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 Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>