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Gravesend – further up the river than we originally thought?
These are the very disappointing results of new analyses posted here at Sciencedaily
New research suggests that ocean temperature and associated sea level increases between 1961 and 2003 were 50 percent larger than estimated in the 2007 Intergovernmental Panel on Climate Change report. An international team of researchers, including Lawrence Livermore National Laboratory climate scientist Peter Gleckler, compared climate models with improved observations that show sea levels rose by 1.5 millimeters (sic) per year in the period from 1961-2003. That equates to an approximately 2½-inch increase in ocean levels in a 42-year span.
The ocean warming and thermal expansion rates are more than 50 percent larger than previous estimates for the upper 300 meters of oceans. The research corrected for small but systematic biases recently discovered in the global ocean observing system, and uses statistical techniques that “infill” information in data-sparse regions. The results increase scientists’ confidence in ocean observations and further demonstrate that climate models simulate ocean temperature variability more realistically than previously thought.
“This is important for the climate modeling community because it demonstrates that the climate models used for assessing sea-level (sic) rise and ocean warming tie in closely with the observed results,” Gleckler said.
The results are reported in the June 19 edition of the journal Nature.
Climate model data were analyzed from 13 different modeling (sic) groups. All model data were obtained from the WCRP CMIP3 multi-model dataset archived at the LLNL’s Program for Climate Model Diagnosis and Intercomparison (PCMDI).
Although observations and models confirm that recent warming is greatest in the upper ocean, there are widespread observations of warming deeper than 700 meters (sic). Results were compared with recent estimates of other contributions to sea level rise including glaciers, ice caps, Greenland and Antarctic ice sheets, and thermal expansion changes in the deep ocean. When these independent lines of evidence are examined collectively, the story is more consistent than found in earlier studies.
The oceans store more than 90 percent of the heat in the Earth’s climate system and act as a temporary buffer against the effects of climate change. The ocean warming and thermal expansion rates are 50 percent larger than previous estimates for the upper 700 meters of oceans, and greater than that for the upper 300 meters.
“This is just the tip of the iceberg, so to speak,” Gleckler said. “Our ability to quantify structural uncertainties in observationally based estimates is critically important. This study represents important progress.”
The team involved researchers from the Centre for Australian Weather and Climate Research (CSIRO), the Antarctic Climate and Ecosystems Cooperative Research Centre and LLNL.
So, sea level rises are worse than initially thought. That is most worrying given that so much of our infrastructure is on the coasts of our countries and that so many of our people live on the coastal flood-plains. Now consider this which was reported back in February 2002 at Sciencedaily
New calculations by a University of Colorado at Boulder researcher indicate global sea levels likely will rise more by the end of this century than predictions made by the Intergovernmental Panel on Climate Change in 2001. The projected sea-level rise is due to a revised estimate of the ice melt from glaciers, said geological sciences Emeritus Professor Mark Meier.
Meier and CU-Boulder colleague Mark Dyurgerov have collected new data showing the world’s glaciers and ice caps have exhibited significant ice loss in the 20th century, which has accelerated since 1988. That loss has contributed to at least 20 percent of the observed rise in sea level, said Meier.
"Some glaciers around the world now are smaller than they have been in the last several thousand years," he said.
"The rate of ice loss since 1988 has more than doubled," said Meier, a researcher and former director of CU-Boulder’s Institute for Arctic and Alpine Research. Dyurgerov also is an INSTAAR researcher.
Meier said the IPCC report might have underestimated the wastage of glaciers and ice caps around the word -- excluding Greenland and Antarctica -- for several reasons. The IPPC did not include increases in ice wastage since the late 1980s, an apparent increase in the sensitivity of ice wastage to both temperature and precipitation, and a probable increase in melting from small, cold glaciers surrounding the Greenland and Antarctic ice sheets, he said.
In addition, new data from colleagues at the University of Alaska show that huge glaciers on the West Coast of Alaska and northern Canada are wasting rapidly, said Meier. The melting of these large glaciers has contributed roughly 0.14 millimeters per year in sea rise over the long-term, according to calculations by Meier and Dyurgerov, jumping to more than 0.32 millimeters per year during the last decade.
The IPCC, which estimated global ice wastage of only 0.3 millimeters per year, probably underestimated the contribution of glacier disintegration to sea-level rise because little data on the large, maritime glaciers in Alaska was available, said Meier. But this region is the largest contributor to sea-level rise, he said.
"The sensitivity of glacier melt to temperature rise depends largely on precipitation, which in some ‘glaciered’ areas like southern coastal Alaska has been greatly under-measured," said Meier. "The large glaciers of Alaska and adjacent Canada currently are contributing about half of the rate of global ice loss, exclusive of Greenland and Antarctic ice sheets," said Meier. "But they contain only 17 percent of the glacier ice area."
The new data suggests the IPCC calculation for the 21st century -- a total of 0.16 to 0.36 feet -- was an underestimate, said Meier. He calculated that glacier melting could contribute 0.65 feet or more to sea level this century.
The IPCC estimated that other processes such as ocean warming would cause an additional 0.36 feet to 1.4 feet of sea-level rise by the year 2100, Meier said.
"These estimates in sea-level rise may seem small, but a 1-foot rise in sea level typically will cause a retreat of shoreline of 100 feet or more, which would have substantial social and economic impacts," Meier said. (My emphasis in bold).
Meier said that in the United States, some large coastal cities like Houston "are not much above sea level now." He also said island nations such as Seychelles off the West Coast of Africa and Kiribati southwest of Hawaii are within a meter of being inundated by sea rise.
In addition, sea rise of only 1 meter (sic) in Bangladesh would put one-half of the nation underwater, displacing more than 100 million people.
Now, back in 2002 we guessed that shoreline retreat was going to be in the order of 100 feet or more with what we had been able to ascertain then. How much worse is it really going to be in the light of what we have been able to work out what now are the more accurate figures for the projected sea level rise.
Before you all start yelling just remember this – there is not a single sea level observatory anywhere on Earth which disagrees with the figures – it’s happening and it’s happening fast.
Some, a very few, glaciologists believe that there is a possibility that slippage into the oceans of some major ice-sheets could happen catastrophically quickly – in years rather than decades – and raise sea levels by some thirty to forty metres world-wide within ten to twenty years if such an event were to take place. Specifically, they are looking at the unstable East and West Greenland ice-sheets. Most glaciologists don’t think, at the moment, that this is likely but they do not altogether discount the possibility: the role of melt water under pressure under the ice sheets is very little understood and could prove to be crucial in our understanding of how glaciers react to global warming.
But, as figures are revised and as new data comes to hand from satellite and on site surveys, and as new understandings of the dynamics of glacier slippage are discovered, just how much credence can we place on the current figures being final and correct? Very little, I’d say.
However, the real point is for us is that a very small rise in sea levels is going to precipitate a major population shift. Given that our liberal free democracies are already under pressure from illiberal elements which have migrated here under very little pressure to do so, then how much greater is going to be the threat to our freedoms when faced with hordes of displaced persons for whom we will naturally feel some degree of sympathy but whose collective social and religious focus is shariah and Islam, for we, and our technically competent societies, are more likely to find solutions and to survive than theirs are, so, naturally, we are going to be the destination of choice for those people who are wealthy enough, or able enough, to flee from the disaster as it slowly engulfs their under-developed countries.
Global warming, whether anthropogenic or natural, is not just an economic question, it is also a survival question. It’s a test of our will to believe that we should be compassionate and to act compassionately, but it is also a test of our will to survive as free peoples.
It puts a whole new meaning on ‘turning the tide’, doesn’t it?