Scientists: Greenland’s land rises as ice melts

Sunday, December 11th 2011. | Science News

A new study released Friday finds that Greenland has risen in recent years as the rate of ice melting has increased, a startling revelation that scientists attribute to global warming.

Speaking at a conference on Friday, a team of scientists from Ohio State University said a network of 50 GPS stations measured the uplift as the ice loss, noting that the rate of ice loss has accelerated in southern Greenland by 100 billion tons. The study was lead by Ohio State University researcher Michael Bevis.

Greenland’s land rises as ice meltsMr. Bevis noted that an unusually hot melting season in 2010 accelerated ice loss in southern Greenland by 100 billion tons, which led to large portions of the island’s bedrock rising an additional quarter of an inch. The discovery was noted by the team in a paper released ahead of the conclusion of a key global climate change conference in Durban, South Africa.

“Pulses of extra melting and uplift imply that we’ll experience pulses of extra sea level rise,” said Mr. Bevis. “The process is not really a steady process.”

Mr. Belvis said the only explanation for the strange uplift is the rate of ice melt caused, in part, by global warming. The melting and the resulting rise in sea level is one of the hallmarks of global warming, which has force researchers to resort to using some novel methods to overcome different seasonal and regional signals that obstruct their ability to measure the effect of rising temperatures.

“Really, there is no other explanation. The uplift anomaly correlates with maps of the 2010 melting day anomaly,” Mr. Bevis said. “In locations where there were many extra days of melting in 2010, the uplift anomaly is highest.”

The team of scientists noted that a melting day “anomaly” refers to the number of extra melting days – that is, days that were warm enough to melt ice – relative to the average number of melting days per year over several decades. The occurrence of “melting day anomalies” have increased in recent years as global emissions continue to increase.

Speaking on Friday, Mr. Bevis noted that in 2010, the southern half of Greenland lost an extra 100 billion tons of ice under conditions that scientists would consider anomalously warm.

Previous studies have recorded measurements indicating that as that ice melted away, the bedrock beneath it rose. The amount of uplift differed from station to station, depending on how close the station was to regions where ice loss was greatest. Southern Greenland stations that were very close to zones of heavy ice loss rose one inch every five months. Stations that were located far away typically rose at least less than half and inch during the course of the 2010 melting season. The weight of ice sheets push down on the bedrock it rests on, scientists noted, and as the ice sheets lose mass, the bedrock rises. Scientists said the process is known as Glacial Isostatic Adjustment, adding that it has been happening since the planet came out of an ice age around 17,000 years ago.

The team that led the study said that is was conducted by using high-precision global positioning system (GPS) data that measure the vertical motion of the rocky margins around Greenland, Iceland and other regions of the island.

The study comes just two weeks after a series of global climate change meetings in Durban, South Africa. The meeting was set to concluded on Friday. The meetings have pitted the U.S. against emerging powers China and India over whether to hold each other accountable for greenhouse-gas emissions. The European Union has indicated that the world’s three biggest polluters, China, India and the United States, have been slowing down the pace of negotiations on a roadmap to a future agreement.

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