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More Met Office Spin About Annual Temperatures (In Time for Durban)

Dr David Whitehouse

Once again, for political reasons, the Met Office is “jumping the gun” and drawing conclusions about the global annual temperature of 2011 before all the data has come in. It is also erroneously saying that even with a globally cooling La Nina event 2011 is a record year.

Reported in the Times today (paywall) and in the Guardian are a series of statements prepared by the UK Met Office that are a masterclass of spin in the use of statistics. The Met Office Press release is here.

The Times: World temperatures still rising (as spring daffodils flower in November). Hannah Devlin, Science Correspondent
Temperatures across the world are continuing to rise as predicted by climate change scientists, according to the latest global figures released by the Met Office.
The figures, timed to coincide with the UN climate conference in South Africa, show that this year is likely to be the eleventh warmest on record. The average global temperature for the first ten months of 2011 was 14.36C (57.85F), 0.36C above the long-term average.
Although cooler than last year, scientists said this is explained by a weather phenomenon called La Niña, which causes a temporary cooling of the global climate.
When 2011 is compared with previous La Niña years, it ranks as the warmest since records began in 1850. Peter Stott, from the Met Office, said: “This year we have seen a very persistent and strong La Niña, which brings cooler water to the surface of the Pacific Ocean. This has a global impact on weather and temperatures, and is one of the key reasons why this year does not figure as highly as 2010 in the rankings.”
He added that the Met Office stood by a previous prediction that half the years in this decade would be warmer globally than 1998, the warmest year to date. 
Phil Jones, director of the Climatic Research Unit at the University of East Anglia, which worked with the Met Office on the figures, said that the records provided “overwhelming” evidence that the climate has warmed, but that  not every year would be warmer than the last.

There is a great deal of misrepresentation in this article. Somehow its twisted logic concludes that even as 2011 turns out to be a rather cool year, as it admits probably the 11th warmest on record taking us back to the temperatures in the 1990’s before the recent warmest decade on record, somehow the world’s temperature continues to rise as expected.

I will pass judgement on 2011 when all the data is in, but if it is on a par with global temperatures seen in the 1990’s – when the decadal average was lower than the average of the past ten years – it certainly does not indicate that temperatures are continuing upward.

As for the statement, attributed to Prof Phil Jones that the records provide “overwhelming” evidence that the world has warmed, well yes. We all know that. That’s not news and is not proof of why it is warming, or more specifically the contribution made by mankind to it. It is an often used sleight of hand argument, dragooning an undisputed fact to support a point of view outside its remit.

But what of the statement by Peter Stott that the La Nina influenced 2011 is a record year.

There is only one other La Nina in the past decade, see here and here. It occurred between the middle of 2007 and the middle of 2008. The NOAA Climate Prediction Centre said that in June 2007 a transition from ENSO neutral conditions to La Nina conditions was likely within the next 1-3 months. By September lower sea surface temperatures signalled the start of a La Nina event. By April 2008 the La Nina had declined to moderate strength, and in May NOAA predicted that there would be a transition to ENSO neutral conditions soon. By July 2008 that transition had taken place.

The most recent La Nina began in mid-2010 and continued to the Spring of 2011. In May 2010 the prediction was for the transition from ENSO neutral in June. It took place in July/August. The La Nina persisted to January 2011 and began to decline in strength, already some regions were returning to average temperatures. Sea surface and sub-surface temperatures in the equatorial Pacific were steadily increasing and by May an ENSO neutral pattern had returned.

However, the La Nina returned during October 2011 and is now expected to persist into next year.

Looking at the HadCRUt3 global temperature dataset 2007 and 2008 are slightly cooler years (temp anomaly, 1961 – 1990 average, of 0.397 and 0.329 respectively.) Though bear in mind the errors in the measurements that make 2001 – 2010 statistically indistinguishable.

Looking at El Nino years (2002-2003, 2004-2005,2006-2007, 2009-2010) temperature anomalies tend to be higher, 0.455, 0.467, 0.444, 0.474, 0.425, 0.436, 0.470.

The temperature anomaly for 2011 (data until October) is 0.356. So far the evidence is that the temperature of 2011 has not been suppressed by a La Nina to a greater extent that, say, 2008, and given the errors in measurement, it seems to be identical to what happened in 2007 and 2008.

Political Lobbying

It’s difficult to say what the temperature of 2011 would have been had the La Nina not occurred, but there is no evidence it would not have been similar to the other years of the past decade with or without a El Nino. I conclude that there is no evidence to support the Met Office’s statement. The Met Office is spinning the data at the start of the UN climate talks in Durban. As it did for Copenhagen in 2009, “Climate could warm to record levels in 2010” and Cancun in 2010, “Near record temperatures in 2010.” See also, “2010 A near record year

In 2009 the GWPF criticised the Met Office for political lobbying. Things have not changed.

As for the statement that the Met Office expects that at least half the years of this decade to exceed the temperature anomaly of 1998 (0.529). Already 2011 does not exceed 1998, and if the current La Nina extends into the Spring of next year 2012 is unlikely to do so. So that means 6 of the following 8 years will have to exceed the temperature of 1998. This would mean a fundamental change of the nature of the data seen post 2008 requiring a highly significant increase in temperature in a few years. Such a change would be unambiguous, in its presence, or absence.

Also, in the absence of important UN climate meetings in December of the year I wonder if the Met Office would issue estimates for the global average temperature for the previous year based on only 10 months of data (83% of the annual data). It is a most illogical thing to do, especially as sometimes the data from the final two months can make a difference, often unacknowledged afterwards.

Finally, it is disappointing that the Science Correspondent of the Times and the Environment Correspondent of the Guardian has been so supine in letting such contentious statements pass unanalysed and uncommented upon.