Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Antarctic ice sheet losing mass

03.03.2006


A floating iceberg off the Antarctic Peninsula. Photo courtesy CU-Boulder National Snow and Ice Data Center.


University of Colorado at Boulder researchers have used data from a pair of NASA satellites orbiting Earth in tandem to determine that the Antarctic ice sheet, which harbors 90 percent of Earth’s ice, has lost significant mass in recent years.

The team used measurements taken with the Gravity Recovery and Climate Experiment, or GRACE, to conclude the Antarctic ice sheet is losing up to 36 cubic miles of ice, or 152 cubic kilometers, annually. By comparison, the city of Los Angeles uses about 1 cubic mile of fresh water annually.

"This is the first study to indicate the total mass balance of the Antarctic ice sheet is in significant decline," said Isabella Velicogna of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences, chief author of the new study that appears in the March 2 online issue of Science Express. The study was co-authored by CU-Boulder physics Professor John Wahr of CIRES, a joint campus institute of CU-Boulder and the National Oceanic and Atmospheric Administration.



The estimated ice mass in Antarctica is equivalent to 0.4 millimeters of global sea rise annually, with a margin of error of 0.2 millimeters, according to the study. There are about 25 millimeters in an inch.

The most recent Intergovernmental Panel on Climate Change assessment, completed in 2001, predicted the Antarctic ice sheet would gain mass in the 21st century due to increased precipitation in a warming climate. But the new study signals a reduction in the continent’s total ice mass, with the bulk of loss occurring in the West Antarctic ice sheet, said Velicogna.

Researchers used GRACE data to calculate the total ice mass in Antarctica between April 2002 and August 2005 for the study, said Velicogna, who also is affiliated with the NASA’s Jet Propulsion Laboratory in Pasadena.

"The overall balance of the Antarctic ice is dependent on regional changes in the interior and those in the coastal areas," said Velicogna. "The changes we are seeing are probably a good indicator of the changing climatic conditions there."

Launched in 2002 by NASA and Germany, the two GRACE satellites whip around Earth 16 times a day at an altitude of 310 miles, sensing subtle variations in Earth’s mass and gravitational pull. Separated by 137 miles at all times, the satellites measure changes in Earth’s gravity field caused by regional changes in the planet’s mass, including such things as ice sheets, oceans and water stored in the soil and in underground aquifers.

A change in gravity due to a pass over a portion of the Antarctic ice sheet, for example, imperceptibly tugs the lead satellite away from the trailing satellite, said Velicogna. A sensitive ranging system allows researchers to measure the distance of the two satellites down to as small as 1 micron -- about 1/50 the width of a human hair -- and to then calculate the ice mass in particular regions of the continent.

"The strength of GRACE is that we were able to assess the entire Antarctic region in one fell swoop to determine whether it was gaining or losing mass," said Wahr. While the CU researchers were able to differentiate between the East Antarctic ice sheet and West Antarctic ice sheet with GRACE, smaller, subtler changes occurring in coastal areas and even on individual glaciers are better measured with instruments like radar and altimeters, he said.

A study spearheaded by CIRES researchers at CU-Boulder and published in September 2004 concluded that glaciers on the Antarctic Peninsula - which juts north from the West Antarctic ice sheet toward South America -- sped up dramatically following the collapse of Larsen B ice shelf in 2002. Ice shelves on the peninsula -- which has warmed by an average of 4.5 degrees Fahrenheit in the past 60 years -- have decreased by more than 5,200 square miles in the past three decades.

As Earth’s fifth largest continent, Antarctica is twice as large as Australia and contains 70 percent of Earth’s fresh water resources. The ice sheet, which covers about 98 percent of the continent, has an average thickness of about 6,500 feet. Floating ice shelves constitute about 11 percent of the continent.

The melting of the West Antarctic ice sheet alone - which is about eight times smaller in volume than the East Antarctic ice sheet -- would raise global sea levels by more than 20 feet, according to researchers from the British Antarctic Survey.

Isabella Velicogna | EurekAlert!
Further information:
http://www.colorado.edu

More articles from Earth Sciences:

nachricht Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie

nachricht Modeling magma to find copper
13.01.2017 | Université de Genève

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>