a facet is crucial for anticipating not only how much but how briskly Greenland is and can be contributing to sea level rise.”
“One query is whether or not this can be a consequence of climate change that we are able to expect to proceed in the longer term [that] the climate models are failing to resolve,” said Preece. “Or are the climate models correct, by which case we’d expect things to revert back to the norm and maybe the speed of accelerated melt of the ice sheet will taper some?”
The brand new study presents evidence of a link to climate change, each within the increases in jet-stream waviness and ever-decreasing spring North American snow cover extent, which “is impacting the atmosphere in a way that’s favoring these blocked high-pressure systems over Greenland,” Preece said.
Multiple studies have highlighted the discrepancy between climate models and observations. This study provides evidence of a direct connection between the observed shift in summer atmospheric circulation over Greenland and amplified warming at high latitudes.
“The brand new study is the primary that we all know of that demonstrates a direct link between the observed change in summer atmospheric circulation over Greenland and diminished spring snow cover, which is something we are able to confidently say is a consequence of climate change,” said coauthor Thomas Mote, a geographer on the University of Georgia.
Adapted from a press release by the University of Georgia.
