A warming climate is causing a decrease in sea ice in the Arctic Ocean, where the loss of sea ice has important ecological, economic and climatic impacts. In addition to this long-term change due to climate change are the weather events that affect the ice from week to week.
The strongest arctic cyclone ever observed poleward of 70 degrees north latitude struck in January 2022 northeast of Greenland. A new analysis led by the University of Washington shows that while weather forecasts accurately predicted the storm, ice models seriously underestimated its impact on the region’s sea ice.
The study, published in October in Journal of Geophysical Research-Atmospheressuggests that existing models underestimate the impact of large waves on ice floes in the Arctic Ocean.
“Sea ice loss over six days was the largest change we could find in historical observations since 1979, and the area of ice lost was 30 percent greater than the previous record,” said lead author Ed Blanchard- Wrigglesworth, a research assistant. professor of atmospheric sciences at UW. “The ice models predicted some loss, but only about half of what we saw in the real world.”
Accurate sea ice forecasts are important safety tools for northern communities, mariners and others operating in Arctic waters. Forecast accuracy in the Arctic Ocean also has wider effects.
“The ability to forecast weather in the Arctic affects the ability to forecast weather elsewhere,” Blanchard-Wrigglesworth said.
The January 2022 cyclone had its lowest predicted center of pressure since satellite records began in 1979, above 70 degrees north. It was an extreme version of a typical winter storm. Climate change does not appear to be responsible for the cyclone: Researchers have found no trend in the strength of intense Arctic cyclones since 1979, and sea ice extent was close to the historical normal for that region before the storm hit.
During the storm, record winds howled across the Arctic Ocean. The waves grew to 8 meters (26 feet) high in open water and remained surprisingly strong as they traveled through the sea ice. The ice rose 2 meters (6 feet) up and down near the edge of the ice pack, and NASA’s ICESat-2 satellite shows waves reached up to 100 kilometers (60 miles) toward the center of the ice pack.
Six days after the storm hit, sea ice has thinned significantly in affected waters north of Norway and Russia, in places losing more than half a meter (about 1.5 feet) of thickness.
“It was a monster storm, and the sea ice got hammered. And the sea ice models didn’t predict this loss, which suggests there are ways we could improve the model physics,” said second author Melinda Webster, assistant research professor at the University of Alaska Fairbanks. She begins a research position in the new year at the UW Applied Physics Laboratory.
The new analysis shows that atmospheric heat from the storm had little effect, meaning another mechanism was to blame for the ice loss. Possibilities, Blanchard-Wrigglesworth suggests, include sea ice that was thinner before the storm hit than models had predicted; that the storm surges broke up the ice floes with more force than the models predicted because they penetrated deep into the ice pack; or that the waves stirred up deeper, warmer water and brought it into contact with the sea ice, melting the ice below.
The unexpected loss of ice despite an accurate storm forecast suggests this is an area where the models could improve. The researchers hope to monitor future storms to identify exactly what led to the dramatic loss of sea ice, potentially by placing sensors in the path of a future approaching storm.
Although this storm does not appear to be linked to climate change, an increasing amount of open water as sea ice melts allows for larger waves that erode Arctic coastlines. These waves, the researchers said, could also affect the remaining ice pack.
“Going forward, it’s something to keep in mind, that these extreme events could produce these episodes of huge sea ice loss,” Blanchard-Wrigglesworth said.
Other co-authors are Linette Boisvert of NASA, Chelsea Parker of NASA and the University of Maryland, and Christopher Horvat of the University of Auckland and Brown University. The research was funded by NASA, the US Navy’s Office of Naval Research and Schmidt Futures.
Video: https://youtu.be/p44XJ6rAP08
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Materials provided by University of Washington. Originally written by Hannah Hickey. Note: Content may be edited for style and length.