Using satellite imagery, NASA was able to see how quickly a series of glaciers have been melting since 1972. The short six second time-lapses show how glaciers in Alaska, Greenland and Antarctica are retreating, adding to the problem of rising sea levels. Glaciologist Mark Fahnestock of the University of Alaska Fairbanks said: “We now have this long, detailed record that allows us to look at what’s happened in Alaska.
“When you play these movies, you get a sense of how dynamic these systems are and how unsteady the ice flow is.”
Some of the time-lapses show lakes beginning to form at the bottom of the glaciers, others show how as the land begins to thaw, mountains begin to crumble, creating tremendous landslides.
One such glacier, the Columbia Glacier, found in Alaska, appeared to be stable when the Landsat satellite launched in 1972, but years of climate change shows how it has retreated by 12.4 miles (20 kilometres) in 2019.
Michalea King of Ohio State University analysed data of Greenland’s glaciers dating back to 1980 and found that on average, they retreated an average of about three miles (5km) as of 2018.
Ms King said: “These glaciers are calving more ice into the ocean than they were in the past.
“There is a very clear relationship between the retreat and increasing ice mass losses from these glaciers during the 1985-through-present record.”
James Lea of the University of Liverpool analysed how the melting glaciers formed lakes at the base of the mountains and was stunned at the results, stating that scientists were not expecting this much meltwater for another 30 years.
He said: “We looked at how many lakes there are per year across the ice sheet and found an increasing trend over the last 20 years: a 27 percent increase in lakes.
“We’re also getting more and more lakes at higher elevations – areas that we weren’t expecting to see lakes in until 2050 or 2060.”
What is most concerning, according to the scientists, is that the increased meltwater could accelerate the melting glaciers.
As they form, they begin to “punch” through the ice at the bottom of the glacier, exacerbating the retreat.
Devon Dunmire of the University of Colorado, Boulder, said: “Not much is known about distribution and quantity of these subsurface lakes, but this water appears to be prevalent on the ice shelf near the Antarctic peninsula and it’s an important component to understand because meltwater has been shown to destabilise ice shelves.”
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As it stands, sea levels are rising at about 8mm a year due to melting ice, and while that does not seem like much, the implications for future generations could be huge.
Between 1993 and 2014, sea levels rose by 66mm – or roughly 3mm per year.
If it continues at the current rate, or gets faster, it could mean coastal cities such as New York could be submerged by the end of the century.
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