Monday, November 28, 2011

Attenborough warns of ice shelf destruction in Antarctica

UK Naturalist and documentary maker David Attenborough has warned about the implications of melting ice sheets in the polar regions but emphasised the changes under way in Antarctica "is likely to have the most dramatic effects of all".

His comments were made in a November 2011 article in the BBC Radio Times reported by the Independent newspaper. While the title of the Independent newspaper article - Warning over melting ice at North Pole - places emphasis on processes in the Arctic, the important statement by Attenborough is about the collapse of ice shelves fringing Antarctica and the implications for the West Antarctic Ice Sheet.

David Attenborough said "The meltwaters from Greenland's glaciers alone could cause a rise in global sea levels of up to half a metre by the end of this century,"

Attenborough visited both the Arctic and Antarctic in the making of the seven part series about planet Earth's cryosphere - Frozen Planet (BBC Frozen Planet website). The film team witnessed not only the melting of Arctic sea ice, but the calving of icebergs from glaciers in Greenland and Antarctica which contributes to sea level rise.

"It is the change to the permanent ice that fringes the coasts of Antarctica that is likely to have the most dramatic effects of all," Attenborough said.

If global warming leads to the collapse of the ice shelves in Antarctica, "vast quantities of land ice and meltwater will slide into the sea and cause a major rise in sea levels around the globe", he said.

"When that will happen and by how much are difficult questions. But with over half of the human population living near the coast, the answers may be only too devastating." concluded Attenborough.

There are already signs of the West Antarctic Ice Sheet (WAIS) losing ice mass. I reported on November 6, 2011 on Global Warming in Antarctica: Thwaites and Pine Island Glaciers accelerating, West Antarctic Ice Sheet losing mass.

Unfortunately the BBC decided to make the seventh episode of Frozen Planet optional for overseas networks to purchase and broadcast, valuing the income to be earned more than the message of the seventh episode. The seventh episode details the changes happening in polar regions with global warming and the implications for polar wildlife, and the global climate change impacts.

You can read more about the Stability of the West Antarctic ice sheet in a warming world by Ian Joughin and Richard B. Alley, published 24 July 2011 in Nature Geoscience (doi:10.1038/ngeo1194)

An informative article on Earthsky by Dr Sophie Nowicki explains the concern with the Pine Island Glacier discharging ice from the West Antarctic Ice Sheet - Sophie Nowicki on weak underbelly of West Antarctic Ice Sheet

The following video, compiled by NASA/Goddard Space Flight Center Scientific Visualization Studio, shows glacier flow rates in the Amundsen Sea Embayment of West Antarctica accelerating and large changes in elevation occurring for the Thwaites, Pine Island and Smith glaciers.

Caption: This animation shows glacier changes detected by ATM, ICESat and ice bridge data in the highly dynamic Amundsen Embayment of West Antarctica. We know that ice speeds in this area have increased dramatically from the late 1990s to the present as the ice shelves in this area have thinned and the bottom of the ice has lost contact with the bed beneath. As the ice has accelerated, ice upstream of the coast must be stretched more vigorously, causing it to thin. NASA-sponsored aircraft missions first measured the ice surface height in this region in 2002, followed by ICESat data between 2002 and 2009. Ice Bridge aircraft have measured further surface heights in 2009 and 2010, and these measurements continue today. Integrating these altimetry sources allows us to estimate surface height changes throughout the drainage regions of the most important glaciers in the region.

We see large elevation changes at the coast on Thwaites glacier, at the center of the images, and large and accelerating elevation changes extending inland from the coast on Pine Island and Smith glaciers, to the left and right of the images, respectively. The changes on Pine Island and Smith glaciers mark these as potential continuing sources of ice to the sea, and they have been surveyed in 2011 by Ice Bridge aircraft and targeted for repeat measurements in coming years.

The scary part is that countries are already starting to quietly jostle for position for influence in the possible exploitation of Antarctic mining and biomass resources when the Protocol on Environmental Protection to the Antarctic Treaty comes up for review in 2041, fifty years after it came into effect in 1991. At the moment the environmental protocol of the treaty forbids "any activity relating to mineral resources, other than scientific research". But that doesn't stop the various nation states making claims and establishing bases and research facilities to position their influence on the future of Antarctica. Read Andrew Darby's 2010 article on China flags its Antarctic intent.