In an interview on Australian ABC Television program, The 7.30 Report, James Hansen, a prominent NASA climatologist, predicted the likelihood that the earth will pass a tipping point resulting in Sea Level Rise of up to a metre every 20 years. The trigger for this is an extra degree of global warming resulting in the runaway melting of the Greenland and West Antarctic Ice sheets.
According to Hansen "the problem is that the climate system in general has a lot of inertia and that means that it takes time for the changes to begin to occur but then, once they do get under way, it becomes very difficult to stop them and that is true in spades for the ice sheets. If we once begin to disintegrate it will become very difficult, if not impossible, to stop them and we are beginning to see now on both Greenland and west Antarctica disintegration of those ice sheets. They're both losing ice at a rate of about 150 cubic kilometres per year and that's still not a huge sea level rise."
"Sea level rise is now going up about 3.5 centimetres per decade. So that's more than double what it was 50 years ago. But it's still not disastrous; it's a problem, but it's not disastrous. But the potential is for a much larger sea level rise. If we get warming of two or three degrees Celsius, then I would expect that both West Antarctica and parts of Greenland would end up in the ocean, and the last time we had an ice sheet disintegrate, sea level went up at a rate of 5 metres in a century, or one metre every 20 years. That is a real disaster, and that's what we have to avoid." said James Hansen to 7.30 Report anchorman Kerry O'Brien.
The current International Panel on Climate Change (IPCC) preliminary report released in February 2007 predicted a global average temperature rise of 1.8 to 5 degrees by 2100. For sea levels it predicted a rise of 17.8 centimetres to 58.4 centimetres by the end of the century. The report says an additional rise between 9.9 to 19.8 centimetres is possible due to continued melting of polar ice sheets.
Hansen said that "where the current IPCC report is going to suggest smaller numbers than the last report, although all of the information that we're getting in the last year or two points in a very much different direction. Now, in defence of IPCC, their procedure required that they stop getting new inputs more than a year ago and a lot of the data on ice sheet stability has come up in just the last year or two."
To a question from O'Brien on constraints on communication between scientists and the public, Hansen replied "Well, it worries me a lot because in our country the government science agencies have public affairs offices which are now staffed with political appointees and those political appointees have a big impact on what science gets reported and how it's reported. And I'm very disturbed about that. I think that public affairs officials should be helping scientists speak in a language that the public can understand but they shouldn't be massaging the information. And the other example is reporting, testifying to Congress. I don't understand why a scientist's testimony has to be approved by the White House. Government scientists are paid by the public, paid by taxes and I think we're working for the public and for Congress, as well as for the executive branch, and I don't think that our testimony should be filtered."
Hansen also called for a moratorium on building new coal fired power stations until the technology was available to sequester carbon dioxide emissions underground in 5 to 10 years, and the necessity to plan for the demolition of existing coal fired power plants. "In the meantime, we should be emphasising energy efficiency so that we don't need new old style coal fired power plants. We're just not doing that. Buildings could be 50 per cent more efficient. The architects and engineers will tell you they have the technology to do that, but if it's not required it's not likely to happen." he told Kerry O'Brien.
Barrie Pittock, former head of the CSIRO and a contributor to the IPCC report, said on the 7.30 Report: "We have an increase in the outflow of glaciers from Greenland and parts of Antarctica already that have been observed. The latest papers suggest a rise by 2100 between about 50 centimetres and 1.5 metres, which is quite a lot more than the IPCC report."
Barrie Pittock said that there is a crude rule of thumb measurement of the effect of sea level rise which applies theoretically just to any straight sandy beach, which suggests for every metre rise in sea level the coastline will retreat or go inland by 100m.
In Hobart, in the Australian state of Tasmania this week (March 12-15) a conference of about 200 scientists met to discuss oceanography, including Sea Level Rise and ongoing monitoring of the earth's oceans. Much of the accurate measurement data is collected from the Jason 1 satellite. Satellite measurements suggest that global warming is doubling the number of intense storms and coastal flooding on the West and East Australian coasts, and the rate of sea level rise is being severely underestimated by the IPCC recent report.
Most climate models have factored Ice Sheet melting as a relatively slow process, but according to recent observations and research their melting is a dynamic effect that accelerates with time.
David Griffin from the CSIRO, an Australian Government funded research organisation, said that available data indicates that sea levels are rising faster than expected, and the main reason is climate change. His comments indicate a more accurate model is required to explain the rapid rate in sea level rise. "Well that underpins the importance to understand why the observed rate of sea-level rise is greater than the models can explain," he said. "We're relying on those models to make projections for the next 100 years. If they can't actually explain the last 10 years, then we know that we've got more work to do."
The head of NASA Oceanography, Eric Lindstrom, attending the conference, was reported by the ABC as saying that a lot of scientists are wondering when society will wake up to the seriousness of climate change. "I'd say the major force involved in these changes is human-induced climate change, global warming," he said. "I consider this data very serious and that there is climate change happening and that we need to be concerned about it."
To give an idea of the impact of even a moderate rise in sea levels, the Insurance Industry of Australia undertook a study in 2006, before most of the recent research on Ice Sheet melting, of the likely impact of rising sea levels, especially when compounded with King tides and storm surges. The study identified 700,000 buildings at risk nationwide around the coast of Australia from rising sea levels.
Karl Sullivan from the Insurance Council of Australia said "We're working closely with government to try to map and understand what those risks are as climate change starts, or what the exact details of climate change may be and how it may manifest." according to the ABC 7.30 Report.
According to 7.30 Report journalist Matt Peacock the Insurance report specifies that Sea Level Rise associated with King tides and storm surges may effect more than 700,000 buildings on the Australian coast. "In the Northern Territory nearly 900 coastal buildings, mainly in Darwin, are at risk. Along the Tasmanian coastline, more than 17,000 addresses are considered vulnerable. More than 60,000 in South Australia, mostly around Adelaide, and along the Victorian coast over 80,000, mainly around Melbourne. In Western Australia, 94,000 buildings have been identified around Perth, but the biggest concern is along the eastern seaboard; more than 200,000 buildings are considered vulnerable on the NSW coast, including Sydney. Queensland faces the largest risk, with almost 250,000 buildings under threat, stretching from the Gold Coast to the Sunshine Coast."
Sources:
* The 7.30 Report - ABC TV - 13 March 2007 - Scientist predicts disastrous sea level rise
http://www.abc.net.au/7.30/content/2007/s1870955.htm
* ABC News 12 March, 2007 - The CSIRO says sea levels are rising faster than expected
http://www.abc.net.au/news/newsitems/200703/s1869919.htm
* ABC News 12 March, 2007 - NASA official 'surprised' climate change still debated
http://www.abc.net.au/news/newsitems/200703/s1869676.htm
* The 7.30 Report - ABC TV - 12 March 2007 - Coastal areas face environmental threats
http://www.abc.net.au/7.30/content/2007/s1869888.htm
* PM - ABC Radio - 13 March 2007 - Global warming doubling number of intense storms
http://www.abc.net.au/pm/content/2007/s1870888.htm
* NASA - The Earth Observatory = June 2006 - The Rising Sea Level
http://earthobservatory.nasa.gov/IOTD/view.php?id=6638
