Or satellite radar altimetry, which measures sea level at thousands of points on the ocean surface, and then calculates sea level rise over time.
Posted on 03/03/2006 9:58:52 AM PST by Antroad
Whatever the course the world climate might take I think that mankind is powerless to alter it's course for good or ill.
That said the greenies are being short sighted in missing one possible ramification. Can you imagine the explosion of Arctic sea life should the amount of Arctic multi-year ice decrease?
And that's assuming that all that water is going to end up in the ocean. What about refilling freash water lakes and getting tied up in vegetation that could grow from increased rainfall in near desert areas? There's a lot of places that water could be absorbed that would keep it from going into the oceans.
Good, I expect that my property value will go up accordingly. I'll be a BILLIONAIRE!!!!!!!!!!!!!!!!
Or satellite radar altimetry, which measures sea level at thousands of points on the ocean surface, and then calculates sea level rise over time.
I'm glad you didn't say "unbiased", considering that Patrick Michaels has made a career out of a) denying global warming is taking place, and b) once faced with the reality of global warming taking place [and admitting it], denying that anything significant will happen because of it. What's (c) going to be, I wonder? {I hope that wasn't too impolite; Michaels is nothing if not predictable.}
Prior to this study hitting the news, I previously discussed other measurements of the Greenland and Antarctic ice sheets. The Greenland trends are considered in line with global warming predictions when there is a warmer ocean surface; i.e., mass gain at the higher elevations due to increased precipitation caused by increased water vapor in the atmosphere, and increased melting at lower elevations due to higher temperatures. Other Antarctic measurements using satellite altimetry show that the West Antarctic ice sheet is losing significant mass, the East Antarctic ice sheet is gaining a bit, for an overall loss of mass. This is based on nine years of data, not three, but the trends are consistent. Also note that the West Antarctic ice sheet is considered less stable than the East Antarctic ice sheet.
I don't think that they are directly trying to address global warming here. I found a press release on the study, and I'm providing it below. Note the parts I've highlighted.
NASA Mission Detects Significant Antarctic Ice Mass Loss Scientists were able to conduct the first-ever gravity survey of the entire Antarctic ice sheet using data from the joint NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE). This comprehensive study found the ice sheet's mass has decreased significantly from 2002 to 2005.
Isabella Velicogna and John Wahr, both from the University of Colorado, Boulder, conducted the study. They demonstrated for the first time that Antarctica's ice sheet lost a significant amount of mass since the launch of GRACE in 2002. The estimated mass loss was enough to raise global sea level about 1.2 millimeters (0.05 inches) during the survey period; about 13 percent of the overall observed sea level rise for the same period.
The researchers found Antarctica's ice sheet decreased by 152 (plus or minus 80) cubic kilometers of ice annually between April 2002 and August 2005. That is about how much water the United States consumes in three months (a cubic kilometer is one trillion liters; approximately 264 billion gallons of water). This represents a change of about 0.4 millimeters (.016 inches) per year to global sea level rise. Most of the mass loss came from the West Antarctic ice sheet.
"Antarctica is Earth's largest reservoir of fresh water," Velicogna said. "The GRACE mission is unique in its ability to measure mass changes directly for entire ice sheets and can determine how Earth's mass distribution changes over time. Because ice sheets are a large source of uncertainties in projections of sea level change, this represents a very important step toward more accurate prediction, and has important societal and economic impacts. As more GRACE data become available, it will become feasible to search for longer-term changes in the rate of Antarctic mass loss," she said.
Measuring variations in Antarctica's ice sheet mass is difficult because of its size and complexity. GRACE is able to overcome these issues, surveying the entire ice sheet, and tracking the balance between mass changes in the interior and coastal areas.
Previous estimates have used various techniques, each with limitations and uncertainties and an inherent inability to monitor the entire ice sheet mass as a whole. Even studies that synthesized results from several techniques, such as the assessment by the Intergovernmental Panel on Climate Change, suffered from a lack of data in critical regions.
"Combining GRACE data with data from other instruments such as NASA's Ice Cloud and land Elevation Satellite, radar and altimeters that are more effective for studying individual glaciers is expected to substantially improve our understanding of the processes controlling ice sheet mass variations," Velicogna said.
The Antarctic mass loss findings were enabled by the ability of the identical twin GRACE satellites to track minute changes in Earth's gravity field resulting from regional changes in planet mass distribution. Mass movement of ice, air, water and solid earth reflect weather patterns, climate change and even earthquakes. To track these changes, GRACE measures micron- scale variations in the 220 kilometer (137 mile) separation between the two satellites, which fly in formation.
GRACE is managed for NASA by the Jet Propulsion Laboratory (JPL), Pasadena, Calif. The University of Texas Center for Space Research has overall mission responsibility. GeoForschungsZentrum Potsdam (GFZ), Potsdam, Germany, is responsible for German mission elements. Science data processing, distribution, archiving and product verification are managed jointly by JPL, the University of Texas and GFZ. The results will appear in this week's issue of Science.
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Now, I'm sure that policy-sensitive entities will attempt to spin or anti-spin a result like this to suit their biases. But please note that the scientists don't say a whit about global warming, they know that the study is only applicable to the GRACE mission period, and they need more data before they can make longer-term assessments and predictions. Are the scientists involved really trying to prove anything about an "alarmist" theory? Or is Patrick Michaels spinning the story a certain way so that he can soothe his constituency? You decide.
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