Jet streams are relatively narrow bands of strong winds in the upper atmosphere, usually occurring around 30,000 feet, and blowing west to east. Their normal flow leads to week-to-week weather differences, which are modulated in mid-latitudes by the ridges and troughs of the jet stream. A high pressure ridge, for example, produces clear, warmer weather conditions; a trough is usually followed by stormy conditions. Together, these form waves in the jet stream that can stall as the waves grow and become more amplified, causing “forced” weather patterns that produce longer storms and heat waves.
New research published in Communication in Nature describes observations that link increased warming in high latitudes and the constant reduction of snow cover in North America to these stalls in atmospheric circulation.
“These persistent and extreme conditions are thought to increase in the future as a result of this increased waviness of the jet stream,” said lead study author Jonathon Preece, a postdoctoral researcher at the University of Georgia.
Since 2000, persistently “stuck” weather patterns have produced heat waves in Greenland, resulting in unprecedented melting of the Greenland Ice Sheet. Contrary to these observations, global climate models actually project a slight reduction in the blocking patterns in Greenland and, consequently, the models underrepresent the contribution of meltwater runoff from the ice sheet to the global sea level rise.
“These patterns often create melting pulses on the surface of the Greenland ice sheet that account for a large part of the annual melting,” said study co-author Marco Tedesco, a professor at the Columbia Climate School’s Lamont-Doherty Earth Observatory, and lead principal investigator on the project. “Accounting for such an aspect is important for anticipating not only how much but how fast Greenland will contribute to sea level rise.”
“One question is whether this is a consequence of climate change that we can expect to continue in the future [that] the climate models fail to resolve,” said Preece. “Or are the climate models correct, where we expect things to return to normal and perhaps the rate of accelerated melting of the ice sheet will slow down?”
The new study presents evidence of a link to climate change, to increases in jet-stream waviness and the springtime decline in North American snow cover extent, which “affects the atmosphere in some way. which favors these blocked high-pressure systems. in Greenland,” Preece said.
Many studies highlight the discrepancy between climate models and observations. This study provides evidence of a direct connection between the observed shift in summertime atmospheric circulation in Greenland and enhanced warming at high latitudes.
“The new study is the first to our knowledge to show a direct connection between the observed changes in summer atmospheric circulation in Greenland and the reduction in spring snow cover, which is a something we can confidently say is the result of climate change,” said co-author Thomas Mote, a geographer at the University of Georgia.
Jonathon R. Preece et al, Summer atmospheric circulation in Greenland in response to Arctic amplification and reduction of spring snow cover, Communication in Nature (2023). DOI: 10.1038/s41467-023-39466-6
Provided by the Earth Institute at Columbia University
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Citation: Research links climate change to ‘lazier’ jet stream, leading to extreme weather (2023, July 17) retrieved on July 17, 2023 from https://phys.org/news/2023- 07-links-climate-lazier-jet-stream .html
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