New studies investigating the ice found at the planet’s polar regions are reporting that a precarious situation appears to be unfolding at the ends of the Earth, with the increased melting of both sea and glacial ice in the Arctic Ocean, Greenland, and even the supposedly-stable glaciers of East Antarctica.
NOAA’s 2018 Arctic Report Card, a report on the state of the environment in the far north that has been issued annually since 2006, outlines the drastic changes in the region that were observed over the course of the year, including the continued trend of the Arctic warming "at twice the rate relative to the rest of the globe"; increases in ocean temperatures are facilitating an expansion of toxic algal blooms; herd populations of caribou and wild reindeer have declined by nearly 50 percent over the last twenty years; and a massive decrease in older sea ice has been recorded.
Older Arctic sea ice — ice that has lasted for five years or more — is key to the stability of the overall ice pack, as "older ice tends to be thicker and is thus more resilient to changes in atmospheric and oceanic heat content compared to younger, thinner ice," according to the report. But that valuable ice has seen a sharp decline in recent decades, having receded by 95 percent since 1985.
Since older ice tends to be thicker — it’s had a longer amount of time to accumulate more ice — that volume also makes it harder to melt, allowing newer ice to not only form, but also to give that new ice a chance to last past the summer melt; without the thicker ice to back it up, new ice might rapidly form over the course of the winter, but it also melts faster when temperatures rebound over the summer.
This loss in thickness also means that sea ice in the Arctic is not only receding in terms of surface area, but also in overall volume, meaning the Arctic has been losing more ice than what we’ve been aware of. The University of Washington’s Axel Schweiger sets out the equation: "We’ve lost about half of the extent, we’ve lost half of the thickness, and if you multiply these two things, we’ve lost 75 percent of the September sea ice." Schweiger runs the university’s Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS), and according to PIOMAS’s data, the Arctic Ocean has lost over 10 trillion tons of ice since 1979, dropping from 15 trillion tons in September of that year, to a mere 4.66 trillion tons as of September 2018.
Greenland is also experiencing an increase in ice melt over the past two decades that hasn’t been seen in at least 350 years, and is an event that is probably without precedent in the past eight millennia, according to a new study from researchers at Rowan University in Glassboro. Using ice cores that represent 350 years of history from Greenland’s glaciers, the study finds that the meltwater runoff from the island’s ice was 33 percent higher than the twentieth-century average over the past twenty years, and 50 percent higher than in the pre-industrial era.
"The melting is not just increasing — it’s accelerating," says the study’s lead author Luke Trusel, a glaciologist with Rowan.
Researchers have also found that the glaciers in East Antarctica are experiencing a more pronounced melt than what was previously anticipated, with ice streams along the coast thinning out and increasing their speed. Long thought to be more stable than the extensive ice shelves on the western portion of the continent, East Antarctica’s ice sheet is the world’s largest concentration of ice; if it were to melt entirely, it would raise ocean levels worldwide by 28 meters (92 feet), four times more than if all of the ice covering Greenland were to melt.
Previously, Antarctica’s Totten Glacier was thought to be the only glacier in the east that was experiencing any significant melt, due to warm ocean water eroding it where it meets the sea, but new satellite data shows that other glaciers in the region are thinning and increasing their flow speed as well. Found in Vincennes Bay, the Underwood, Bond, Adams, and Vanderford glaciers are the hardest hit, with their seasonal elevations dropping at a rate five times faster than what was recorded ten years ago, making them now 3 meters (10 feet) lower than they were in 2008.
"They’ve also sped up about 3% from their 2008 velocity, which sounds small but is significant enough to change the flux coming out of those glaciers because they are very deep," explains Dr. Catherine Walker, from NASA’s Goddard Space Flight Center.
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