Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Melting of the Greenland ice sheet mapped

18.09.2009
Will all of the ice on Greenland melt and flow out into the sea, bringing about a colossal rise in ocean levels on Earth, as the global temperature rises?

The key concern is how stable the ice cap actually is and new Danish research from the Niels Bohr Institute at the University of Copenhagen can now show the evolution of the ice sheet 11,700 years back in time – all the way back to the start of our current warm period. The results are published in the esteemed journal Nature.


This is a map of the ice core drilling locations discussed in the article. Credit: Center for Ice and Climate, Niels Bohr Institute, University of Copenhagen

Numerous drillings have been made through both Greenland's ice sheet and small ice caps near the coast. By analysing every single annual layer in the kilometres long ice cores researchers can get detailed information about the climate of the past. But now the Danish researcher Bo Vinther and colleagues from the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen, in collaboration with researchers from Canada, France and Russia, have found an entirely new way of interpreting the information from the ice core drillings.

"Ice cores from different drillings show different climate histories. This could be because they were drilled at very different places on and near Greenland, but it could also be due to changes in the elevation of the ice sheet, because the elevation itself causes different temperatures" explains Bo Vinther about the theory.

Today the ice sheet is more than three kilometres thick at its highest point and thinning out towards the coast. Four of the drillings analysed are from the central ice sheet, while two of the drillings are from small ice caps outside of the ice sheet itself, at Renland on the east coast and Agassiz which lies just off of the northwest coast of Greenland in Canada.

Small ice caps show the standard

The small ice caps are stable and have not changed in elevation, and even though they lie very far apart from each other on either side of the central ice sheet, they show the same climate history. This means that one can use the small ice caps climate history as a standard reference for the others.

Bo Vinther explains, that the four drillings through the ice sheet would have had the same climate history if there had not been changes in elevation throughout the course of time. It is known that for every 100 meter increase in elevation, there is a 0.6 per mille decrease in the level of the oxygen isotope Oxygen-18, which indicates the temperature in the air. So if there is a difference of 1.2 per mille, the elevation has changed by 200 meters.

By comparing the Oxygen-18 content in all of the annual layers from the four drillings through the ice sheet with the Oxygen-18 content of the same annual layers in the small ice caps, Bo Vinther has calculated the elevation course through 11,700 years.

Temperature sensitive ice sheet

Just after the ice age the elevation of the ice sheet rose slightly. This is because when the climate transitions from ice age to warm age, there is a rapid increase in precipitation. But at the same time, the areas lying near the coast begin to decrease in size, because the ice is melting at the edge. When the ice melts at the edge, it slowly causes the entire ice sheet to 'collapse' and become lower.

The calculations show that in the course of about 3,000 years the elevation changed and became up to 600 meters lower in the coastal areas. But in the middle it was a slow process, where the elevation decreased around 150 meters in the course of around 6,000 years. It then stabilised.

The elevations that were found with the help of the Oxygen-18 measurements from the ice cores are checked with other methods, for example, by measuring the air content, which is also dependent upon the elevation.

The new results show the evolution of elevation of the ice sheet throughout 11,700 years and they show that the ice sheet is very sensitive to the temperature. The results can be used to make new calculations for models predicting future consequences of climate changes.

Contact: Bo Møllesøe Vinther, ph.d. Center for Ice and Climate, Niels Bohr Institute, University of Copenhagen, +45 3532-0518, mob: +45 2064-4144 bo@gfy.ku.dk

Jørgen Peder Steffensen, ph.d. Center for Ice and Climate, Niels Bohr Institute, University of Copenhagen, +45 3532-0557, jps@gfy.ku.dk

Gertie Skaarup | EurekAlert!
Further information:
http://www.ku.dk

More articles from Earth Sciences:

nachricht NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center

nachricht The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus 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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>