Increasingly frequent and intense storms make it difficult to rebuild Arctic sea ice

He Arctic it is losing sea ice rapidly, more than expected, even during the winter months when temperatures are below freezing.

A new study has just been published in Natural climate change found it powerful storms calls atmospheric rivers They increasingly affect the Arctic in winter, slowing sea ice recovery and accounting for a third of all winter sea ice melt.

The research was led by scientists from the Department of Meteorology and Atmospheric Sciences of the Pennsylvania State UniversityUNITED STATES.

“The decline of the Arctic sea ice is one of the clearest evidences of the global warming of the last decades. Although temperatures in the Arctic are well below freezing, the decrease in sea ice in winter is still very significant. And our research shows that atmospheric rivers are a factor in understanding why,” explained Pengfei Zhang, assistant research professor of meteorology and atmospheric sciences at Penn State and lead author of the study.

The bone atmospheric rivers They carry large amounts of water vapor in narrow, ribbon-like storm systems that can span thousands of miles and produce extreme rainfall and flooding when they make landfall. These storms regularly affect mid-latitude coastal regions like California, where river weather events in January, for example, dumped more than 11 inches of rain.

Using satellite observations and climate model simulations, scientists have found that these storms are increasingly reaching the Arctic, particularly the Barents and Kara Seas off the northern coast of Norway there Russiaduring the winter ice season.

“We often think that the decrease in sea ice of the Arctic is a gradual process due to a gradual forcing such as the greenhouse effect. This study is important because it finds that the decrease in sea ice is due to episodic extreme weather events: atmospheric rivers, which have occurred with increased frequency in recent decades, in part due to global warming,” explained L. Ruby Leung, Battelle Fellow at Pacific Northwest National Laboratory and co-author of the paper.

There humidity hot carried by these storms increases long-wave down-draft radiation, or heat reflected back to Earth from the atmosphere, and produces rain, which can melt the thin, fragile ice cap that regrows during the winter months.

Using remote sensing satellite imagery, scientists have observed sea ice receding almost immediately after atmospheric river storms and have seen this phenomenon persist for up to 10 days. because of this merger As storms become more frequent, atmospheric rivers slow the seasonal recovery of Arctic sea ice.

“When this type of moisture transport occurs in this region, the effect is not limited to just the amount of rain or snow that falls, but also the powerful melting effect of ice. This is important because we have been losing arctic sea ice rapidly over the past decades, which has led to many unintended consequences, such as the warming of the region and the erosion of its coasts,” said Mingfang Ting, a professor at the Lamont Observatory. Doherty University and also co-author of the research.

“The loss of sea ice in the Arctic has broad implications“wrote the scientists. Open water can allow new, more direct river routes, but also trigger geopolitical disruptions between countries. Additionally, the melting of freshwater in the salty ocean can affect ocean circulation patterns that stabilize global temperatures.

“The melting of the sea ice has a huge impact on the climate system and on society, and our study revealed that the Arctic is an open system and that climate change is much more complicated than temperature variations alone can. ‘explain,” said Laifang Li, an assistant professor of meteorology and atmospheric science at Penn State and another of the paper’s co-authors.

Using wide-coverage climate models, scientists have determined that human-induced warming has increased the rate of atmospheric river storms in the Arctic.

But they also found that natural climate variability, called the Pacific Interdecadal Oscillation, is also a key contributor to atmospheric changes in rivers.

“This study, along with other work that has noted the presence of atmospheric rivers in the tropics, underscores that atmospheric rivers represent a global phenomenon. Since their relatively recent discovery in the 1990s, and even more recently in terms of recognition of their societal impacts, atmospheric rivers provide an opportunity for potentially globally coordinated research and applications using current technologies. concluded Bin Guan, an Earth systems scientist. at the University of California at Los Angeles and a member of the research team.

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