Quote:
Originally Posted by timshatz  My suggestion is to be a very critical thinker. Ask questions. If the question isn't answered, call...."BULLSHIT"! Don't have to be loud, but you do need to be persistant. |
From the Toronto Star a major newspaper yesterday
TheStar.com | News | The glaciologist's worst nightmare
There was a line in the Intergovernmental Panel on Climate Change (IPCC)'s fourth report that didn't get the attention it deserved:
"Dynamic processes related to ice flow not included in present models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea-level rise."
The media picked up on the projected rise in sea levels of 18 to 59 centimetres by the end of the century, but they didn't question the models' limitations.
Many climatologists fear the gradual melting of ice will be replaced by ice break-up, causing a sudden huge rise in sea level. Such a scenario increases the necessity of rescuing our climate.
But there is a gulf between this urgent need and the negotiations on a post-Kyoto treaty, to be submitted to the UN conference in Poland this month, and Copenhagen in December 2009. The lives of millions of people, mainly in the South, are at stake.
Lakes of melted ice form on the surface of the polar ice caps in the summer months, driving cracks down through the ice, creating conduits. In Greenland recently, one such lake, three kilometres wide, emptied like a draining bathtub in just 90 minutes.
So much water surging down to the bedrock of the ice sheet could contribute to massive icebergs breaking off and sliding into the sea – causing a sharp rise in sea level. It's the glaciologist's worst nightmare.
These "dynamic processes" have been observed for several years in the Arctic, where the Greenland ice sheet contains enough water to raise the oceans by six metres. But now the Antarctic is causing concern. Its glacial areas are made up of four elements: the east and west Antarctic ice sheets, the Antarctic peninsula, and the ice shelves that float on the ocean.
If the eastern ice sheet were to disappear, the oceans would rise by no less than 50 metres. Luckily, for now, it is stable. But ice is melting rapidly on the west coast of the peninsula, where the rise in temperature – three degrees in 50 years – is greater than anywhere else on the planet. In the northeast, the average summer temperature reaches 2.2 degrees C, with an expected 0.5 C warming per decade.
The Antarctic peninsula and the west Antarctic ice sheet each contain enough water to raise sea level by five metres. Two things increase the danger: The mountain valleys of the peninsula are less narrow and winding than those of Greenland, meaning glaciers could slide more quickly into the sea; and the speed of some ice floes has tripled in the past few years.
But also, the bedrock beneath the west Antarctic ice sheet lies mainly below sea level, and in several places slopes downward to the open sea. Experts are worried that the circumpolar current, which is getting warmer and gradually approaching the coast, could cause the underwater anchor of the ice sheet to melt.
The danger is closer than we think, according to James Hansen, director of the Goddard Institute for Space Studies at NASA, and eight other experts who all put their names to an article on this subject in the journal Science.
Their conclusions follow paleoclimatic research. Sixty-five million years ago, Earth had almost no ice. The Antarctic became glaciated around 35 million years ago, when a combination of solar rays, the albedo (reflectivity), and the atmospheric concentration of greenhouse gases reached a tipping point, creating the conditions for cooling.
Sea levels fell, and precipitation, in the form of snow, increased at the poles. The authors say we are about to reach that same tipping point, but from the other direction.
This warning must be taken seriously. The IPCC's estimate on ocean-level rise is, in fact, the least precise of its projections: From 1990-2006, sea level rose by 3.3 mm a year, while the estimate was 2 mm.
The difference – 60 per cent – could be down to the difficulty in modelling the behaviour of glaciers. If temperature rise were stabilized at 2 C above 1780 levels (the end of the pre-industrial era), the models project a sea-level rise of between 0.4 and 1.4 m in a few centuries.
A differential of 60 per cent would be enough to bring that up to between 0.6 and 2.2 m. (These figures are probably an underestimate, since ice sheets break up in a non-linear way.)
This changes the timescale completely: If Hansen and colleagues are correct, an irreversible catastrophe could take place within a few decades.
One metre of sea-level rise would endanger the lives of tens of millions of people. Ten million Egyptians, 30 million Bengalis, and a quarter of Vietnam's population would have to leave their homes; London and New York would be under threat.
The IPCC president, Rajendra Pachauri, described a "frightening situation" and spoke of his hope that "the next report ... will be able to provide much better information on the possibility of these two large bodies of ice (Greenland and the West Antarctic ice sheet) melting."
Unfortunately, this report will not come out until 2013 – too late to influence this month's and next December's negotiations on a post-Kyoto strategy.
The IPCC's underestimate of sea-level rise is all the more unfortunate since its projections, approved by governments, form the basis of the climate-change negotiations begun in Bali in December 2007. What's worse, politicians always downplay these predictions.
While scientists' concerns grow, those in power increase their rhetoric but limit their targets to the most conservative predictions. The North relies on "flexible mechanisms" in an attempt to limit its effort to voluntary reductions.
This was the policy put forward by Nicholas Stern, former chief economist at the World Bank. In his 2006 report to the British government, he said, "The lesson here is to avoid doing too much too fast" because "great uncertainty remains as to the costs of very deep reductions ... of 60 to 80 per cent or more ... from industrial processes, aviation and a number of areas."
The worry is that climate negotiations, if they lead anywhere, will lead to targets determined by profit, rather than the protection of people and the safety of the planet.
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