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Greenland's ice is melting faster than scientists thought

By Karen Graham     Jan 22, 2019 in Environment
Greenland's ice is melting faster than scientists previously thought - and this will likely lead to faster sea level rise -thanks to the continued, accelerating warming of the Earth's atmosphere, a new study has found.
Greenland’s southeast and northwest regions have long been the focus of scientists investigating sea level rise. These regions stream large iceberg-sized chunks of glacial ice into the Atlantic Ocean. The chunks float away, eventually melting and are a contributor to sea level rise.
A new study published Jan. 21 in the Proceedings of the National Academy of Sciences found that the largest sustained ice loss from early 2003 to mid-2013 came from Greenland’s southwest region, which is mostly devoid of large glaciers.
“Whatever this was, it couldn’t be explained by glaciers, because there aren’t many there,” said Michael Bevis, lead author of the paper, Ohio Eminent Scholar and a professor of geodynamics at Ohio State University. “It had to be the surface mass—the ice was melting inland from the coastline.”
Greenland's ice sheets are melting due to global warming  opening up new shipping routes and sp...
Greenland's ice sheets are melting due to global warming, opening up new shipping routes and sparking a race for resources
Steen Ulrik Johannessen, AFP/File
Bevis and his co-authors believe the melting is being caused by global warming, meaning that in Southwestern Greenland, growing rivers of water are now streaming into the ocean during the summer months. The researchers found that by 2012, ice loss in this region had accelerated at a rate nearly four times what it was in 2003, and it may have now reached a "tipping point."
"We knew we had one big problem with increasing rates of ice discharge by some large outlet glaciers," Bevis said, reports Science Daily. "But now we recognize a second serious problem: Increasingly, large amounts of ice mass are going to leave as melt-water, as rivers that flow into the sea."
It's too late for there to be no effect
This research provides fresh evidence of the dangers to vulnerable coastal areas, including New York and Miami in the U.S., and Shanghai, Bangladesh and various Pacific islands, most of them already being impacted with rising sea levels.
Rink Glacier in western Greenland  with a meltwater lake visible center. The gigantic solitary wave ...
Rink Glacier in western Greenland, with a meltwater lake visible center. The gigantic solitary wave dented the bedrock underneath the ice sheet.
NASA/JPL
“The only thing we can do is adapt and mitigate further global warming – it’s too late for there to be no effect,” Bevis said, according to The Guardian. “This is going to cause additional sea level rise. We are watching the ice sheet hit a tipping point.
Scientists have been monitoring the whole of the Greenland ice sheet since 2002. NASA and Germany joined forces to launch GRACE. GRACE stands for Gravity Recovery and Climate Experiment and involves twin satellites that measure ice loss across Greenland.
The data from the two GRACE satellites revealed that between 2002 and 2016, Greenland lost approximately 280 gigatons of ice per year, equivalent to 0.03 inches of sea level rise each year. Bevis's team used GRACE data and data from GPS stations scattered around Greenland's coast to identify changes in ice mass.
GRACE  twin satellites launched in March 2002  are making detailed measurements of Earth s gravity f...
GRACE, twin satellites launched in March 2002, are making detailed measurements of Earth's gravity field which will lead to discoveries about gravity and Earth's natural systems.
NASA/JPL - CalTech
This is when the researchers found the accelerated melting rate, and it was focused in southwest Greenland, a part of the island that previously hadn’t been known to be losing ice that rapidly.
The North Atlantic Oscillation
So, why is ice melting at an accelerated rate in Southwestern Greenland? Bevis and his research team blame this on a natural weather phenomenon - the North Atlantic Oscillation (NAO). Basically, the NAO describes the changes in pressure between these two regions and are classified as positive or negative influences which contribute to changes in the intensity and location of the North Atlantic jet stream.
Melting sea ice in the Arctic produces fresh water  slowing the circulation of denser salt water and...
Melting sea ice in the Arctic produces fresh water, slowing the circulation of denser salt water and thereby slowing warming currents
MARIO TAMA, GETTY IMAGES NORTH AMERICA/AFP/File
The study found the NAO was bringing warmer weather to western Greenland, along with clearer skies and increased solar radiation. Even though the NAO is a natural cycle that causes ice to melt under normal circumstances, when combined with man-made global warming, though, the effects are supercharged.
“These oscillations have been happening forever,” Bevis said. “So why only now are they causing this massive melt? It’s because the atmosphere is, at its baseline, warmer. The transient warming driven by the North Atlantic Oscillation was riding on top of more sustained, global warming.”
More about Greenland, southwest region, meltwater, Global warming, Sea level rise
 
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