Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Greenland ice sheet flow driven by short-term weather extremes, not gradual warming

09.12.2010
Sudden changes in the volume of meltwater contribute more to the acceleration – and eventual loss – of the Greenland ice sheet than the gradual increase of temperature, according to a University of British Columbia study.

The ice sheet consists of layers of compressed snow and covers roughly 80 per cent of the surface of Greenland. Since the 1990s, it has been documented to be losing approximately 100 billion tonnes of ice per year – a process that most scientists agree is accelerating, but has been poorly understood. Some of the loss has been attributed to accelerated glacier flow towards ocean outlets.

Now a new study, to be published tomorrow in the journal Nature, shows that a steady meltwater supply from gradual warming may in fact slow down glacier flow, while sudden water input could cause glaciers to speed up and spread, resulting in increased melt.

“The conventional view has been that meltwater permeates the ice from the surface and pools under the base of the ice sheet,” says Christian Schoof, an assistant professor at UBC’s Department of Earth and Ocean Sciences and the study’s author. “This water then serves as a lubricant between the glacier and the earth underneath it, allowing the glacier to shift to lower, warmer altitudes where more melt would occur.”

Noting observations that during heavy rainfall, higher water pressure is required to force drainage along the base of the ice, Schoof created computer models that account for the complex fluid dynamics occurring at the interface of glacier and bedrock. He found that a steady supply of meltwater is well accommodated and drained through water channels that form under the glacier.

“Sudden water input caused by short term extremes – such as massive rain storms or the draining of a surface lake – however, cannot easily be accommodated by existing channels. This allows it to pool and lubricate the bottom of the glaciers and accelerate ice loss,” says Schoof, who holds a Canada Research Chair in Global Process Modeling.

“This certainly doesn’t mitigate the issue of global warming, but it does mean that we need to expand our understanding of what’s behind the massive ice loss we’re worried about,” says Schoof.

A steady increase of temperature and short-term extreme weather conditions have both been attributed to global climate change. According to the European Environment Agency, ice loss from the Greenland ice sheet has contributed to global sea-level rise at 0.14 to 0.28 millimetres per year between 1993 and 2003.

“This study provides an elegant solution to one of the two key ice sheet instability problems identified by the Intergovernmental Panel on Climate Change in their 2007 assessment report,” says Prof. Andrew Shepherd, an expert on using satellites to study physical processes of Earth’s climate, based at the University of Leeds, the U.K.

“It turns out that, contrary to popular belief, Greenland ice sheet flow might not be accelerated by increased melting after all,” says Shepherd, who was not involved in the research or peer review of the paper.

The research was supported by the Canada Research Chairs Program, the Natural Sciences and Engineering Research Council of Canada, and the Canadian Foundation for Climate and Atmospheric Sciences through the Polar Climate Stability Network.

Brian Lin | EurekAlert!
Further information:
http://www.ubc.ca

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Staying in Shape

16.08.2018 | Life Sciences

Diving robots find Antarctic seas exhale surprising amounts of carbon dioxide in winter

16.08.2018 | Earth Sciences

Protein droplets keep neurons at the ready and immune system in balance

16.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>