The Mammoth in the Freezer: Sea Level Rises

The mammoth in the freezer

While various factions debate the causes of global warming we’re all in danger of ignoring its undeniable and rapidly accelerating effects. Policy makers regard official projections on sea-level rise as exaggeration, but the figures have been understated, argues John Collee…

 

Scientists are, by their nature, conservative creatures. A single unfounded claim can forfeit their credibility and professional reputation for life.So it's not surprising that, in order to avoid any accusations of bias, members of the Nobel prize-winning Intergovernmental Panel on Climate Change have taken pains to avoid making claims that may seem exaggerated or alarmist.

IPCC wording is routinely thrashed out by committees and subcommittees until anything that may be remotely construed as environmentalist propaganda has been expunged from the text. Thus, even though the panel's examination of global climate began in the '80s, it was not until the second report in 1995 that the authors claimed "the balance of evidence suggests a discernible human influence on global warming".Even this modest statement, based on 15 years of fairly sound evidence, was considered too strong by the oil and coal lobbies. 

Dr Ben Santer, the lead author of that chapter, was accused of scientific fraud in The Wall Street Journal and called before the US Senate to justify himself. Santer was vindicated, but his story gives you an idea of how high are the stakes and how dirty the fighting can get.So never let it be said the IPCC is a coalition of unaccountable hotheads given to wild overstatement.On the contrary, its ranks include many scientists who believe that the panel routinely understates the dangers we face.

The problem is compounded by the IPCC being such a huge organisation, subject to so many internal checks and balances. With nearly 4000 authors, contributors and reviewers in more than 130 countries, submissions cannot be reviewed unless received a year in advance. The Fourth (2007) IPCC Report includes nothing more recent than papers published before July 2006, detailing research often completed in 2005.

 

So governments are forming policy in 2009 based on data more than four years old. The next IPCC report will not be available until 2013.

For a problem advancing at warp speed, this process is far too ponderous. The 2007 report's projections for Artic ice melt were questionable the year they were published. Based on 2005 data, they predicted Arctic sea ice would survive until century's end, but satellite observations in September 2006 and 2007 revealed a much steeper trajectory of decline than anyone predicted. 

While it is dangerous to extrapolate from the current steep line of descent, it's valid to ask what this says about other IPCC predictions, on sea level rise for example.Sea ice is floating ice. When it melts, sea levels are largely unaffected. Land-based ice does raise sea levels, but in the vast and hostile terrain of the Greenland ice sheet the exact degree of melting is difficult to measure.In 2005, when the latest IPCC report was being assembled, there was relatively little data and no reliable computer models for the behaviour of the land-based Greenland ice sheet. Changes were certainly happening: surface melting, ice earthquakes, increased glacier flow rates. 

But no one could reliably offer a prediction of the speed and extent of changes over the whole ice sheet.Ice-sheet dynamics are immensely complex, but you witness the thawing process at its simplest whenever you defrost the freezer.When temperatures first rise, nothing much seems to happen. In the second phase, melting becomes visible on the surface, and this surface water causes much more ice to liquefy. In the third phase this melt water tracks through the solid ice, finally producing a honeycomb of chasms and passages. In the fourth phase the whole fragile structure collapses and floods the kitchen floor.

That rather facile model is greatly affected by Greenland's scale, altitude and topography, but it is now almost certain that this "wet process" was underestimated in IPCC's fourth report. Late in 2006, as conservative ice-melt figures were being prepared for publication, Arctic field workers on the margins of Greenland were already reporting vast "moulins" of meltwater pouring down crevasses in the Greenland glaciers, lubricating the rock underneath and hastening glacier flow.How these factors affect ice loss is open to question, but the proof of serious loss of ice globally lies in the satellite data. In 2007 James Hansen of NASA's Goddard institute wrote that ice sheets on Greenland and Antarctica were diminishing by about 150 cubic kilometres a year - at least double the rates of several years ago.

Hansen added: "I find it almost inconceivable that 'business as usual' will not result in a rise in sea level measured in metres within a century."His logic went like this: sea level rise is now 3.1 millimetres a year. Allowing for the rise due to thermal expansion of water (warm water takes up more space than cold water), we can say that at least 1 millimetre a year (1 centimetre a decade) is due to melting ice. 

That component has approximately doubled in the past decade.If you apply a constant forcing (in this case, temperature rise), then, after overcoming inertia, you create a constant acceleration. One might therefore expect the doubling to continue; a centimetre this decade, plus two centimetres next, plus four, plus eight, plus 16, plus 32 and so on would make five metres by the end of the century.It is currently debatable whether things could get that bad.

High-altitude ice is relatively stable and is augmented by new snowfall. There may be physical barriers blocking potential ice flow down to the lower levels where thawing is most rapid. This was detailed in a paper last year by Tad Pfeffer and colleagues at the University of Colorado, who predicted sea level rises of 0.8 to two metres by the end of the century. They favoured the lower estimate, which was nonetheless over the maximum projected by the IPCC.Hansen is convinced that two metres is the minimum sea-level rise we can expect this century if we carry on business as usual. He says the most recent studies post-date the Pfeffer findings and seem to confirm the two-metre-plus projections.

 

This is serious. A rise of just 25 centimetres would result in many millions of environmental refugees. A rise of 1 metre would erode up to 100 metres inshore. Half a metre, plus storm surges, would threaten many populous cities - Manhattan, London, Bangkok, Singapore. With Australians moving en masse to the coast, we should factor the new sea-level data into our planning decisions now.

Three other conclusions arise from all this. International climate experts need to find a way of reviewing and delivering more up-to-date information. It is hard enough to get policy makers to set targets, more so when they cannot see how fast the goalposts are moving. Secondly, we need to pressure politicians to quit taking baby steps and start making hard decisions for a carbon neutral future. 

A 25 per cent cut in carbon dioxide emissions between 2000 and 2020 is being sold to us as a cause for celebration, but it is about half what we need if the figures are properly addressed. A huge amount could be achieved short-term if Canberra [or insert your local Capital - Ed] listened to energy-efficiency experts rather than oil and coal lobbyists.Thirdly, if our politicians will not confront the full horror of these calculations, we must do some confronting ourselves.We all need to be far better educated on climate change, and we need to get much better at spreading the message in TV ads, billboards and internet campaigns.Scientists are conservative and lack the money and resources to advertise their point of view.

Expecting them to beat the coal lobby in [your nation’s capital] is like sending two men in a [tin rowboat] to disarm North Korea.If we stopped emitting carbon dioxide tomorrow we would still be committed to twice the global warming, which is now shrinking the Arctic sea ice at a wholesale rate. 

We need radical immediate action and, yet, we seem gripped with the strange numb complacency that characterised the world before the last great global convulsion in 1939.I have a nightmare vision of [Australian Prime Monster] Kevin Rudd returning from the Copenhagen climate summit in December, congratulating himself on having nailed our emission cuts to 10 or 20 per cent - figures that will have not the slightest impact on the coming terrible catastrophe.I fear that it will be Rudd's legacy to history, like the British prime minister Neville Chamberlain with his useless truce agreement: "I have in my hand a piece of paper …", deaf to the words of Churchill (and, more recently, Al Gore): 

"The era of procrastination, of half-measures, of soothing and baffling expedients, of delays, is coming to a close. In its place, we are entering a period of consequences."

 

June 6, 2009

images - http://www.wildwildweather.com/forecastblog/wp-content/uploads/2008/09/700px-recent_sea_level_rise.png

http://vrstudio.buffalo.edu/~depape/warming/europeMap.jpg

http://vrstudio.buffalo.edu/~depape/warming/americaMap.jpg

John Collee is a Sydney writer.

From the Sydney Morning Herald - http://www.smh.com.au/environment/global-warming/the-mammoth-in-the-freezer-20090605-byhl.html?page=-1

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