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 Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

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: 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...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

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

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>