{"id":88914,"date":"2023-02-08T02:42:00","date_gmt":"2023-02-08T01:42:00","guid":{"rendered":"https:\/\/www.sonnenseite.com\/?p=88914"},"modified":"2023-02-07T10:42:48","modified_gmt":"2023-02-07T09:42:48","slug":"more-frequent-atmospheric-rivers-hinder-seasonal-recovery-of-arctic-sea-ice","status":"publish","type":"post","link":"https:\/\/www.sonnenseite.com\/en\/science\/more-frequent-atmospheric-rivers-hinder-seasonal-recovery-of-arctic-sea-ice\/","title":{"rendered":"More frequent atmospheric rivers hinder seasonal recovery of Arctic sea ice"},"content":{"rendered":"\n

The Arctic is rapidly losing sea ice, even during winter months when temperatures are below freezing and ice should be recovering from the summer melt. A new study found powerful storms called atmospheric rivers are increasingly reaching the Arctic in winter, slowing sea ice recovery and accounting for a third of all winter sea ice decline, according to a team led by Penn State scientists.<\/p>\n\n\n\n

\u201cArctic sea ice decline is among the most obvious evidence of global warming from the past several decades,\u201d said Pengfei Zhang, assistant research professor of meteorology and atmospheric science at Penn State and lead author of the study. \u201cDespite temperatures in the Arctic being well below freezing, sea ice decline in winter is still very significant. And our research shows atmospheric rivers are one factor in understanding why.\u201d<\/p>\n\n\n\n

Atmospheric rivers carry large amounts of water vapor in narrow, ribbon-like storm systems that can stretch for a thousand miles and produce extreme rainfall and flooding when they make landfall. These storms regularly impact midlatitude coastal regions like California, where atmospheric river events in January, for example, dropped 11 inches of rain.<\/p>\n\n\n\n

Using satellite observations and climate model simulations, the scientists found these storms are increasingly reaching the Arctic \u2014 particularly the Barents and Kara seas off the northern coasts of Norway and Russia \u2014 during the winter ice-growing season. They reported their findings Monday, Feb. 6, in the journal Nature Climate Change<\/a>.<\/p>\n\n\n\n

\u201cWe often think that Arctic sea ice decline is a gradual process due to gradual forcings like global warming,\u201d said L. Ruby Leung, Battelle Fellow at Pacific Northwest National Laboratory, and a co-author. \u201cThis study is important in that it finds sea ice decline is due to episodic extreme weather events \u2014 atmospheric rivers, which have occurred more frequently in recent decades partly due to global warming.\u201d<\/p>\n\n\n\n

Warm moisture carried by these storms increases downward longwave radiation, or heat emitted back to Earth from the atmosphere, and produces rain, both of which can melt the thin, fragile ice cover regrowing during the winter months.<\/p>\n\n\n\n

Using satellite remote sensing images, the scientists observed sea ice retreat almost immediately following atmospheric river storms and saw the retreat persisted for up to 10 days. Because of this melting and because the storms are becoming more common, atmospheric rivers are slowing down seasonal sea-ice recovery in the Arctic, the scientists said.<\/p>\n\n\n\n

\u201cWhen this kind of moisture transport happens in the Arctic, the effect is not only the amount of rain or snow that falls from it, but also the powerful melting effect on the ice,\u201d said Mingfang Ting, a professor at Lamont-Doherty Earth Observatory, Columbia University and a co-author. \u201cThis is important since we are losing Arctic sea ice fast in the past few decades that brought many unwanted consequences such as Arctic warming, erosion of Arctic coastlines, disturbance to global weather patterns and disruption to the Arctic communities and ecosystems.\u201d<\/p>\n\n\n\n

The loss of Arctic sea ice has broad implications, the scientists said. Open waters may enable new, more direct shipping routes but also trigger geopolitical concerns between countries. Additionally, freshwater melting into the salty ocean may impact oceanic circulations patterns that stabilize global temperatures.  <\/p>\n\n\n\n

\u201cThose factors make this study especially important from a science perspective, but also from social and security perspectives, said Laifang Li, assistant professor of meteorology and atmospheric science at Penn State and a co-author. \u201cSea ice melting has a big impact for the climate system and for society, and our study finds the Arctic is an open system and that climate change is way more complicated than temperature change alone can explain.\u201d<\/p>\n\n\n\n

Using large-ensemble climate models, the scientists determined that human-induced warming has increased the rate of atmospheric river storms in the Arctic. But they also found that one major mode of natural climate variabilities \u2014 the so-called Interdecadal Pacific Oscillation \u2014 also contribute to atmospheric river changes.<\/p>\n\n\n\n

\u201cThis study, together with other work that noted the presence of atmospheric rivers in the tropics, highlights that atmospheric rivers represent a global phenomenon,\u201d said Bin Guan, Earth systems scientist at the University of California, Los Angeles and Jet Propulsion Laboratory, California Institute of Technology. \u201cSince they were discovered relatively recently \u2014 in the 1990s, and even more recently in terms of recognizing their societal impacts \u2014 atmospheric rivers provide an opportunity for potentially coordinated research and applications globally, that is, with today\u2019s computational and technological capabilities.\u201d<\/p>\n\n\n\n