Across the icy dome that crowns the Earth, rising temperatures are turning the tundra greener and more lush. Beavers are expanding their range. Garbage from passing ships is fouling the shores. Wildfires are scorching the once permanently frozen lands of Siberia.
Such is the picture that scientists painted in their latest assessment of the Arctic, which is heating up more than twice as quickly as the rest of the globe. This warming has propelled a variety of disruptions that make the polar region a potential harbinger for what people at lower latitudes might someday experience as a result of human-induced climate change.
“The vulnerabilities in the Arctic are more noticeable,” said Matthew L. Druckenmiller of the University of Colorado Boulder’s National Snow and Ice Data Center, who was an editor of the new assessment. “But these are similar vulnerabilities that we’re going to see unfold for our entire planet in the decades to come.”
While this year’s Arctic Report Card does not recount “blockbuster,” record-breaking changes in the region’s climate, it nonetheless shows “consistent, alarming and undeniable” trends toward drastically different conditions there, said Richard W. Spinrad, the administrator of the National Oceanic and Atmospheric Administration, which produces the annual health check.
Snow cover and sea ice continued to be below average. This April, the volume of sea ice in the Arctic Ocean was the lowest since records started being kept in 2010, the assessment’s authors reported. Sea ice helps slow warming by reflecting most of the sunlight that strikes it.
Arctic sea ice this year was also thinner than in recent years, the researchers said. Thinning ice has driven growth in shipping traffic, and with it a rise in garbage and noise pollution that could be affecting the movement of marine mammals.
In the Eurasian Arctic, snow cover this June was the third lowest since records began in 1967, the scientists said. This has increased the potential for wildfires such as the ones that have ravaged Siberia the past few summers.
The Greenland ice sheet, which covers about 650,000 square miles and is already one of the fastest-melting ice chunks on Earth, experienced three “extreme melt” episodes this summer, the researchers reported. At the sheet’s frigid summit in August, it rained for what is believed to be the first time.
More than 110 scientists from 12 nations contributed to the latest Arctic Report Card, which was presented on Tuesday in New Orleans at the annual meeting of the American Geophysical Union.
Changing conditions at the top of the world can have cascading effects farther afield, said Gabriel J. Wolken, a research scientist at the University of Alaska Fairbanks and the lead author of the report card’s chapter on glaciers and permafrost.
Melting glaciers can cause sea levels to rise worldwide. And the Arctic’s frozen soils store large amounts of carbon. As permafrost thaws, this carbon could be released into the air, accelerating global warming.
That is on top of the increased likelihood of landslides that glacial retreat and thawing permafrost bring about within the Arctic. In Alaska a few years ago, a slope failure at the edge of a glacier sent millions of tons of rock into a bay, producing one of the tallest documented tsunamis.
The authors of this year’s report card emphasized that the Arctic region’s residents were directly experiencing the impacts from all of these shifts. In recent years, the researchers have begun seeking the input of local Indigenous communities in producing the assessment.
“These changes are not abstract,” said Richard L. Thoman, a climate specialist at the University of Alaska and another editor of the report. “It’s not just about polar bears. It’s about actual human beings, members of the world community that are being impacted now.”
Source : Nytimes
