Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Radar altimetry confirms global warming is affecting polar glaciers

20.03.2006


Scientists have confirmed that climate warming is changing how much water remains locked in the Antarctic and Greenland ice sheets, according to an article published in the Journal of Glaciology.



Using radar altimeter data from ESA’s ERS-1 and ERS-2, Jay Zwally, a scientist at NASA’s Goddard Space Flight Center, and his colleagues mapped the height of the ice sheets and found there was a net loss of ice from the combined sheets between 1992 and 2002 and a corresponding rise in sea level.

Polar ice plays a crucial role in regulating global climate because it reflects about 80 percent of the incoming sunlight. If the ice caps over the polar ocean melt, the ocean water would absorb a large part of the radiation energy, which would lead to further melting of the ice and further warming of the climate.


According to the NASA study, published in the March edition, 20 billion net tonnes of water are added to oceans each year as a result of Greenland’s ice sheet gaining some 11 billion tonnes of water annually, while Antarctica loses about 31 billion tonnes per year.

The study found that Antarctica lost much more ice to the sea than it gained from snowfall, resulting in an increase in sea level, while the Greenland ice sheet gained more ice from snowfall at high altitudes than it lost from melting ice along its coast.

A recent study by Eric Rignot of NASA’s Jet Propulsion Laboratory and University of Kansas scientist Pannir Kanagaratnam, published in Science in February, showed Greenland glaciers are melting into the sea twice as fast as previously believed.

Using satellite data collected between 1996 and 2005 by ESA’s remote sensing satellites ERS-1 and ERS-2, ESA’s Envisat and Canada’s Radarsat-1, they found Greenland’s southern glaciers are now dumping twice as much ice yearly into the Atlantic as they did in 1996, accounting for nearly 17 percent of the estimated 2.54 millimetre annual rise in global sea levels.

The fact that the Greenland glaciers are melting, as determined in Rignot’s study, coupled with the new findings that Greenland’s glaciers are gaining more snow at the top suggests global warming is affecting the ice sheets. When the environment becomes warmer, it builds up water in the atmosphere which can then increase snow fall over Greenland. At the same time, however, the oceans are warming causing the outer sheets of ice to melt.

The question of whether and to what extent global climate change is causing the polar ice caps to shrink is one of the topics being addressed by glaciologists, hydrologists, oceanographers and geodesists from around the world at the ‘15 Years of Progress in Radar Altimetry’ symposium in Venice, Italy, from 13-18 March 2006.

For the last 15 years, radar altimetry – an instrument originally designed to measure the sea surface height – has been successful in measuring large-scale homogenous ice surfaces of Greenland and Antarctica and providing initial global monitoring results for sea ice thickness.

However, in an effort to improve the understanding of the relationship between the Earth’s ice cover and global climate, ESA designed a mission, called CryoSat, to provide detailed views of irregular sloping edges of land ice, as well as non-homogenous ocean ice over a three-year period.

Unfortunately, the mission was lost, on 8 October 2005, due to a malfunction of the Russian rocket launcher. But on 24 February 2006, ESA received the green light from its Member States to build and launch a CryoSat recovery mission, CryoSat-2.

CryoSat-2 will be equipped with an enhanced radar altimeter instrument, called the Synthetic Aperture Interferometric Radar Altimeter (SIRAL), that will allow it to send 17 800 separate radar pulses per second down to Earth per second then record how long their echoes take to bounce back. Currently, the second generation radar altimeter on ESA’s Envisat measures height using the same technique, but sends 1800 pulses down to Earth.

It is important to carry on monitoring over Greenland and Antarctica because the long-term observations by satellites provide authoritative evidence of trends and enable estimation of the consequences should such melting continue into the future.

Mariangela D’Acunto | alfa
Further information:
http://www.esa.int/esaEO/SEMTQUNVGJE_planet_0.html

More articles from Ecology, The Environment and Conservation:

nachricht Despite government claims, orangutan populations have not increased. Call for better monitoring
06.11.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Increasing frequency of ocean storms could alter kelp forest ecosystems
30.10.2018 | University of Virginia

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland

15.11.2018 | Earth Sciences

When electric fields make spins swirl

15.11.2018 | Physics and Astronomy

Discovery of a cool super-Earth

15.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>