New research published in Geophysical Research Letters helps “explain the mechanism that is causing the rapid melting of the West Antarctic glaciers now being observed”. [1, 2]
However, according to the study’s lead author, Paul Spence of the University of New South Wales (UNSW), recent studies [3] suggesting the glaciers may have begun an irreversible melting “may prove optimistic because models had failed to account for how strengthening westerly winds in the Southern Ocean would start to impinge coastal easterlies, upsetting a delicate balance of warm and cold waters close to the Antarctic ice sheets”.
The research found that the coastal temperature structure of Antarctica was more sensitive to global warming, particularly changes to winds, than previously identified, leading to warm offshore water flooding into the ice-shelf regions and increasing the temperatures by 4 degrees Celsius under the ice shelf.
This research is additional to a study from May, 2014, which found that westerly winds in the Southern Ocean had quickened 10-15 percent over the past 50 years, and shifted 2 to 5 degrees closer to the South Pole. A co-author of that study, Matthew England of UNSW, was also a co-author of the latest report. The study had found that, in addition to the ozone hole over Antarctica, greenhouse gas emissions were contributing to the changing winds.[4]
The research highlights the rapidly changing nature of factors affecting climate change. Even before considering such developments, it is important to note that findings and projections from the Intergovernmental Panel on Climate Change (IPCC) are extremely conservative. Factors omitted from IPCC projections include the release of carbon from melting permafrost (frozen soil) around the Arctic and the dynamics of ice sheet loss on Greenland and Antarctica. Former Australian of the Year and head of the Climate Council, Professor Tim Flannery, has described IPCC reports as “painfully conservative”. [5]
Former head of NASA’s Goddard Institute for Space Studies, Dr James Hansen, has said that the IPCC treats sea level change basically as a linear process. He argues that it is more realistic that ice sheet disintegration will be non-linear, which is typical of a system that can collapse. [6]
Another concern is that, due to the time lag involved in producing reports, IPCC projections are generally out of date before they are published.
Commenting on the latest research, Tas van Ommen, a principal research scientist at the Australian Antarctic Division, has said: “Even 10 centimetres [4 inches] of sea-level rise tripled the flooding frequency of the world’s coastal regions.” [7]
With the increased likelihood and consequences of extreme events arising from climate change, governments, corporations and others need to consider and plan for a broad range of scenarios that go beyond the factors allowed for by the IPCC .
Author: Paul Mahony (also on Slideshare, Scribd, and Twitter)
References:
[1] Spence, P., Griffies, S.M., England, M.H., Hogg, A.M., Saenko, O.A., Jourdain, N.C., Geophysical Research Letters, “Rapid subsurface warming and circulation changes of Antarctic coastal waters by poleward shifting winds”, doi: 10.1002/2014GL060613, July, 2014, http://iopscience.iop.org/1748-9326/2/2/024002/fulltext/
[2] Hannam, P., “Bad news for sea-level rises as quickening Antarctic winds point to faster ice melt”, Sydney Morning Herald, 8th July, 2014, http://www.smh.com.au/environment/climate-change/bad-news-for-sealevel-rises-as-quickening-antarctic-winds-point-to-faster-ice-melt-20140707-zsz3o.html
[3] Rignot, E., Mouginot, J., Morlighem, M., Seroussi, H. and Scheuchl, B., “Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011“, Geophysical Research Letters, Published online: 27 May, 2014, DOI: 10.1002/2014GL060140, Volume 41, Issue 10, pages 3502–3509, 28 May 2014, cited in Phillips, A., NASA Science “Science News”, “West Antarctic Glaciers in Irreversible Decline”, 12 May, 2014, http://science.nasa.gov/science-news/science-at-nasa/2014/12may_noturningback/
[4] Abram, N.J., Mulvaney, R., Vimeux, F., Phipps, S.J., Turner, J., England, M.H., “Evolution of the Southern Annular Mode during the past millennium”, Nature Climate Change, Volume: 4, Pages: 564–569, DOI: doi:10.1038/nclimate2235, published online 11th May, 2014, http://www.nature.com/nclimate/journal/v4/n7/full/nclimate2235.html
[5] Spratt, D, “Global Warming – No more business as usual: This is an emergency!”, Environmental Activists’ Conference 2008: Climate Emergency – No More Business as Usual, 10 October, 2008, reproduced in Links International Journal of Socialist Renewal, http://links.org.au/node/683
[6] Hansen, J., “Storms of my granchildren”, Bloomsbury, 2009, pp. 255-256.
[7] Hannam, P. op. cit.
Image: NASA Earth Observatory, Antarctic Warming Trends from 1957 to 2006, 23 Jan 2009, http://earthobservatory.nasa.gov/IOTD/view.php?id=36736
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