False Alarm: Sea Levels Likely To Rise Much Faster Than Was Predicted
Global warming is causing the Greenland ice cap to disintegrate far faster than anyone predicted. A study of the region’s massive ice sheet warns that sea levels may – as a consequence – rise more dramatically than expected.
Scientists have found that many of the huge glaciers of Greenland are moving at an accelerating rate – dumping twice as much ice into the sea than five years ago – indicating that the ice sheet is undergoing a potentially catastrophic breakup.
The implications of the research are dramatic given Greenland holds enough ice to raise global sea levels by up to 21ft, a disaster scenario that would result in the flooding of some of the world’s major population centres, including all of Britain’s city ports.
Satellite measurements of the entire land mass of Greenland show that the speed at which the glaciers are moving to the sea has increased significantly over the past 10 years with some glaciers moving three times faster than in the mid-1990s.
Scientists believe that computer models of how the Greenland ice sheet will react to global warming have seriously underestimated the threat posed by sea levels that could rise far more quickly than envisaged.
The latest study, presented at the American Association for the Advancement of Science, in St Louis, shows that rather than just melting relatively slowly, the ice sheet is showing all the signs of a mechanical break-up as glaciers slip ever faster into the ocean, aided by the “lubricant” of melt water forming at their base. […]
Reality Check: Sea level rise not accelerating
A paper published yesterday in the Journal of Geophysical Research – Oceans, confirms other studies of tide gauge records which show that there has been no statistically significant acceleration in sea level rise over the past 100+ years, in contrast to statements of the IPCC and Al Gore. Sea levels have been rising naturally since the end of the last major ice age 20,000 years ago, and the rate of rise began to decelerate about 8,000 years ago:
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, C08013, 15 PP., 2010: Reconstruction of regional mean sea level anomalies from tide gauges using neural networks – Authors: Manfred Wenzel, Jens Schröter
The 20th century regional and global sea level variations are estimated based on long-term tide gauge records. For this the neural network technique is utilized that connects the coastal sea level with the regional and global mean via a nonlinear empirical relationship. Two major difficulties are overcome this way: the vertical movement of tide gauges over time and the problem of what weighting function to choose for each individual tide gauge record. Neural networks are also used to fill data gaps in the tide gauge records, which is a prerequisite for our analysis technique. A suite of different gap-filling strategies is tested which provides information about stability and variance of the results. The global mean sea level for the period January1900 to December 2006 is estimated to rise at a rate of 1.56 ± 0.25 mm/yr which is reasonably consistent with earlier estimates, but we do not find significant acceleration. The regional mean sea level of the single ocean basins show mixed long-term behavior. While most of the basins show a sea level rise of varying strength there is an indication for a mean sea level fall in the southern Indian Ocean. Also for the the tropical Indian and the South Atlantic no significant trend can be detected. Nevertheless, the South Atlantic as well as the tropical Atlantic are the only basins that show significant acceleration. On shorter timescales, but longer than the annual cycle, the basins sea level are dominated by oscillations with periods of about 50–75 years and of about 25 years. Consequently, we find high (lagged) correlations between the single basins.
Note: The 1.56 mm/yr non-accelerating rate of sea level rise would result in sea levels 6 inches higher than the present in100 years. The oscillations noted in this study correspond to the typical full and half-cycle lengths of the natural Pacific Decadal Oscillation and the natural 60-year climate cycle. The Pacific Decadal Oscillation warm phase has been shown to produce a marked temporary rise in global mean sea levels.