Tom
Carl Remick wrote:
> >BTW, does anyone know what effect it would
> >have on world ocean levels if the ice covering arctic land masses melted?
> >
> >Carl
>
> [Funny I should ask. Here's what the U.S. Environmental Protection Agency
> has to say on the subject.]
>
> Sea Level
>
> Warmer temperatures are expected to raise sea level by expanding ocean
> water, melting mountain glaciers, and melting parts of the Greenland Ice
> Sheet. Warmer temperatures also increase precipitation, as described below.
> Snowfall over Greenland and Antarctica is expected to increase by about 5
> percent for every 1°F warming in temperatures. Increased snowfall tends to
> cause sea level to drop if the snow does not melt during the following
> summer, because the only other place for the water to be is the ocean. (The
> amount of water in the atmosphere is less than the water it takes to raise
> the oceans one millimeter). Considering all of these factors, the IPCC
> estimates that sea level will rise 20 to 86 cm by the year 2100. A recent
> EPA study estimated that global sea level has a 50 percent chance of rising
> 45 cm (1-1/2 ft) by the year 2100, but a 1-in-100 chance of a rise of about
> 110 cm (over 3-1/2 ft).
>
> Over the longer run, more substantial changes in sea level are possible.
> Some scientists believe that the West Antarctic Ice Sheet could slide into
> the oceans after a sustained warming, or if other factors raised sea level.
> The vulnerability of this ice sheet is poorly understood. It contains enough
> ice to raise sea level 6 meters (20 feet), and coastal scientists generally
> agree that sea level was 20 feet higher than today during the last
> interglacial period, which was only slightly warmer than today. While some
> scientists have suggested that there is fossil evidence on the polar ocean
> floor that this ice sheet collapsed during the last interglacial period,
> there is no scientific consensus on this question.
>
> An EPA study solicited the opinions of 8 US glaciologists on the
> vulnerability of this ice sheet. All but one concluded that Antarctica is
> most likely to have a negligible contribution to sea level over the next
> century. Nevertheless, they all agreed that there is some risk that a
> catastrophic collapse of the ice sheet could occur over a couple of
> centuries if polar water temperatures warm by a few degrees. Most of the
> scientists estimated that such a risk had a probability of between 1 and 5
> percent. Because of this risk, as well as the possibility of a larger than
> expected melting of the Greenland Ice Sheet, the EPA study estimated that
> there is a 1 percent chance that global sea level could rise by more than 4
> meters (almost 14 feet) in the next two centuries.
>
> Sea level rise along the US coast is likely to be somewhat greater than the
> global average. The EPA study includes a set of projections that coastal
> residents can use to calculate how much sea level will rise in specific
> communities. Along the coast of New York, which typifies the US Coast, sea
> level is likely to rise 26 cm (10 inches) by 2050 and 55 cm (almost 2 feet)
> by 2100. There is also a 1 percent chance of a 55 cm rise by 2050, a 120 cm
> rise (4 ft) by 2100, and a 450 cm rise (15 feet) by the year 2200.
>
> [end]
>
> Carl
>
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