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Study foresees big changes in Greenland ice melt

Iceberg calving to be less of a factor as glaciers retreat

greenlandponds_ali_2010185

Melt ponds of the surface of the Greenland ice cap. Photo courtesy NASA Earth Observatory. Visit this NASA page for more information on Greenland surface melting.

By Summit Voice

FRISCO — Greenland’s melting ice cap will continue to contribute to sea level rise, but iceberg calving will become less of a factor as glaciers retreat inland. Instead, surface melting and runoff will account for more than 80 percent of ice cap’s contribution to sea level rise, according to new research from the Vrije Universiteit Brussel.

Changes in its total mass are governed by two main processes — fluctuations in melting and snowfall on its surface, and changes to the number of icebergs released from a large number of outlet glaciers into the ocean. The ice loss from the ice sheet has been increasing during the last decade, with half of it attributed to changes in surface conditions with the remainder due to increased iceberg calving.

The research team from the Vrije Universiteit Brussel, funded by ice2sea, a European Union project, tackled the question of how both processes will evolve and interact in the future with a new computer model to help accurately project future ice sheet evolution. The study was published last week in the Journal of Glaciology.

“Our research has shown that the balance between the two most important mass loss processes will change considerably in the future so that changes in iceberg calving only account for a small percentage of the sea-level contribution after 200 years with the large remainder due to changes in surface conditions,” said lead author Dr. Heiko Goelzer.

“This scenario is no reason to be complacent,” said British Antarctic Survey Professor David Vaughan, coordinator of the ice2sea program. “The reason the significance of calving glaciers reduces compared to surface melting is, so much ice will be lost in coming decades that many glaciers currently sitting in fjords will retreat inland to where they are no longer affected by warming seas around Greenland.”

If Greenland’s ice melted all at once, it would raise sea level by more than 20 feet, but the study calculated that, under an average global warming scenario, enough ice will melt to raise sea level by about 7 centimeters in the next 100 years, and by 21 centimeters after 200 years.

But when glaciers retreat farther inland, they won’t be able to discharge icebergs into the sea. In a couple of hundred years, calving  may only account for between 6 percent and 18 percent of the Greenland ice cap’s sea-level contribution. This is important, because variations in outlet glacier dynamics have often been suspected to have the potential for very large sea-level contributions.

“Our research has shown that the balance between the two most important mass loss processes will change considerably in the future so that changes in iceberg calving only account for a small percentage of the sea-level contribution after 200 years with the large remainder due to changes in surface conditions,” said lead author Dr. Heiko Goelzer.

“This scenario is no reason to be complacent,” said British Antarctic Survey Professor David Vaughan, coordinator of the ice2sea program. “The reason the significance of calving glaciers reduces compared to surface melting is, so much ice will be lost in coming decades that many glaciers currently sitting in fjords will retreat inland to where they are no longer affected by warming seas around Greenland

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  1. […] Study foresees big changes in Greenland ice melt […]

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