Study Links Climate Change to Inert Jet Stream, Driving Extreme Weather
The jet stream is a relatively narrow band of strong winds in the upper atmosphere, usually occurring around 30,000 feet and blowing from west to east. Their normal flow causes weekly weather variations, moderated in mid-latitudes by ridges and troughs in the jet stream. For example, a ridge of high pressure produces sunny, warm weather conditions; a trough is often followed by stormy weather. Together these form waves in the jet stream that can stall as the waves grow and become more amplified, causing “stagnation” weather patterns that produce longer storms and heat waves.
New research published in natural communication Observations linking increased warming at high latitudes and decreasing snow cover in North America to atmospheric circulation loss are described.
“These persistent and extreme conditions are expected to increase in the future due to increased jet stream volatility,” said Jonathan Price, the study’s lead author and a postdoctoral fellow at the University of Georgia.
A ridge of high pressure over Texas, 2018. (wind chimes)
Since 2000, frequent “stuck” weather patterns have produced heat waves in Greenland, leading to unusual weather. Greenland ice sheet melting. In contrast to these observations, global climate models actually predict a slight reduction in blocking patterns in Greenland, and thus, these models underestimate the contribution of ice sheet meltwater runoff to global sea level rise.
“These patterns have been generating melt pulses across the Greenland ice sheet, accounting for a large fraction of annual melt,” said study co-authors. Mark GermainProfessor at Columbia Climate Institute Lamont-Doherty Earth Observatory, and lead the principal investigator of the project. “Taking this aspect into account is critical to predicting the magnitude and rate of Greenland’s contribution to sea level rise.”
“One question is whether this is a consequence of climate change, which we expect to continue in the future [that] “Climate models can’t figure that out,” Price said. “Or are climate models right that, in this case, we’d expect things to return to normal, with perhaps a tapering off of the accelerated melting of the ice sheet?” “
The new study provides evidence of a link to climate change, including increased jet stream fluctuations and diminishing spring snow extent in North America, which “is affecting the atmosphere in ways that favor these clogged high-pressure systems” in Greenland, says P. Reese said.
Several studies have highlighted discrepancies between climate models and observations. The study provides evidence of a direct link between observed changes in Greenland’s summertime atmospheric circulation and increased warming at high latitudes.
“To our knowledge, this new study is the first to demonstrate a direct link between observed changes in Greenland’s summertime atmospheric circulation and reduced spring snowpack, which we can confidently say is a consequence of climate change,” said co-author Thomas. Mott is a geographer at the University of Georgia.
Adapted from a press release from the University of Georgia.
