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 Seismic study reveals huge amount of water dragged into Earth's interior
18.12.2018 | National Science Foundation

nachricht A damming trend
17.12.2018 | Michigan State University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New megalibrary approach proves useful for the rapid discovery of new materials

Northwestern discovery tool is thousands of times faster than conventional screening methods

Different eras of civilization are defined by the discovery of new materials, as new materials drive new capabilities. And yet, identifying the best material...

Im Focus: Data storage using individual molecules

Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.

Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Scientists to give artificial intelligence human hearing

19.12.2018 | Information Technology

Newly discovered adolescent star seen undergoing 'growth spurt'

19.12.2018 | Physics and Astronomy

From a plant sugar to toxic hydrogen sulfide

19.12.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>