Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Melt down

01.11.2001


Half a century of thinning ice leaves Greenland’s future looking wet.


Thinning on top: the Greenland ice sheet is in retreat.
© SPL


Satellites and planes have been measuring the ice sheet’s thickness for the past decade.
© Geoatlas



There is new evidence that the Greenland ice pack is in retreat. The finding may be a foretaste of still more rapid melting, and in turn, rising sea levels.

The ice sheet over northwest Greenland has thinned by 10-15 cm a year over the past 40 years, two scientists calculate1. The trend indicates "a significant long-term thinning", says one, Niels Reeh, of the Technical University of Denmark.


The sheet is more than 3 km thick in some places. It is the world’s second-largest ice mass after Antarctica. Reeh and Stan Paterson, of Paterson Geophysics in Heriot Bay, British Columbia, Canada, compared historical and modern data. This revealed that thinning has been much more pronounced in northwestern Greenland. In the east, there has been little change.

The reason for the east-west difference is not yet clear. Climate changes that occurred hundreds or even thousands of years ago may have altered the physical properties of the ice sheet. Or, like southern Greenland, the northern sheet may be sliding from east to west. Alternatively, the difference may reflect more recent variations in snowfall and temperatures.

Paterson is convinced that the thinning is due to the Earth’s recent temperature rise: "I’d stick my neck out and say that it’s an effect of global warming." Taken with signs of shrinking sea ice over the North Pole and melting at Greenland’s coast, "it’s just one more thread in the story", he says.

"The general consensus is that the central part of the ice sheet is in balance," cautions climate researcher Ellen Mosley-Thompson, of Ohio State University in Columbus. "But if the thinning is real, and if it were to continue for decades to centuries, that would translate into changes in the ice sheet."

Others are less sure. "Up to today, there’s been no convincing sign of Greenland growing or shrinking overall," says Philippe Huybrechts of the Free University of Brussels in Belgium. In fact, Greenland has bucked climate trends, ending the twentieth century slightly cooler than it began, he adds.

Whatever’s happening now, "all climate models show Greenland warming over the coming century", says Huybrechts. This will cause a rise in sea level of several centimetres. "If the climate were to warm, Greenland will be in bad shape, that’s for sure," Huybrechts says.

Seeking long-term trends

Several decades of measurements are needed to understand ice sheets. Short-term changes in temperature and snowfall can obscure underlying trends. For the past ten years, satellites and planes have been taking accurate measurements of the ice sheet’s thickness. But there are few good records from before 1990.

The researchers also drew on information gathered by the British North Greenland Expedition of 1954-55. This joint project saw scientists - including Paterson - and the British Navy journey 1,200 km across the top of Greenland, measuring altitude at 300 points along the way.

"The only way in was on RAF flying boats to a lake that was only unfrozen in August," recalls Paterson, who was also one of four men to cross Greenland. "In those days it was still a bit of an adventure," he says.

References
  1. Paterson, A.B. & Reeh, N. Thinning of the ice sheet in northwest Greenland over the past forty years. Nature, 414, 60 - 62, (2001).

JOHN WHITFIELD | Nature News Service
Further information:
http://www.nature.com/nsu/011101/011101-13.html
http://www.nature.com/nsu/

More articles from Earth Sciences:

nachricht One-third of recent global methane increase comes from tropical Africa
11.12.2019 | European Geosciences Union

nachricht The Arctic atmosphere - a gathering place for dust?
09.12.2019 | Leibniz-Institut für Troposphärenforschung e. V.

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electronic map reveals 'rules of the road' in superconductor

Band structure map exposes iron selenide's enigmatic electronic signature

Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

The Arctic atmosphere - a gathering place for dust?

09.12.2019 | Earth Sciences

New ultra-miniaturized scope less invasive, produces higher quality images

09.12.2019 | Information Technology

Discovery of genes involved in the biosynthesis of antidepressant

09.12.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>