Melting icebergs causing sea level rise

April 28, 2010

Scientists have discovered that changes in the amount of ice floating in the polar oceans are causing sea levels to rise.

The research, published this week in , is the first assessment of how quickly floating ice is being lost today.

According to Archimedes' principle, any floating object displaces its own weight of fluid. For example, an ice cube in a glass of water does not cause the glass to overflow as it melts.

But because sea water is warmer and more salty than floating ice, changes in the amount of this ice are having an effect on global sea levels.

The loss of floating ice is equivalent to 1.5 million Titanic-sized icebergs each year. However, the study shows that spread across the global oceans, recent losses of floating ice amount to a of just 49 micrometers per year - about a hair's breadth.

According to lead author Professor Andrew Shepherd, of the University of Leeds, it would be unwise to discount this signal. "Over recent decades there have been dramatic reductions in the quantity of Earth's floating ice, including collapses of Antarctic ice shelves and the retreat of Arctic sea ice," said Prof Shepherd.

"These changes have had major impacts on regional climate and, because oceans are expected to warm considerably over the course of the 21st century, the melting of should be considered in future assessments of sea level rise."

Professor Shepherd and his team used a combination of satellite observations and a to make their assessment. They looked at changes in the area and thickness of sea ice and ice shelves, and found that the overall signal amounts to a 742 cubic kilometres per year reduction in the volume of floating.

Because of differences in the density and temperature of ice and , the net effect is to increase sea level by 2.6% of this volume, equivalent to 49 micrometers per year spread across the global oceans.

The greatest losses were due to the rapid retreat of and to the collapse and thinning of ice shelves at the Antarctic Peninsula and in the Amundsen Sea.

Explore further: Melting of Floating Ice Will Raise Sea Level

More information: "Recent loss of floating ice and the consequent sea level contribution" by Andrew Shepherd, Duncan Wingham, David Wallis, Katharine Giles, Seymour Laxon, and Aud Venke Sundal is published this week in Geophysical Research Letters, doi:10.1029/2010GL042496

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Doug_Huffman
1.7 / 5 (6) Apr 28, 2010
I wonder if they considered the magnitude of the thermal expansion of water as able to swamp the 49 micrometers due to addition of low salinity water, ... or did I miss something? Glow-bull warning for the gullah-bull!
Billybaroo
2.3 / 5 (3) Apr 28, 2010
Well lets see, 49 micrometers per year equals 0.001929 inches per year. So in 100 years this will add 0.2 inches of rise to ocean levels. Now I'm really scared!
TegiriNenashi
1.8 / 5 (5) Apr 28, 2010
Lies and demagogy. Go to any reputable website and check out for yourself if the ice pack extent changed since the beginning of reliable satellite measurements. Hint: it didn't. Case closed, nothing to see here.
dirk_bruere
5 / 5 (3) Apr 29, 2010
"1.5 million Titanic-sized icebergs"
Well, that makes it perfectly clear. Thanks for not using misleading terms like "tonnes".
Sepp
2.3 / 5 (3) May 01, 2010
Seems like those scientists are desperately looking for sea level rise ... and if it's only micrometers per year.

Doesn't that show how ridiculous the whole global warming argumentation has become?

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