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IPCC On Antarctic Sea Ice

October 1, 2013

By Paul Homewood



The newly released IPCC Fifth Assessment Report has a few things to say about the increasing Antarctic sea ice extent:-


1) Available evidence precludes us from making robust statements about overall changes in Antarctic sea ice and their causes.


2)There has been a small but significant increase in total ice extent of 1.5% per decade between 1979 and 2012, and a greater increase in ice area, indicating an increase in concentration.


3) The observed upward trend in Antarctic sea ice extent is found to be inconsistent with internal variability based on the residuals from a linear trend fitted to the observations, though this approach could underestimate multi-decadal variability.


4) The CMIP5 simulations [i.e climate models] on average simulate a decrease in Antarctic sea ice extent though Turner et al. (2013) find that approximately 10% of CMIP5 simulations exhibit an increasing trend in Antarctic sea ice extent larger than observed over the 1979-2005 period. However, Antarctic sea ice extent variability appears on average to be too large in the CMIP5 models (Turner et al., 2013; Zunz et al., 2013)


In other words, their models forecast less ice, and they cannot explain why there is instead more ice. The fact that area is increasing even faster would suggest that the increase in extent is not due to winds spreading the ice out.


Perhaps some of the naive SkS denizens might care to take note, before they embarrass themselves again with their wacky theories.

  1. John F. Hultquist permalink
    October 1, 2013 4:32 pm

    I’m reminded of . . .
    “Houston, we have a problem.”

    Does the IPCC have a central headquarters (Geneva ?) or is it a floating thing from one warm exotic locale to the next?

    “Geneva, we have a problem.
    No, we don’t think duct tape will help.
    It’s ice. We don’t know how it got here.
    We need heat. Send heat.

    It’s missing! What the . . .”

  2. October 1, 2013 8:52 pm

    The increasing extent of antarctic ice cover is not surprising. I have recently looked at long-term temperature trends at 13 antarctic stations and find that temperature trends have been virtually zero over the past 50-60 years at ten of these stations. Three stations located in the more northerly Antarctic Peninsula do indicate increasing temperatures.

    Of course other factors may also influence the extent of ice cover – such as precipitation, ocean currents and wind. But surely surface temperature observations would be expected to be highly correlated to the extent of ice cover.

  3. Brian H permalink
    October 2, 2013 6:00 am

    Which particular model failures account for the blown Antarctic ice forecasts? Let me count the ways …


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