Unparalleled warmth is changing the Arctic and affecting weather in US, Europe

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The Arctic is experiencing a multi-year stretch of unparalleled warmth “that is unlike any period on record,” according to the 2018 Arctic Report Card, a peer-reviewed report released Tuesday morning from the National Oceanic and Atmospheric Administration, an agency within the United States Department of Commerce.

The report states that human-caused climate change is transforming the Arctic, both physically through the reduction of sea ice, and biologically through reductions in wildlife populations and introduction of marine toxins and algae.
The report is yet another study from part of the US government indicating that climate change is real and having a profound impact, despite denials from the President and senior members of his Administration.

The year 2018 was the Arctic's second-warmest year on record behind 2016. The top five warmest years have all occurred since 2014.

Temperatures in the Arctic are warming more than twice as fast as the overall planet’s average temperature, with temperatures this year in the highest latitudes (above 60 degrees north) coming in 1.7 degrees Celsius (3.1 degrees Fahrenheit) above the 1981-2010 average. These were the second warmest (behind 2016) air temperatures ever recorded during the Arctic year, which runs from October through September to avoid splitting the winter season.
The five years since 2014 have been warmer than any other years in the historical record, which goes back to 1900. Although Arctic temperatures have been subject to wild swings back and forth through the decades due to natural variability, they have been consistently warmer than average since 2000 and at or near record since 2014, the report states.
“The changes we are witnessing in the Arctic are sufficiently rapid that they cannot be explained without considering our impacts on the chemistry of the atmosphere,” Thomas Mote, a research scientist at the University of Georgia who authored part of the report, told CNN in an email.
Mote expressed than any natural cycle or mechanism that would lead to the amount of warming and ice loss that has been observed would take much longer than the few years over which we have seen these drastic changes.

A vicious cycle

Since 2000, Arctic temperatures, shown in red, have been higher than the overall global temperature anomalies, shown in gray. In 2018 the Arctic was shown to be warming at an alarming rate, twice as fast as the average global temperature.

The rapid warming of the Arctic is known as “Arctic amplification,” which is due to multiple feedback loops that the report describes. Warmer temperatures lead to less ice and snow, which means less sunlight is reflected and more is absorbed by the darker oceans. This warms the ocean further, which in turn decreases the sea ice even more. The lack of sea ice and more ocean surface leads to additional cloudiness later in the fall season, which keeps the Arctic region warmer even later into the winter.
“What starts in the Arctic isn’t confined there,” Mote noted. “Changes in sea ice influence ocean currents and the jet stream in ways that can affect weather in lower latitudes, including the United States and Europe,” Mote said.
The report highlighted several of these events over the past year as an example of how Arctic warming can influence day-to-day weather.

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Sea Ice Continues To Decline
As you would expect with the trend of record warm temperatures, sea ice has seen dramatic declines over the past 20 years as well, with 2018 continuing that trend.
According to the 2018 Arctic Report Card, this year featured the second-lowest winter sea-ice extent — the amount of the Arctic Ocean that is covered with sea ice — since the satellite record began in 1979. The summer minimum sea ice was the sixth-lowest over the same time period.
While winter sea ice extents have decreased at a much slower rate compared to the ice extent during the summer, there has been a significant change to the ice pack during the winter.

Old ice -- ice that lasts through four or more melt seasons -- seen in 1985, left, and 2018, right.

The ice is much younger than it used to be. According to the report, fewer than 1% of Arctic ice is considered “oldest ice,” meaning it is at least four years old and has survived multiple melt seasons. Older ice tends to be thicker and more resilient to changes in temperature.
Since scientists began measuring the age of the ice in the mid-1980s, multi-year ice in the Arctic has decreased in size from 2.54 million square kilometers (roughly the size of Mexico and all of Central America combined) to 0.13 million square kilometers (roughly the size of Nicaragua in Central America) — a 95% reduction in a little over 30 years.
“Sea ice cover has transformed from a strong, thick pack in the 1980s to a more fragile, younger, thinner, and more mobile pack in recent years,” the report states, where “the thinner, younger ice is more vulnerable to melting out in the summer and has contributed to the decreasing trend in the minimum ice extent.”

The Arctic’s Warmest 5 Years on Record: 2014-Present

Sea ice along Greenland’s coast this yearCredit Joe MacGregor/NASA IceBridge

The Arctic has been warmer over the last five years than at any time since records began in 1900, and the region is warming at twice the rate as the rest of the planet, scientists said Tuesday.

The rising air temperatures are having profound effects on sea ice, and on life on land and in the ocean, the scientists said. The changes can be felt far beyond the region, especially since the changing Arctic climate may be influencing extreme weather events around the world.

Those assessments were part of the latest “Arctic Report Card,” issued by the National Oceanic and Atmospheric Administration, a federal agency, and presented Tuesday at a meeting of the American Geophysical Union in Washington.

“We’re seeing this continued increase of warmth pervading across the entire Arctic system,” said Emily Osborne, lead editor of the report and manager of NOAA’s Arctic Research Program. “That’s having implications for both ocean and terrestrial systems.”

The new edition of the report, which is published annually, does not present a radical break with past installments, but it shows that troublesome trends wrought by climate change are intensifying. Air temperatures in the Arctic in 2018 will be the second-warmest ever recorded, the report said, behind only 2016.

Susan M. Natali, an Arctic scientist at Woods Hole Research Center in Massachusetts who was not involved in the research, said the report was another warning going unheeded. “Every time you see a report, things get worse, and we’re still not taking any action,” she said. “It adds support that these changes are happening, that they are observable.”

The warmer Arctic air causes the jet stream to become “sluggish and unusually wavy,” the researchers said. That has possible connections to extreme weather events elsewhere on the globe, including last winter’s severe storms in the United States.

The jet steam normally acts as a kind of atmospheric spinning lassothat encircles and contains the cold air near the pole; a weaker, wavering jet stream can allow Arctic blasts to travel south in winterand can stall weather systems in the summer, among other effects.

The more rapid warming in the upper north, known as Arctic amplification, is tied to many factors, including the simple fact that snow and ice reflect a lot of sunlight, while open water, which is darker, absorbs more heat. As sea ice melts, less ice and more open water create a “feedback loop” of more melting that leads to progressively less ice and more open water.

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