Greenland Ice Background
Greenland is situated in the Atlantic Ocean to the northeast of Canada. It has stunning fjords on its
rocky coast formed by moving glaciers, and a dense icecap up to 2 km thick that covers much of the
island – pressing down the land beneath and lowering its elevation. Now, scientists at the University
of Miami say Greenland’s ice is melting so quickly that the land underneath is rising at an accelerated pace.
Uplift of Up To Two Inches Per Year by 2025!
According to the study, some coastal areas are going up by nearly one inch per year and if current trends
continue, that number could accelerate to as much as two inches per year by 2025, explains Tim Dixon,
professor of geophysics at the University of Miami Rosenstiel School of Marine and Atmospheric Science
(RSMAS) and principal investigator of the study.
“It’s been known for several years that climate change is contributing to the melting of Greenland’s ice sheet,”
Dixon says. “What’s surprising, and a bit worrisome, is that the ice is melting so fast that we can actually see
the land uplift in response,” he says. “Even more surprising, the rise seems to be accelerating, implying that
melting is accelerating.”
The Same Process Affects Other Areas of Melting
Dixon and his collaborators share their findings in a new study titled “Accelerating uplift in the North
Atlantic region as an indicator of ice loss,” now published as an advance online publication by Nature
Geoscience. The idea behind the study is that if Greenland is losing its ice cover, the resulting loss of
weight causes the rocky surface beneath to rise. The same process is affecting the islands of Iceland and
Svalbard, which also have ice caps, explains Shimon Wdowinski, research associate professor in the Univeristy
of Miami RSMAS, and co-author of the study.
“During ice ages and in times of ice accumulation, the ice suppresses the land,” Wdowinski says. “When the ice
melts, the land rebounds upwards,” he says. “Our study is consistent with a number of global warming indicators,
confirming that ice melt and sea level rise are real and becoming significant.”
GPS Data Stations on Bedrock
Using specialized global positioning system (GPS) receivers stationed on the rocky shores of Greenland, the
scientists looked at data from 1995 onward. The raw GPS data were analyzed for high accuracy position information,
as well as the vertical velocity and acceleration of each GPS site.
The measurements are restricted to places where rock is exposed, limiting the study to coastal areas. However,
previous data indicate that ice in Greenland’s interior is in approximate balance: yearly losses from ice melting
and flowing toward the coast are balanced by new snow accumulation, which gradually turns to ice. Most ice loss
occurs at the warmer coast, by melting and iceberg calving and where the GPS data are most sensitive to changes.
In western Greenland, the uplift seems to have started in the late 1990’s.
Largest Contributor to Global Sea Level Rise?
Melting of Greenland’s ice contributes to global sea level rise. If the acceleration of uplift and the implied acceleration
of melting continues, Greenland could soon become the largest contributor to global sea level rise, explains
Yan Jiang, Ph.D. candidate at the University of Miami RSMAS.
“Greenland’s ice melt is very important because it has a big impact on global sea level rise,” Jiang says. “We hope that
our work reaches the general public and that this information is considered by policy makers.”
The team plans to continue its studies, looking at additional GPS stations in sensitive coastal areas, where ice loss is
believed to be highest.
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| Cartoon showing the mass balance of the water cycle with respect to polar ice, sea level and crustal uplift. Modified after USGCRP.gov. |
| Climate Change in the News |
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