May 15, 2012
Media reports claim Antarctica is facing potential meltdown from global warming. “Antarctic ice shelf at tipping point,” warns a headline from TG Daily. “Deep basin under West Antarctic Ice Sheet suggests greater risk of collapse,” cautions Disaster News Network. And msnbc.com quips, “Vast Antarctic ice sheet ‘in play’ with global warming.”
These headlines spin off new research that reveals a previously unknown basin under the West Antarctic Ice Sheet (WAIS) near the Weddell Sea. Using high-tech ice-penetrating radar, a team of scientists from the U.S. and U.K. discovered the sub-glacial basin they say is nearly the size of New Jersey and makes the ice sheet above it vulnerable to collapse. Their study results are published in the current edition of Nature Geoscience.
“If we were to invent a set of conditions conducive to retreat of the West Antarctic Ice Sheet, this would be it,” said Don Blankenship , senior research scientist at The University of Texas at Austin’s Institute for Geophysics. He co-authored the paper with experts from the British Antarctic Survey and the Universities of Edinburgh, Aberdeen, Exeter and York.
A University of Texas press release announcing the results linked this research to a paper published at the same time in the journalNature. Using computer models, it forecasts that warmer ocean water might reach far beneath the WAIS and affect its stability if global temperatures rise in the second half of the 21st century as the U.N. predicts. Scientists say the newly-discovered deep basin makes WAIS particularly vulnerable to potential warm water currents.
Blankenship admits “that losing the ice over this new basin would only raise sea level by a small percentage of the several meters that would result if the entire [WAIS] destabilized.” His co-author Martin Siegert of the University of Edinburgh went on to say, “The area is on the brink of change, but it is impossible to predict what the impact of this change might be without further work enabling better understanding of how the [WAIS] behaves.” Interestingly, they reported the topography of the basin floor indicates “it has been covered with marine sediment and was previously deglaciated” and that area glacial formations “testify to the position of a former ice margin about 200 km inland from the present margin.”
Could such drastic changes be well within the range of natural variability? Swedish geologist and physicist Nils-Axel Morner, former president of the International Union for Quaternary Research Commission on Sea Level Changes and Coastal Evolution, calls the fear over sea level rise a false alarm. He published an article in the Spectator detailing his 45-year career including numerous field studies in island and coastal nations that show no significant rise in sea levels — in some cases diminishing levels — much to the chagrin of those countries’ officials petitioning the United Nations for international aid from carbon-hungry developed nations. He explains that his findings are quite different from the mainstream because dire predictions of catastrophic sea level rise are based on computer models, whereas his research is based on real-world observation. He said sea levels were well below present levels in the 18th century and well above them in the 17th century, but explaining the natural variability is difficult because there are so many influential factors at play.
Dr. Timothy Ball, climatologist and retired award-winning professor with the University of Winnipeg, explains some of these variables in his paper “When Sea Level Change is Not Sea Level Change.” He describes the dynamic process of eustasy (sea level rise and fall) and isostasy (continental rise and fall), showing that natural sea level rise has been occurring since the peak of the last Ice Age about 20,000 years ago and has slowed dramatically in the last few hundred years. The interplay of eustasy and isostasy results in a compensating mechanism: as heavy ice melts, the land mass it was resting on rebounds.
The relationship is well-known in climate circles but far from squelching debate has fueled it further. Writing for The Heartland Institute, James M. Taylor reports NASA researchers are using the eustasy/isostasy interaction as an excuse to doctor their data. He says the University of Colorado’s NASA-funded Sea Level Research Group announced last year it would begin “adding 0.3 millimeters per year of fictitious sea level rise to ‘compensate’ for rising land mass.” Taylor predicts, “As a result, alarmists will be able to present sea level charts asserting an accelerating rise in sea level that is not occurring in the real world.”
This article was posted: Tuesday, May 15, 2012 at 2:40 am