Ice Sheet Complexity Leaves Sea Level Rise Uncertain

Ice shed from the giant sheets covering Antarctica and Greenland is responsible for just 12% of the current rate of global sea level rise, according to a new review.

The authors emphasise that it is now clear that the ice caps are losing ice faster than it is being replenished by snowfall. But exactly why this is happening remains unknown, making it difficult to predict the extent of future sea level rises.

The remaining 88% of the current rise is due to the expansion of water as it warms, and melting from mountain glaciers and ice caps outside Greenland and Antarctica. Yet the shrinking of Greenland and Antarctica remains crucial because together they hold enough water to make sea levels rise by 70 metres, submerging vast swathes of land and displacing millions.

Over the past 10 years, satellite measurements have vastly improved the quality of data detailing changes in the ice sheets, say Duncan Wingham from University College London and Andrew Shepherd from the University of Edinburgh, both in the UK.

Having reviewed the latest data, the pair conclude that losses from the ice sheets of Greenland and Antarctica contribute 0.35 millimetres per year to the total rate of sea level rise, estimated at 3 mm per year.

This contribution is close to the Intergovernmental Panel on Climate Change's latest estimate of 0.41 mm from the Greenland and Antarctic ice sheets. According to the IPCC, measurements since 1993 show that the thermal expansion of water is responsible for 1.6 mm of the annual rise and other melting glaciers and ice caps for 0.77 mm.

The satellite data have revealed how the ice sheets are losing mass. "It has become

First, sea level has been increasing at 1 to 3 mms per year every year since the end of the ice age. More precisely, the sea level has been rising at 1 to 3 mms per year since the bulk of the ice age glaciers disappeared about 6,000 years ago. Before that, sea level was rising as fast as 5 cms (2 inches) per year at the the heighth of ice age melting.

It is natural in an interglacial like we are in for the sea level to rise very slowly even after the bulk of the ice age glaciers have melted.

Other satellite measures show that Greenland and Antarctica are increasing in ice mass.

So as usual, the study is data selection and not telling the complete story, so that the general public is mislead.

The authors, however, will now be invited to all the great global warming parties and they will have their grant applications approved.

So as usual, the study is data selection and not telling the complete story, so that the general public is mislead

This is SO true, and all you have to do to witness the deception is read the recent SPM AR4 (Summary for Policy Makers, 4th Assessment Report) released by the IPCC in February. In it, they have a section claiming to present sea level rise evidence as further proof of global warming. Here is a link to the report. Fourth Assessment Report SPM

In this report, there is a graph (Fig. SPM-3, page 6) of sea level rise over the 20th century up to the present, with the last 10 years highlighted in red. A little bit further down the report is a table (Table SPM-1, page 7). This table presents the observed sea level rise over the period from 1961-2003, for a reported average of 1.8 mm/year. They then compare this against the years 1993-2003, which they calculate to be a rate of 3.1 mm/year.

The objective is to present an alarming increase rate which changed from 1.8 to 3.1 mm/year, presumably a result of global warming.

But is this fair?? Or is it data cherry picking? One might fairly ask... Why choose 1961 as the first year in a long range???Choosing the year 1961 as the starting point of a longer range seems a bit peculiar. What is so special about 1961? If you look at the graph, you will see why they decided to use that as the reference rate. That is because if they went further back in time, they would get a steeper rate to compare against the more recent rate, and they didn't want that. You see, there was another steep rate rise from 1925 to 1961 which they didn't want to include in their calculations. Wonder why?? I'll tell you why. If they had chosen a starting date of, say, 1925 to the present, they would have had a reference rate closer to 2.2 mm/year. They decided it was more emphatic to use a reference of 1.8 instead of 2.2. This is TYPICAL of the IPCC's unscientific proclivity to cherry-pick data for their conclusions.

A final point I would like to make is the use in this case of data from a short time period. If global warming skeptics tried to use data over a short period of time to disprove the IPCC's theories, they would argue that short periods are not reliable. For instance, skeptics often point out that temperatures have been nearly flat over the last 6 or 7 years, suggesting a leveling off of recent temperature rise. IPCC defenders argue back that you can't use short time periods for argument. Yet the IPCC in their report chooses the last 10 years of observed sea-level rise to use as a comparison against longer-term rise rates. THIS IS SCIENTIFIC AND INTELLECTUAL DISHONESTY IN IT'S MOST DESPICABLE FORM AND SHOULD BE THROWN IN THE FACE OF THE IPCC!! \

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