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Another consequential year for the melting Arctic

  • This week, Arctic sea ice shrank to a summer low, joining 2017 and 2018 as the 10th lowest on record. But it’s the 16th consecutive year that ice extent has been minimal since satellite records began. The extent, thickness and volume of polar sea ice all continue to plummet.
  • Arctic temperatures have been high this summer, with some parts of the region experiencing unprecedented heat. In Greenland, temperatures rose to 36°F above normal in September. Canada’s Northwest Territories reached a record high in July, reaching the 90s. Sea temperatures also remained very high in many parts of the Arctic Ocean.
  • Concerns are growing about how polar warming is affecting atmospheric jet streams, intensifying devastating extreme weather events such as heatwaves, droughts and climate change around the world. storm.
  • A nearly ice-free Arctic could emerge by 2040, but scientists stress that it doesn’t have to happen. If humanity chooses to act now to significantly reduce greenhouse gas emissions, the trend of decreasing sea ice extent and amount could be reversed.

I went on an icebreaker in August Kingfish North of the Arctic Circle to Svalbard. We were invited to the bridge while cruising the nearly 80 fjords.th In parallel, I was glued to towering blue glacier walls, but confused by a map displayed on one of the ship’s screens. It showed that we were sailing across.

When I told this story to Walt Meier, senior research scientist at the National Snow and Ice Data Center, he wasn’t surprised. “Things are changing rapidly these days,” he said. So fast that even polar ice mapping can’t keep up.

The sun does not set and sea ice recedes The Spring/Summer 2022 Arctic Melting Season is now coming to an end as the days are rapidly shortening and the Far North is returning to complete winter darkness. 2018 was neither a record year nor a news story for low ice. was 10thtied with 2017 and 2018 — but it was yet another consequential thaw season.

Latest daily Arctic sea ice extent (JAXA AMSR2) for 2022 (thick red line). The mean sea ice extent for the 1980s, 1990s, 2000s, and 2010s is also shown as dashed lines. A thin white line for 2012 is shown. The annual minimum extent (2002 to 2021) is shown as colored scattered points relative to total sea ice extent. image Courtesy of Zachary Labe/Princeton/NOAA GFDL

It was the 16th straight year and the lowest since satellite tracking began in 1979. 2012 all-time lowsaid Zachary Rabe, a postdoctoral researcher at Princeton University in the National Oceanic and Atmospheric Administration’s (NOAA) Geophysical and Fluid Dynamics Laboratory. whole, Climate change is warming the Arctic Almost four times faster than the rest of the planetBut the melting is not even across the Arctic. Air and sea temperatures are the largest overall factors affecting sea ice, with wind and storms sometimes causing collateral damage.

Most of the globe had a scorching summer, with record heat waves. Hong Kong When India to many of Europeand the we— and above the world too. Temperatures in “a significant part of the Arctic” have been above the average for the past 30 years, Meier says. Unprecedented heat in Greenland during September, maximum 36 degrees Fahrenheit (20 degrees Celsius) higher than normal, which helped slightly prolong the melting phase. The lowest point of average sea ice is September 14th. This year it came on September 18th.

Northwest Territories of Canada, back in July Baked at extreme temperatures, skyrocketed in the 90s to new all-time highs. That record warmth has created countless melt ponds in the Beaufort sea ice. This is closely monitored by scientists because it retains a significant amount of “old” thick ice that is less likely to melt. Those molten ponds erode the ice from above.

newly published research of scientific report Temperatures in the North Barents Sea region (north of Norway and Russia north) from 1981 to 2020 were “exceptional” even for the Arctic, increasing five to seven times faster than global temperatures. I understand. about a year. Ice cubes in warm water melt faster than ice floating in cold water in a warm room, explains Meier.

Sea ice in the Beaufort Sea north of Canada and Alaska, the adjacent Chukchi Sea, and the Laptev Sea in Siberia began to melt abnormally earlier this year, in part due to rising sea temperatures.

The open ocean is blue and absorbs the sun’s rays, contributing to Arctic warming. Sea ice reflects sunlight back into space, helping to keep the Arctic cool. Image by Sharon Guynup.
Major seas, straits and bays of the Arctic region. Image courtesy of the National Snow and Ice Data Center.

This melting trend generated a localized feedback loop. Ice reflects at least 50% of solar radiation back into space. But ice-free blue oceans absorb about 90% of the sun’s heat, warming the oceans and melting more ice, Labe explains. August sea temperatures were the warmest ever in the Beaufort Sea. According to a recent study, 21st Century, Arctic Upper Mile Seawater temperature is 2.3 times higher than the global average.

Ocean currents flowing from the south into the Arctic also warm the water. Warm influxes from the Bering Strait, Pacific, and Atlantic could delay fall refreezing and hasten spring and summer ice loss.

Wind and storms also play a role, breaking and spreading the ice. Pushing an ice floe into a large body of water can cause it to melt. But along the northern coast of Greenland and the Canadian archipelago, where arctic winds push the ice onto land, the ice piles up to form thick ice that can withstand the summer heat.

Researchers have used whaling ship records, oceanographic data and logbooks to piece together sea ice information dating back to the 1800s. The data revealed year-to-year variability in weather. Labe describes it as “no more than a wavy line that rises and falls… until the 1980s, and then it declines.” Long-term trends “point to a clear, large-scale shift underway in the region,” he says.

of Overall downward trend The minimum extent of Arctic sea ice from 1979 to 2022 is 12.6% per decade Compared to the 1981-2010 average, about 30,300 square miles (78,500 square kilometers) per year, an area the size of Austria or South Carolina.

Satellite-era annual mean Arctic sea ice extent and volume changes (red) compared to reconstructions of Arctic sea ice extent dating back to the 1800s. Updated 8/21/2022. image Courtesy of Zachary Labe/Princeton/NOAA GFDL

on thin ice…

Since about 2005, the disappearance of Arctic sea ice, especially the September minimum, has dominated the news. But less attention has been paid to another important factor, ice thickness, which has decreased dramatically since the mid-1980s, says Meier. At that time, almost two-thirds of the Arctic Ocean was covered with multi-year ice. Today, about one-third of the multi-year ice remains.

The oldest ice, which survives several summers and melts and thickens during the frigid, dark winters, is solid, perhaps 12 feet thick in some places, durable, but virtually Disappeared, says Meier. “Currently, it’s about 5% of total ice cover, mainly along the northern coast of Greenland and the Canadian archipelago.”

First-year ice dominates, says Rabe, and is much thinner and more fragile.

He noted a unique and worrying event this year up to Highway 88 north.th Parallel, only 185 miles from the North Pole. In the past, this area was covered with thick ice floes and was frozen all year round. In recent years, satellite observations have revealed several patches of looser, less compact ice, but this summer there were “significant openings and areas of up to 38 by 38 square miles without ice.” “There were very few, if any,” he says.

Labe’s analysis puts this in perspective. “The story is basically that for the past 40 years, the ice has been thinning almost every month, almost all over the Arctic.” %) decreased.

Sea surface temperature (SST) in the Arctic Ocean, most of the North Atlantic and Pacific Oceans, and the surrounding waters of the Northern Hemisphere on August 23, 2022. Average conditions are found in the Bering and Norwegian Seas. Data and images courtesy of the University of Maine Climate Reanalyzer.

What starts at the North Pole…

Scientists say the Earth’s climate system is interconnected, with the rapidly warming Arctic Ocean, which is about the size of the 48 contiguous states of the United States, affecting the rest of the planet.

For example, some studies show that a warming Arctic climate may be changing where and how fast the atmospheric jet stream circles the northern hemisphere. take a deep south turn or hold slowly almost in placewhich can sometimes contribute to record-breaking weather patterns, etc. Abnormal weather. of polar vortexFor example, in the past it rotated mainly fast and tight around the polar regions, but became more wobbly and unstable, with occasional falls over the United States, Europe, or Asia, in bone-chilling cold. blow them away.

Overall, Meier said: [in terms of sea ice] is definitely a strong downtrend, even faster than what the model predicted. The Arctic is a vastly different environment than it used to be, and anyone who has lived or studied there will know. [the polar region]”

August monthly ice coverage from 1979 to 2022 shows a 10.1% decrease per decade. Image courtesy of the National Snow and Ice Data Center.

There is a lot of speculation about When will the Arctic Ocean experience its first largely ice-free summer?An early report from the United Nations Intergovernmental Panel on Climate Change predicted that this could happen by 2100. Probably mid-century decline by 2040.

But that particular milestone may be more important to the media than to scientists, Labe says. We’re already seeing it, and the more ice we lose, the bigger the impact.”

Sea ice loss and its rate “will depend on the emissions trajectory over the next 10, 20, 30 years,” says Meier. Human actions can bring about positive change.

Labe agrees. “Climate models show that we can reduce the chances of an ice-free Arctic by reducing greenhouse gas emissions. I would like to point out that it shows that it is not.”

Banner image: The open ocean with floating ice off the Arctic coast of Svalbard in August 2022. Image by Sharon Guynup.

Polar bears forage in the near-open ocean of the Arctic.Photo credit: Tim Ellis Visualhunt.com

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carbon emissions, climate, climate change, Climate change and extreme weather, climate science, environment, Abnormal weather, global environmental crisis, Global warming, green, greenhouse gas emissions, Impact of climate change, ocean and climate change, polar regions, research, satellite data, sea ​​ice, temperature, weather




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