NASA provides new perspectives on the earth's changing ice sheetsDecember 12, 2006It's widely documented that climate change is causing the Greenland and Antarctic ice sheets to shrink. Air temperatures in many parts of the polar regions have increased and waters that surround parts of the ice sheets have warmed up. What most do not know is that until just six years ago, we had no real way of measuring whether the ice sheets were shrinking or growing, or at what rate. Today, advances in remote sensing, the use of highly sensitive instruments aboard satellites and aircraft, have enabled scientists to examine the mass balance of the ice sheets and to determine just where and how quickly the ice is growing or shrinking. Of particular importance is the mass balance of the ice sheet, which is the difference between how much ice it has lost versus gained over a period of time, and is a direct measure of an ice sheet's contribution to sea level rise. With increases in the number of ways researchers can now measure changes in the landscape and rate of change of the ice sheets, have also come some variations in scientific results that some may find confusing. However, a closer look tells a fairly consistent story.
"The media has reported a lot about how ice is changing, particularly in Greenland, but the numbers vary depending on the time period examined and the technique used. As a result, there may be some confusion out there about what's really happening," said Waleed Abdalati, a glacier expert and head of the Cryospheric Sciences Branch at NASA's Goddard Space Flight Center, Greenbelt, Md. "We have all these techniques and some are giving different answers than others. But what's significant is that we have the ability to even debate ice sheet measurement results at all when we could not have a few years ago. Now, we're talking about how much ice sheet shrinkage there is and how rapidly it's taking place." Researchers now use aircraft altimetry, satellite radar and laser altimetry, radar interferometry, gravity measurements from NASA's Gravity Recovery and Climate Experiment (GRACE) mission and precise elevation change measurements from NASA's Ice, Cloud, and Land Elevation (ICESat) satellite. Each tool has its own strengths, and when used together, these technologies produce a comprehensive look into the ice sheets' behavior that have changed the way the world thinks of climate change and its impact on ice sheets and glaciers. Each of these provides important information for unraveling the behavior of the ice sheets, and collectively they tell a story. In Greenland, they reveal an ice sheet that is shrinking dramatically at the edges and growing at its higher interior elevations, such that there is a net loss of ice that is far greater than it was in the last decade. These losses are a result of increased melting, and faster flow at the edges, as the floating ice that surrounds parts of Greenland and buttresses some of the outlet glaciers melts. In Antarctica, these observations tell us that the West Antarctic ice sheet is currently shrinking substantially, and has been for the last decade. They also tell a story of a second much larger ice sheet in East Antarctica that has been growing slowly. The net result in Antarctica is that the ice sheet as a whole has been shrinking, contributing to rising sea levels, and probably much more so in recent years. "We did not appreciate in the past how the changes in ice sheets respond so quickly to changes in climate. The story these measurement techniques are all telling is that the ice sheets are shrinking more than they were 10 years ago," said Abdalati. "The borders of the ice sheets are melting in waters that are warming." "Of the techniques for measuring ice sheet change, the laser altimetry approach of the ICESat mission is the most effective because it provides a detailed look at the overall integrated changes in the ice sheets," offered Abdalati. "And continuous observations like those by ICESat would greatly enhance our ability to understand what's really happening to the Earth's dramatically changing ice cover. The most telling comprehensive picture, however, is created when all the techniques are used together." NASA/Goddard Space Flight Center Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Venus Cancer Vaccine Malignant Melanoma Lupus Trauma Stem Cell Alcoholics Cosmic Radiation Gene Mutations Tumor cell Eye Cancer Psoriasis Solar Energy Hot Flashes Superconductivity Smoking cessation Gene Mutation Coral reef Wine Cardiac Death Clostridium difficile Kidney Disease Nicotine Saturns Rings Epigenetics
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Related Ice Sheets Current Events and Ice Sheets News Articles Close relationship between past warming and sea-level rise In a paper in Nature Geoscience, a team from the National Oceanography Centre, Southampton (NOCS), along with colleagues from Tübingen (Germany) and Bristol presents a novel continuous reconstruction of sea level fluctuations over the last 520 thousand years. Ice Sheets Can Retreat Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists at the University at Buffalo. University of Leicester geologists demonstrate extent of ancient ice age Geologists at the University of Leicester have shown that an ancient Ice Age, once regarded as a brief 'blip', in fact lasted for 30 million years. CU-Boulder study shows 53 million-year-old high Arctic mammals wintered in darkness Ancestors of tapirs and ancient cousins of rhinos living above the Arctic Circle 53 million years ago endured six months of darkness each year in a far milder climate than today that featured lush, swampy forests. Melting Greenland Ice Sheets May Threaten Northeast United States, Canada Melting of the Greenland ice sheet this century may drive more water than previously thought toward the already threatened coastlines of New York, Boston, Halifax, and other cities in the northeastern United States and Canada. Melting threat from West Antarctic Ice Sheet may be less than expected, could hit US hardest While a total or partial collapse of the West Antarctic Ice Sheet as a result of warming would not raise global sea levels as high as some predict, levels on the U.S. seaboards would rise 25 percent more than the global average and threaten cities like New York, Washington, D.C., and San Francisco, according to a new study. Threat from West Antarctica less than previously believed The potential contribution to sea level rise from a collapse of the West Antarctic Ice Sheet (WAIS) have been greatly overestimated, according to a new study published in the journal Science. New Antarctic seabed sonar images reveal clues to sea-level rise Motorway-sized troughs and channels carved into Antarctica's continental shelves by glaciers thousands of years ago could help scientists to predict future sea-level rise. Unlikely life thriving at Antarctica's Blood Falls An unmapped reservoir of briny liquid chemically similar to sea water, but hidden under an inland Antarctic glacier, appears to support microbial life in a cold, dark, oxygen-poor environment -- a most unexpected setting to be teeming with life. Unusual Antarctic microbes live life on a previously unsuspected edge An unmapped reservoir of briny liquid chemically similar to sea water, but buried under an inland Antarctic glacier, appears to support unusual microbial life in a place where cold, darkness and lack of oxygen would previously have led scientists to believe nothing could survive, according to newly published research. More Ice Sheets Current Events and Ice Sheets News Articles |
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