Arctic summer could be practically sea ice-free by 2030
The first recorded summer in which virtually all floating sea ice in the Arctic melts could occur as early as the 2030s, according to a study. new scientific study — about a decade earlier than researchers had previously predicted.
The peer-reviewed findings, published Tuesday, also show that this climate change milestone could become a reality even if countries manage to curb greenhouse gas emissions more decisively than they currently do. Previous projections had suggested that stronger measures to slow global warming could be enough to preserve summer ice. The latest research suggests that, when it comes to Arctic sea ice, only steep, sharp reductions in emissions can reverse the effects of ongoing warming.
“We are on the verge of losing Arctic sea ice cover in summer very quickly, really regardless of what we do,” said Dirk Notz, a climate scientist at the University of Hamburg in Germany and one of five authors of the new paper. study. “We have now waited too long to do anything about climate change to protect the remaining ice.”
As sea ice has receded in recent decades, communities, ecosystems and economies around the world are grappling with the consequences. But the effects extend far beyond the region.
Sea ice reflects solar radiation back into space, so the less ice there is, the faster the Arctic warms. As a result, the Greenland ice sheet is melting faster, causing global sea levels to rise.
The temperature difference between the North Pole and the equator also affects storm tracks and wind speed in mid-latitudes, meaning that the warming of the North Pole could affect weather events such as extreme rainfall and heat waves in temperate parts of North America, Europe and Asia.
In the past four decades, the far north has already done so been warming up four times as fast as the world average, a phenomenon scientists call Arctic strengthening.
“Our result suggests that the Arctic strengthening will come faster and stronger,” said Seung-Ki Min, a climate scientist at South Korea’s Pohang University of Science and Technology and another author of the new paper. “That means the related effects will come faster as well.”
Over the course of each year, the surface water of the Arctic Ocean freezes and melts with the seasons. The amount of ice grows in winter, peaks around March, and then decreases to an annual minimum, usually in September.
September’s lows have been moving down since continuous satellite measurements began in 1979, leading researchers to try to predict when the ocean could experience its first summer where all floating ice effectively melts.
This doesn’t mean there wouldn’t be any ice on the water – patches of ice are expected to remain in certain corners of the Arctic for some time to come. Instead, the threshold scientists use is 1 million square miles of ice, or about 386,000 square miles. This is less than 15 percent of the Arctic’s seasonal minimum ice cover in the late 1970s.
Looking at both satellite measurements of ice cover and computer models of global climate, researchers have predicted that September’s ice will likely dip below this level for the first time before 2050. But the exact timing has been difficult to predict, in part because the computer models generally underestimate the sea ice slumps that satellites have detected.
The authors of the latest study, which was published in the journal Nature Communications, explained this problem by first modifying the climate models to better match the satellite observations. They then used the modified models to project future changes in sea ice under four possible scenarios for greenhouse gas emissions over the coming decades.
Under three of these scenarios, which represent moderate to strong increases in emissions, September’s ice will fall below the critical threshold for the first time as early as the 2030s, about a decade earlier than previously estimated.
But the study also found roughly similar timing under the fourth scenario, in which humanity will stop pumping additional heat-trapping gases into the atmosphere around 2070, something the nations’ policies are not on track to achieve. Previous research had suggested that September could remain abundantly frosty in this scenario.
The Arctic Ocean’s first unfrozen September, if and when it comes, will be an important scientific benchmark, but it won’t be anything of a turning point, said Mark C. Serreze, the director of the National Snow and Ice Data Center at the Arctic Ocean. University of Colorado Boulder. The Arctic began to transform into a bluer ocean decades ago, triggering massive changes polar bear populations, shipping lanes, access to natural resources And geopolitics.
“It’s already happening,” said Dr. Serreze, who was not involved in the new investigation. “And as the Arctic continues to lose its ice, those effects will grow and grow and grow.”