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Will Christopher Booker declare ‘Arctic sea ice recovering’ again?

• 03 Nov 2011, 15:00
• Verity Payne

The National Snow and Ice Data Center (NSIDC) have released their latest update on Arctic sea ice, which shows that October's sea ice extent was the second lowest since satellite records began. So, of course, we're wondering if climate skeptic columnist extraordinaire, Christopher Booker, is about to declare that the sea ice is recovering, perhaps before delivering a few choice comments about the great global warming 'scam'.

Why? Well, the NSIDC findings are illustrated in the graph below:

The NSIDC also notes that the annual autumn freeze-up is well underway, with sea ice growing back quickly, about 40 percent faster than the average rate for October 1979 - 2000:

"The rate of freeze-up depends on several factors including the atmospheric conditions and the amount of heat in the ocean that was accumulated during the summer."

The autumn/winter regrowth of Arctic sea ice is part of a seasonal cycle of sea ice growth and retreat. Much of the sea ice melts in the warm summer months and grows back in the cold winter months.

But this seasonal pattern should not be confused with an overall declining trend in sea ice extent. As the NSIDC put it:

"...Each decade, the October extent has started from a lower and lower point, with the record low extent during the 1980s (1984) substantially higher than the record low extent during the 1990s (1999), which in turn is substantially higher than the record low extent during the 2000s (2007)."

In previous years, commentators have misrepresented the annual autumn freeze-up as the Arctic sea ice 'recovering' from its declining trend. For example, Christopher Booker, in a 2008 Telegraph article entitled " So it appears that Arctic ice isn't vanishing after all" wrote:

"Yet [the NSIDC's] graph of northern hemisphere sea ice area, which shows the ice shrinking from 13,000 million sq km to just 4 million from the start of 2007 to October, also shows it now almost back to 13 million sq km."

As George Monbiot has pointed out:

"He even published a graph to demonstrate that the ice had indeed expanded between September and January. In other words, Booker appeared incapable of distinguishing between summer and winter."

During 2007, Arctic summer sea ice reached a record low extent, an anomalous event that resulted from specific weather conditions. Ice extents for years subsequent to 2007, whilst continuing to follow the overall trend of sea ice loss, have not reached the 2007 low, although 2011 came very close.

Booker has also misused this 2007 anomaly, comparing ice extents for later years to 2007 and declaring that sea ice is recovering. This is a prime example of 'cherry picking' data, as it completely ignores the long term trend of sea ice decline.

For example in a September 2009 Telegraph article Booker labelled a description of polar ice loss as "propaganda of the silliest kind", based on his argument that:

"...The extent of the ice now is 500,000 sq km (190,000 sq m) greater than it was this time last year - which was, in turn, 500,000 sq km more than in September 2007, the lowest point recently recorded."

David Rose of the Daily Mail - apparently another eager climate skeptic - wrote in a 2010 Daily Mail article:

"According to the US National Snow and Ice Data Centre in Colorado, Arctic summer sea ice has increased by 409,000 square miles, or 26 per cent, since 2007 - and even the most committed global warming activists do not dispute this."

Also David Whitehouse, of the Global Warming Policy Foundation (GWPF), was quoted in a 2010 Telegraph article:

"...It does seem that the sea ice is returning to 'average' after the record lows of 2007 and 2008. There has been a definite recovery trend since then so far from being a progression towards ice free summers it seems that it was a temporary dip.

"The recent observations do make the 2007 projections that the region would be ice free by 2013 look very unrealistic. Given what is happening only the foolish would look many years into the future and predict ice free summers now."

Of course, that there's more ice in winter doesn't equal a recovery from an overall decline in Arctic sea ice. Similarly, a particularly high or low sea ice extent doesn't tell us much.

Only by looking at long-term trends in Arctic sea ice extent, volume, thickness and age can we build up a detailed picture of what is really happening in the Arctic.

This hasn't stopped the likes of Booker and Rose in the past, however, and it seems too much to hope that they might take note in the future.

So, considering the temptation of a relatively fast October freeze-up, how long until the skeptics give in to temptation and say, "Arctic sea ice is recovering"?