The latest fun: Polar ice melt raising sea levels rapidly, claims new study



The media report below is all alarm. But below the media report I reproduce the more cautious journal abstract upon which the report is based. And then we will look at something really amusing:

The pace at which the Greenland and Antarctic ice sheets are melting is "accelerating rapidly" and raising the global sea level, according to findings of a study financed by NASA. The findings suggest that the ice sheets - more so than ice loss from earth's mountain glaciers and ice caps - have become "the dominant contributor to global sea level rise, much sooner than model forecasts have predicted".

This study, published on Tuesday, the longest to date examining changes to polar ice sheet mass, combined two decades of monthly satellite measurements with regional atmospheric climate model data to study changes in mass. "That ice sheets will dominate future sea level rise is not surprising - they hold a lot more ice mass than mountain glaciers," said lead author Eric Rignot, jointly of NASA's Jet Propulsion Laboratory and the University of California, Irvine.

"What is surprising is this increased contribution by the ice sheets is already happening," he said. Under the current trends, he said, sea level is likely to be "significantly higher" than levels projected by the United Nations climate change panel in 2007.

Isabella Velicogna, co-author of the study, said that the ice sheets lose mass by melting or by breaking apart in blocks of ice, which float into the ocean. "It's related to the warming of the planet but that was not the point of the paper. We just observed the changes,"Professor Velicogna said. "It's losing mass - much more than was expected many years ago."

The study showed that in 2006, a year in which comparable results for loss from mountain glaciers and ice caps are available, the Greenland and Antarctic ice sheets lost enough mass to raise global sea levels by an average of 1.3mm a year.

The year-on-year acceleration rate of loss on mountain glaciers and ice caps was three times smaller than that of the ice sheets, the study said. "The authors conclude that, if current ice sheet melting rates continue for the next four decades, their cumulative loss could raise sea level by 15 centimetres by 2050," the report said.

"When this is added to the predicted sea level contribution of eight centimetres from glacial ice caps and nine centimetres from ocean thermal expansion, total sea level rise could reach 12.6 inches [32 centimetres]," it said.

The findings were published the March edition of Geophysical Research Letters.

SOURCE

Abstract

Ice sheet mass balance estimates have improved substantially in recent years using a variety of techniques, over different time periods, and at various levels of spatial detail. Considerable disparity remains between these estimates due to the inherent uncertainties of each method, the lack of detailed comparison between independent estimates, and the effect of temporal modulations in ice sheet surface mass balance. Here, we present a consistent record of mass balance for the Greenland and Antarctic ice sheets over the past two decades, validated by the comparison of two independent techniques over the last 8 years: one differencing perimeter loss from net accumulation, and one using a dense time series of time-variable gravity. We find excellent agreement between the two techniques for absolute mass loss and acceleration of mass loss. In 2006, the Greenland and Antarctic ice sheets experienced a combined mass loss of 475 ± 158 Gt/yr, equivalent to 1.3 ± 0.4 mm/yr sea level rise. Notably, the acceleration in ice sheet loss over the last 18 years was 21.9 ± 1 Gt/yr2 for Greenland and 14.5 ± 2 Gt/yr2 for Antarctica, for a combined total of 36.3 ± 2 Gt/yr2. This acceleration is 3 times larger than for mountain glaciers and ice caps (12 ± 6 Gt/yr2). If this trend continues, ice sheets will be the dominant contributor to sea level rise in the 21st century.

SOURCE

Notice something in the abstract? More than the first quarter of it is devoted to saying how unreliable are the gravity-based measurements they use. They then of course go on to claim that they have got it right. That they have got it WRONG is obvious however. Why? Because their fundamental claim that sea levels are rising at an accelerating rate is false! The satellite data shows in fact that sea level rise rates have slowed in the last five years.


Data from here

Quite mad. They were so fixated on fiddling with their measurement methods that they forgot, in effect, to look out the window


More here

3 comments:

  1. They don't actualy say that sea levels have acclerated. They say ice sheet melting has accelerated. This seems consistent with the reports that the arctic region is warmer now. So perhaps they have looked outside and it may be you that needs to take a less biased look around;maybe?

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  2. John, Here's the link to a 1922 newspaper article about the melting ice. Snopes suggests we may be confusing short term variations with long term trends. No kidding! Keep up the good work.
    Bob Wray
    http://www.snopes.com80/politics/science/globalwarming1922.asp

    ReplyDelete
  3. Sorry. Left out a colon. Try this link:
    http://www.snopes.com:80/politics/science/globalwarming1922.asp
    Bob Wray

    ReplyDelete

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