Antarctic confusion
Sep 18, 2014
Bishop Hill in Climate: Surface

With the sea ice in Antarctica breaking extent records again this week, New Scientist seems to have taken it upon itself to engage in a bit of damage limitation on behalf of the global warming movement. Its article today declares that the growth in sea ice is in fact caused by global warming (who would have thought it?!). 

There doesn’t actually seem to be any research to back this up – there is no link to a new paper or anything like that. We just have a couple of talking heads with a rather impenetrable explanation of their case:

More sea ice may seem odd in a warmer world, but new records are expected every few years, says Jan Lieser of the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart. That's because the southern hemisphere warms more slowly than the north, as it has less landmass, boosting the winds that circle Antarctica and pulling cold air onto the sea ice.

And if that explanation were not confusing enough, the link at the end of the paragraph is to a 2009 New Scientist article about a paper by Turner et al that has a completely different explanation for the rise in sea ice:

The autumn increase in [sea ice] is primarily a result of stronger cyclonic atmospheric flow over the Amundsen Sea. Model experiments suggest that the trend towards stronger cyclonic circulation is mainly a result of stratospheric ozone depletion, which has strengthened autumn wind speeds around the continent…

The confusion is further increased when we learn from Turner et al that the rise in Antarctic sea ice is statistically significant (I doubt it, given how short the time series is) and then just a few sentences later we learn that “statistics derived from a climate model control run suggest that the observed sea ice increase might still be within the range of natural climate variability.” This suggests to me that either the climate model or the statistical model used are nonsense. Or perhaps both.

So is the sea ice extent significant or not? Is it something to do with warming or with ozone? It’s anyone’s guess.

[Interestingly, a similar story appears in the Guardian, with  Lieser appearing once again. So any impression you might have got that this is a public relations exercise, rather than news, was entirely correct]

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