As we have long since acknowledged, this past decade has been a warm decade in the run of things. The prior two decades showed a warming trend while this present decade saw that trend fully developed and a flattening out at its high. The past two years has seen precipitous decline suggesting that the warm decade may be over. This could be a response to the accelerated warming of 2007 or the commencement of a decadal downtrend and my bet is presently on the latter.
In the meantime, according to these reported numbers, we have added one inch or so to ocean over that period. That is too big to be a mistake so it gives us a magnitude for global response to a rise in temperature. According to this it has mostly come from the Greenland sheet which fits observations. It seems a bit rich, but is obviously not.
And yes, if this were to continue at this present temperature range it is plausible to anticipate an inch of rise per decade until the Greenland sheet is eliminated. Of course, Mother Nature is already signaling the opposite.
It seems though that two cold winters notwithstanding that the sea ice retreat is as quick as the past two years, suggesting that it takes a bit more than a simple drop in average temperatures. We also understand a bit better, reports of access during the Viking era. Once the bulk of the sea ice is reduced, the lower level remains quite stable in the face of colder weather.
That suggests that a simple repeat of 2007 every decade or so will progressively reduce the ice pack. It also suggests that historic conditions were a direct and unusual result of the little ice age itself and are not to be considered the natural default. So unless the little ice age comes back we can expect Greenland to get back in the dairy business and the Northwest Passage will continue to open every summer.
I suggest that we are living through the restoration of normal climatic conditions that will be similar to the medieval optimum and this will last until perhaps something goes bang in Alaska.
As an aside, the language of this item is intemperate at best and the numbers and claimed facts are been exaggerated right across the board. However 3.1 mm per year over a decade is a believable number since it is easy to construct accurate enough tidal gauges and the like in enough places to be so assured.
Oceans Rising Faster Than UN Forecast, Scientists Say (Update2)
By Alex Morales
June 18 (Bloomberg) -- Polar ice caps are melting faster and oceans are rising more than the United Nations projected just two years ago, 10 universities said in a report suggesting that climate change has been underestimated.
Global sea levels will climb a meter (39 inches) by 2100, 69 percent more than the most dire forecast made in 2007 by the UN’s climate panel, according to the study released today in Brussels. The forecast was based on new findings, including that Greenland’s ice sheet is losing 179 billion tons of ice a year.
“We have to act immediately and we have to act strongly,” Hans Joachim Schellnhuber, director of Germany’s Potsdam Institute for Climate Impact Research, told reporters in the Belgian capital. “Time is clearly running out.”
In six months, negotiators from 192 nations will meet in Copenhagen to broker a new treaty to fight global warming by limiting the release of greenhouse gases from burning fossil fuels and clearing forests.
“A lukewarm agreement” in the Danish capital “is not only inexcusable, it would be reckless,” Schellnhuber said.
Fossil-fuel combustion in the world’s power plants, vehicles and heaters alone released 31.5 billion metric tons of carbon dioxide, the main greenhouse gas, 1.8 percent more than in 2007, according to calculations from BP Plc data.
‘Rapid and Drastic’
The scientists today portrayed a more ominous scenario than outlined in 2007 by the UN Intergovernmental Panel on Climate Change, which likewise blamed humans for global warming. “Rapid and drastic” cuts in the output of heat-trapping gases are needed to avert “serious climate impacts,” the report said.
The report called for coordinated, “rapid and sustained” global efforts to contain rising temperatures. Danish Prime Minister Lars Loekke Rasmussen, also in Brussels, told reporters that nations have to reverse the rising trend in emissions of heat-trapping gases.
“We need targets,” Rasmussen said. “All of us are moving toward the same ambitious goals.”
Scientists from institutions including Yale University, the University of Oxford and the University of Cambridge compiled the 39-page report from research carried out since 2005, the cutoff date for consideration by the IPCC for its forecasts published in November 2007.
Ocean levels have been rising by 3.1 millimeters a year since 2000, a rate that’s predicted to grow, according to the study. The projections of sea levels rising by a meter this century compare with the 18 to 59 centimeters (7 to 23 inches) forecast by the IPCC.
“There are indications that rates of sea-level rise are higher than projected, and impacts like Arctic melting are more rapid,” Martin Parry, who supervised part of the UN panel’s 2007 study, said in a telephone interview. He wasn’t involved in writing the new report.
Oceans are warming 50 percent faster than the IPCC predicted and Arctic sea ice is disappearing more rapidly in summer -- exposing darker ocean that absorbs more heat, the study said.
The academics produced the study, “Climate Change --Global Risks, Challenges and Decisions,” by compiling research submitted to a conference in Copenhagen in March. They also drew from an October 2006 report into the economics of climate change by Nicholas Stern, then the U.K. government’s chief economist.
Stern’s study, which wasn’t included in the IPCC report, said that the cost of avoiding the worst impacts of climate change can be limited to 1 percent of economic output while doing nothing could lead to damage costing as much as 20 percent of the world’s gross domestic product.
“Greater near-term emissions lock us into greater climate change requiring greater costs from climate impacts and more investment in adaptation,” Stern wrote in today’s study. “Furthermore, they lead to a faster rate of climate change with greater challenges for adaptation.”
By 2050, when the global population will be an estimated 9 billion people, per-capita gas emissions will need to have fallen to about 2 tons a year, compared with levels as high as 20 tons a person currently in the U.S., the report proposed.
The University of Copenhagen coordinated the effort by the 10-school International Alliance of Research Universities. Other members include the University of California at Berkeley, Peking University, the Australian National University, ETH Zurich, the National University of Singapore and the University of Tokyo.
To contact the reporter on this story: Alex Morales in London at: