Navigation Links
Extreme melting on Greenland ice sheet, reports CCNY team

The Greenland ice sheet can experience extreme melting even when temperatures don't hit record highs, according to a new analysis by Dr. Marco Tedesco, assistant professor in the Department of Earth and Atmospheric Sciences at The City College of New York. His findings suggest that glaciers could undergo a self-amplifying cycle of melting and warming that would be difficult to halt.

"We are finding that even if you don't have record-breaking highs, as long as warm temperatures persist you can get record-breaking melting because of positive feedback mechanisms," said Professor Tedesco, who directs CCNY's Cryospheric Processes Laboratory and also serves on CUNY Graduate Center doctoral faculty.

Professor Tedesco and his team collected data for the analysis this past summer during a four-week expedition to the Jakobshavn Isbr glacier in western Greenland. Their arrival preceded the onset of the melt season.

Combining data gathered on the ground with microwave satellite recordings and the output from a model of the ice sheet, he and graduate student Patrick Alexander found a near-record loss of snow and ice this year. The extensive melting continued even without last year's record highs.

The team recorded data on air temperatures, wind speed, exposed ice and its movement, the emergence of streams and lakes of melt water on the surface, and the water's eventual draining away beneath the glacier. This lost melt water can accelerate the ice sheet's slide toward the sea where it calves new icebergs. Eventually, melt water reaches the ocean, contributing to the rising sea levels associated with long-term climate change.

The model showed that melting between June and August was well above the average for 1979 to 2010. In fact, melting in 2011 was the third most extensive since 1979, lagging behind only 2010 and 2007. The "mass balance", or amount of snow gained minus the snow and ice that melted away, ended up tying last year's record values.

Temperatures and an albedo feedback mechanism accounted for the record losses, Professor Tedesco explained. "Albedo" describes the amount of solar energy absorbed by the surface (e.g. snow, slush, or patches of exposed ice). A white blanket of snow reflects much of the sun's energy and thus has a high albedo. Bare ice being darker and absorbing more light and energy has a lower albedo.

But absorbing more energy from the sun also means that darker patches warm up faster, just like the blacktop of a road in the summer. The more they warm, the faster they melt.

And a year that follows one with record high temperatures can have more dark ice just below the surface, ready to warm and melt as soon as temperatures begin to rise. This also explains why more ice sheet melting can occur even though temperatures did not break records.

Professor Tedesco likens the melting process to a speeding steam locomotive. Higher temperatures act like coal shoveled into the boiler, increasing the pace of melting. In this scenario, "lower albedo is a downhill slope," he says. The darker surfaces collect more heat. In this situation, even without more coal shoveled into the boiler, as a train heads downhill, it gains speed. In other words, melting accelerates.

Only new falling snow puts the brakes on the process, covering the darker ice in a reflective blanket, Professor Tedesco says. The model showed that this year's snowfall couldn't compensate for melting in previous years. "The process never slowed down as much as it had in the past," he explained. "The brakes engaged only every now and again."

The team's observations indicate that the process was not limited to the glacier they visited; it is a large-scale effect. "It's a sign that not only do albedo and other variables play a role in acceleration of melting, but that this acceleration is happening in many places all over Greenland," he cautioned. "We are currently trying to understand if this is a trend or will become one. This will help us to improve models projecting future melting scenarios and predict how they might evolve."

Additional expedition team members included Christine Foreman of Montana State University, and Ian Willis and Alison Banwell of the Scott Polar Research Institute, Cambridge, UK.

Professor Tedesco and his team provide their preliminary results on the Cryospheric Processes Laboratory webpage. They will will be presenting further results at the American Geophysical Union Society (AGU) meeting in San Francisco on December 5 at 9 a.m. and December 6 at 11:35 a.m.


Contact: Jessa Netting
City College of New York

Related biology news :

1. Vegetation hardly affected by extreme flood events
2. Extreme nature helps scientists design nano materials
3. Extreme weather postpones the flowering time of plants
4. Geoscientists discuss sea level rise, extreme storm events and more
5. Genome projects launched for three extreme-environment animals
6. Treatment for extreme nausea, vomiting during pregnancy
7. Scientists track chemical changes in cells as they endure extreme conditions
8. Extreme genes shed light on origins of photosynthesis
9. First metallic nanoparticles resistant to extreme heat
10. Extremes of sleep related to increased fat around organs
11. Road salt and cars produce extreme water contamination in Frenchmans Bay, UTSC research reveals
Post Your Comments:
(Date:11/4/2015)... York , November 4, 2015 ... a new market report published by Transparency Market Research "Home ... Growth, Trends and Forecast 2015 - 2022", the global home ... US$ 30.3 bn by 2022. The market is estimated ... forecast period from 2015 to 2022. Rising security needs ...
(Date:10/29/2015)... Minn. , Oct. 29, 2015   MedNet ... supports the entire spectrum of clinical research, is pleased ... Minnesota High Tech Association (MHTA) as one of only ... in the "Software – Small and Growing" category. The Tekne ... individuals who have shown superior technology innovation and leadership. ...
(Date:10/29/2015)... Va. , Oct. 29, 2015 Daon, ... today that it has released a new version of ... customers in North America have ... IdentityX v4.0 also includes a FIDO UAF certified ... are already preparing to activate FIDO features. These customers ...
Breaking Biology News(10 mins):
(Date:12/1/2015)... Calif. , Dec. 1, 2015 ... Transformational Health program. This program addresses ways companies ... of change. ... Logo - ... aspect of healthcare, as well as the disrupting ...
(Date:12/1/2015)... Dec. 01, 2015 ... of the "2016 Europe Cell Surface ... Technologies, Competitive Strategies, Opportunities for Suppliers--France, Germany, ... offering. --> ) has ... Europe Cell Surface Markers: Country Volume and ...
(Date:12/1/2015)... ... December 01, 2015 , ... RURO, Inc., ... selling system laboratory animal colony management software solution, ezColony®, is now available as ... IT resources., , Many organizations are moving to cloud-hosting ...
(Date:12/1/2015)... 1, 2015 Cepheid (Nasdaq: CPHD ) ... the Piper Jaffray Healthcare Conference in New ... is reaffirming its outlook for the fourth quarter of ... to discussing longer term business model expectations. ...  "We continue to be the fastest growing company of ...
Breaking Biology Technology: