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NASA: Earth Is Losing Half A Trillion Tons Of Ice A Year
Topic Started: Feb 23 2012, 04:35 AM (359 Views)
Brewster
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Global Ice Loss from 2003-2010 Could Cover the Entire US in One and Half Feet of Water

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In the first comprehensive satellite study of its kind, a University of Colorado at Boulder-led team used NASA data to calculate how much Earth's melting land ice is adding to global sea level rise.

Using satellite measurements from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE), the researchers measured ice loss in all of Earth's land ice between 2003 and 2010, with particular emphasis on glaciers and ice caps outside of Greenland and Antarctica.

The total global ice mass lost from Greenland, Antarctica and Earth's glaciers and ice caps during the study period was about 4.3 trillion tons (1,000 cubic miles), adding about 0.5 inches (12 millimeters) to global sea level. That's enough ice to cover the United States 1.5 feet (0.5 meters) deep.

'Earth is losing a huge amount of ice to the ocean annually, and these new results will help us answer important questions in terms of both sea rise and how the planet's cold regions are responding to global change," said University of Colorado Boulder physics professor John Wahr, who helped lead the study. "The strength of GRACE is it sees all the mass in the system, even though its resolution is not high enough to allow us to determine separate contributions from each individual glacier."

About a quarter of the average annual ice loss came from glaciers and ice caps outside of Greenland and Antarctica (roughly 148 billion tons, or 39 cubic miles). Ice loss from Greenland and Antarctica and their peripheral ice caps and glaciers averaged 385 billion tons (100 cubic miles) a year. Results of the study will be published online Feb. 8 in the journal Nature.

Traditional estimates of Earth's ice caps and glaciers have been made using ground measurements from relatively few glaciers to infer what all the world's unmonitored glaciers were doing. Only a few hundred of the roughly 200,000 glaciers worldwide have been monitored for longer than a decade.

One unexpected study result from GRACE was that the estimated ice loss from high Asian mountain ranges like the Himalaya, the Pamir and the Tien Shan was only about 4 billion tons of ice annually. Some previous ground-based estimates of ice loss in these high Asian mountains have ranged up to 50 billion tons annually.

"The GRACE results in this region really were a surprise," said Wahr, who is also a fellow at the University of Colorado-headquartered Cooperative Institute for Research in Environmental Sciences. "One possible explanation is that previous estimates were based on measurements taken primarily from some of the lower, more accessible glaciers in Asia and extrapolated to infer the behavior of higher glaciers. But unlike the lower glaciers, most of the high glaciers are located in very cold environments and require greater amounts of atmospheric warming before local temperatures rise enough to cause significant melting. This makes it difficult to use low-elevation, ground-based measurements to estimate results from the entire system."

"This study finds that the world's small glaciers and ice caps in places like Alaska, South America and the Himalayas contribute about 0.02 inches per year to sea level rise," said Tom Wagner, cryosphere program scientist at NASA Headquarters in Washington. "While this is lower than previous estimates, it confirms that ice is being lost from around the globe, with just a few areas in precarious balance. The results sharpen our view of land-ice melting, which poses the biggest, most threatening factor in future sea level rise."

The twin GRACE satellites track changes in Earth's gravity field by noting minute changes in gravitational pull caused by regional variations in Earth's mass, which for periods of months to years is typically because of movements of water on Earth's surface. It does this by measuring changes in the distance between its two identical spacecraft to one-hundredth the width of a human hair.
LINK

Polar ice sheet mass loss is speeding up, on pace for 1 foot sea level rise by 2050. It'll get much worse after that.

We'll soon have a choice - we can boil ourselves near the rising sea, or bake ourselves at drought-ridden inland points like Texas.


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Chris
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"Global Ice Loss from 2003-2010 Could Cover the Entire US in One and Half Feet of Water"

"The total global ice mass lost from Greenland, Antarctica and Earth's glaciers and ice caps during the study period was about 4.3 trillion tons (1,000 cubic miles), adding about 0.5 inches (12 millimeters) to global sea level. That's enough ice to cover the United States 1.5 feet (0.5 meters) deep."

Sounded like the entire planet. Is that 1.5 meters higher than the highest point?


What data for the previous millenia do we have to compare with? Do we have data? Or mainly estimates based on inference from small amounts of data.
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Pat
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Interesting study, but I don't see where it has been peer reviewed nor are any base points shown is proof given in the article to base any value in. How deep was the ice at the points where the measurements were taken? What method was used to derive at the figure? How much of the melted ice is trapped in the atmosphere?

Since the United States accounts for 3% of the planets surface, in reality, the ice loss, or should I say any undetermined amount would be negligible.
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Brewster
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So now you don't believe NASA? They have enough scientists internally for peer review, although I'm sure it will appear in many periodicals shortly.

As the article states, the measurements were taken by the GRACE satellite. The last pararaph gives a rough idea of how it works. You could look online for more details if you want.

They agree in general with other studies, although GRACE is far more sensitive than any previous methods, so there is not a lot of external checking that can be done. Doing a better job of measuring is a bad thing?

And what would the percent of the surface covered by the US have to do with anything? GRACE measures the entire Earth. They simply used the "Cover the US" metaphore to stimulate your imagination. Apparently it didn't work.

Stick with the line that the melting ice has raised sea levels half an inch. and consider what will happen to all the ice on the shores of Greenland and Antarctica if it lifts even that little bit off the underlying rock. Think "accelerating slide".
Edited by Brewster, Feb 23 2012, 06:20 AM.
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The only variable is how much of that ice is on land. Any ice on the ocean should not contribute to sea level rise.
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Pat
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The reason I question the study Brew is based in my suspicion and skepticism concerning government studies. And NASA is a government agency that answers to the power and philosophy of the current administration. Find a problem, present a study and theory, followed by regulations and laws designed to fit the solution advocated by those in power. And given Barry and his penchant for green activism, I'm highly suspicious of the studies involving climate questions.
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Brewster
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Well Obama has shown very little activism that I've seen, but I don't know why that should matter.

NASA launched the GRACE satellites in 2002 under George Bush, and as far as I know has had the same program running ever since.

Telco, this particular study is entirely about ice that was on land.
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I try to maintain skepticism, but if this is 50% true, it is alarming.
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Brewster
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Wait 'til the Pine Island Glacier lifts on that extra half inch of water, as it will in the next 6-10 months...

Then we'll see alarming!

Of course, then the Deniers will claim that the Penguins are in on the plot.
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Chris
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telco, compared to what?
Edited by Chris, Feb 23 2012, 09:15 AM.
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