Improvement in simulation of Eurasian winter climate variability Dec 2012 gives some sense of the problems with the sea ice models
As the first image here shows, the sea ice computer models are far from being able to project the rate of sea ice loss. Even so they are being relied on.
Sea ice computer models have a history going back decades
The IPCC AR5 WG1 SPM, for our current worst case emissions scenario, reports that 'Based on an assessment of the subset of models that most closely reproduce the climatological mean state and 1979 to 2012 trend of the Arctic sea ice extent, a nearly ice-free Arctic Ocean19 in September before mid-century is likely for RCP8.5'
Hoeve some modls have projected as early as 2020. ''...some showing a nearly ice-free state as early as 2020... ( J. Stroeve Trends in Arctic sea ice extent.. 2012)
It is crucial for climate change mitigatio that we do not allow the Arctic summer sea ice to disappear and therefore any model that is relied must be accurate.
Why Predicting Sea Ice Cover Is So Difficult ( Nat Geo July 2013) gives the latest 2013 sea ice model published projection which is predicted to be 2054-2058, with amazing apparent precision. The article also provides all the large gaps in the modeling, on which basis the ice could be gone muich earlier.
Direct measurement of Arctic sea ice from real time monitoring is from Professor Peter Wadhams by UK navy submarine sonar and the 2009 Catlin Survey.
Even the satellites have not provided reliable readings in sea ice extent and scientists in general have been relying on their computer modeling- '.
With the 2012 record low collapse of the sea ice we know the models are in error to an extreme and dangerous degree to guide the climate science and policy.
The NAP has a 2012 comprehensive review on sea ice modeling .. predictions of Arctic sea ice'.
Like climate change models in general many models do not project an abrupt decline like happened in 2007 but M Holland says Faster rates of decline and a potential for abrupt
changes in September sea ice are simulated by many of the better Arctic models. Just over half the IPCC sea ice models projected a possibility of abrupt decline.
However even after the 2012 sea ice collapse the experts cannot agree, with most still sticking to their seas extent models even though they fail to project the actual rate of extent decline. Only the US Navy's W. Maslowski has a model that includes seas ice volume and it projects an ice free Arctic in a few years not a few more decades.
The 2007 IPCC recorded models projected range for the start of an ice free Arctic is 2050 to well beyond 2100. The large record summer sea ice in 2007 caught the sea ice modeling scientists completely by surprise. Research by NSIDC have found observations proved the sea ice decline to be 30 years ahead of the decline projected by the models.
The models simulated a loss in September ice cover of 2.5 percent per decade from 1953 to 2006. September marks the yearly minimum of sea ice in the Arctic. But data sets, blending aircraft and ship reports with satellite measurements, show that the September ice actually declined at a rate of about 7.8 percent per decade during the 1953 to 2006 period - three times larger than the mean from the computer models (Arctic sea ice decline: Faster than forecast Stroeve et al 2007)
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