Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Glacial thinning has sharply accelerated at major South American icefields

06.09.2012
For the past four decades scientists have monitored the ebbs and flows of the icefields in the southernmost stretch of South America’s vast Andes Mountains, detecting an overall loss of ice as the climate warms.

A new study, however, finds that the rate of glacier thinning has increased by about half over the last dozen years in the Southern Patagonian Icefield, compared to the 30 years prior to 2000.


The thinning of the Grey Glacier in Patagonia is visible by comparing the current glacier with the bottom of the vegetation line on the surrounding mountains — where the glacier reached until recently. (Credit: Rivera)

“Patagonia is kind of a poster child for rapidly changing glacier systems,” said Michael Willis, lead author of the study and a research associate at Cornell University in Ithaca, New York. “We are characterizing a region that is supplying water to sea level at a big rate, compared to its size.” The Southern Patagonian Icefield together with its smaller northern neighbor, the Northern Patagonian Icefield, are the largest icefields in the southern hemisphere — excluding Antarctica. The new study shows that the icefields are losing ice faster since the turn of the century and contributing more to sea level rise than ever before.

Earlier studies determined that between the 1970’s and 2000 both icefields, which feed into surrounding oceans as they melt, together raised global sea levels by an average of .042 millimeters each year. Since 2000, Willis and his colleagues found that number increased to 0.067 mm of sea level rise on average per year – about two percent of total annual sea level rise since 1998.

The Southern Icefield, which Willis and his colleagues focused on, loses around 20 billion tons (gigatonnes) of ice each year, the scientists calculated, which is roughly 9,000 times the volume of water stored by Hoover Dam annually. Cumulatively, the Southern Patagonian Icefield has lost enough water over the last 12 years to cover the entire United States with 2.7 centimeters (about 1 inch) of water. Include melting of both icefields, and that amount increases to 3.3 centimeters (1.2 inches), the scientists report.

The collaborative study between scientists from Cornell University and the Center for Scientific Studies (CECs) in Valdivia, Chile, is set to be published 5 September in Geophysical Research Letters, a journal of the American Geophysical Union.

To map the changing Southern Patagonian Icefield, Willis and his colleagues collected information from two different satellite missions. Using 156 satellite images taken over the 12-year period by NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument and data from the Shuttle Radar Topography Mission, the scientists mapped how the Southern Patagonian Icefield changed in height and overall size between February 2000 and March 2012.

The team compared its findings with a different set of observations from twin satellites known as the Gravity Recovery and Climate Experiment (GRACE).

“Using ASTER, we think that we have a good idea of where things are changing. But with GRACE we get a good idea of when things are changing. So we have this powerful hybrid,” Willis said. From their new map, the scientists identified individual glaciers and how much each has thinned – i.e. shrunk in height –since 2000. On average, the Southern Patagonian Icefield glaciers have thinned by about 1.8 meters (5.9 feet) per year.

“We find some glaciers are stagnant and even that some have advanced slightly but on the whole, retreat and thinning is prevalent,” Willis said. “Interestingly, we see thinning occurring up to the highest elevations, where presumably it is coldest.”

Warming air temperatures contribute to the thinning at the highest and coldest regions of the ice field, Willis said. Moreover warmer temperatures mean greater chances that rain, as opposed to snow, will fall on and around the glaciers. This double threat of warming and more rain may, in turn, change the amount of water beneath the glaciers. More water means less friction, so the glaciers start to move faster as they thin, moving even more ice in to the oceans. Rising lakes at the front of the glaciers may also play a part as they eat away at the icy edges faster, causing the glaciers to retreat even further.

“Precipitation is a huge component and likely causes large changes in mass input, and therefore net balance,” said Alex Gardner, an assistant professor at Clark University in Worcester, Massachusetts, who was not involved with the study but studies glaciers and ice sheets. “[This new research] shows very high rates of mass loss and it would be great to see a follow up study on how lakes modify these rates of loss.”

Even though scientists have yet to understand exactly how warming temperatures will continue to influence these South American icefields, this new study provides valuable information for future predictions, Gardner said.

“A study like this really provides a strong data set to validate and calibrate glacial models that we could then use to simulate future changes in glaciers,” he said. “Modeling is really the only tool we have to provide future predictions.”

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this paper in press. http://www.agu.org/pubs/crossref/2012/2012GL053136.shtml

Or, you may order a copy of the final paper by emailing your request to Kate Ramsayer at kramsayer@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release are under embargo.

Title:

“Ice Loss from the Southern Patagonian Icefield, South America, between 2000 and 2012”

Authors:
Michael J Willis, Andrew K Melkonian, and Matthew E Pritchard Earth and Atmospheric Sciences, Cornell University, Ithaca, New York, USA;Andres Rivera Centro de Estudios Científicos, Valdivia, Chile, and Departamento de Geografía, Universidad de Chile, Santiago, Chile.
Contact information for the author:
Michael J. Willis, Email: mjw272@cornell.edu

Kate Ramsayer | American Geophysical Union
Further information:
http://www.agu.org

Further reports about: ASTER Geophysical Glacial Icefield Patagonian global sea level ice sheet sea level sea level rise

More articles from Earth Sciences:

nachricht Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg

nachricht First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>