Jan 042008

A Happy New Year to everyone.

The BBC’s Today progamme celebrated New Year’s Day, in spite of a little confusion about what year we are in, by introducing a news item with the following words:

Now this year [2007] is likely to be the second warmest for England and Wales on record. Figures released by the Met Office show that average temperatures reached 9.6° C, that’s just over 49° F, and overall the last six years have been the warmest since records began in 1914.

Listen Again: item at 08.39

As someone who has become sceptical about pronouncements that add to public concern over warming, this lead-in to what promised to be a thoroughly depressing prelude to the New Year presented a happy hunting ground in which to pose awkward questions.

To help ram the story home with some seasonal doom and gloom, the editors had enlisted the enthusiastic help of Philip Eden, a meteorologist, weather journalist and vice-president of the Royal Meteorological Society who has also published an excellent book on the vagaries of the British climate: Change in the Weather.

Presenter (following on from the quotation above): Is this part of an underlying trend?

Philip Eden: I think it is, yes. We can do even better than these statistics, actually, because we do have temperature records for central England which stretch back over three centuries, and in that very, very long record, one of the longest records in the world, the last few years have all been in the top half dozen, and of course the weather doesn’t actually stick to the calendar year, and we can identify the warmest period in the last couple of years, the warmest twelve month period ran from June 2006 to May 2007. And that twelve-month period was, by quite a long margin, quite a wide margin, the warmest twelve month period of any.

So here are a few questions:
Why are we told that temperature records began in 1914, when instrumental records are available as far back as the mid 1800s?
Why is the Met Office only citing data for England and Wales rather than UK or global data?
Why are the last six years the warmest ‘overall’, and not just the warmest?
Why should a eminent meteorologist want to ‘do better than those statistics’?

The Met Office has become rather capricious in its selection of reference dates for records lately. For instance on 3rd July 2007 they put out a press release about rainfall during June 2007 saying:

Provisional statistics from the Met Office have today shown that June has been the wettest since records began in 1914. (Here)

Needless to say, most journalists wrote this up as either ‘Wettest June since records began’ or even ‘Wettest June ever!’ But according to Philip Eden, writing in the Sunday Telegraph on 1st of July 2007:

Averaged nationally, last month failed to break the “wettest June” record by some margin ….. there have been seven wetter Junes in the last 240 years. [See Met Office dataset that confirms this here]

Unfortunately, for all their claimed skill in weather and climate prediction, the Met Office had not anticipated what would happen in July. This must have lead to some head scratching in the publicity department before they came up with the following pronouncement in a press release issued on 26th July 2007:

The Met Office today can reveal the three months from May to July 2007 have broken records for this period, even before July is over.

Provisional figures from the Met Office show that 387.6 mm of rain have already fallen across England and Wales, making it the wettest May to July since the England and Wales Precipitation record began in 1766. (Here)

So when did rainfall records begin? At the Met Office, an institution that could once be relied on to provide the most accurate data available on our very unpredictable weather, the answer would seem to be; ‘That depends on the impact that can be achieved in a press release’. Does this also apply to the information supplied to the BBC about the 2007 temperatures in England and Wales since 1914, but not including Scotland and Northern Ireland, which have stubbornly refused to show the same alarming trends as their neighbours?

No doubt the reference to the ‘overall’ warmth, rather than just warmth, of the last six years has some sound basis in Met Office’s statistical analyses, but without being able to see the original press release it’s rather difficult to see why this qualification is necessary. A glance at a graph on the Met Office’s website tells a rather different story.

HadCRUT3 Global Temps since 1850

http://www.metoffice.gov.uk/research/hadleycentre/obsdata/HadCRUT3.html

Of course this shows global temperatures, not just those for England and Wales, which is what the BBC seem to be referring to. But the downward tick at the right hand end of the graph is quite unambiguous. It shows that there is a now a clear downward trend in temperatures that started about six years ago. Are the Met Office, via the information they supplied to the BBC, implying that the data for England and Wales is a more reliable indicator of temperature trends than the global data on their own website? It seems very unlikely that they would do so. Yet when a BBC presenter announces that, according to the Met Office, 2007 is the second warmest on record in England and Wales, and then adds in the same breath that the six most recent years are also ‘overall’ the warmest on record, the listener is likely to get the impression that this is some new and terrible revelation about rising temperatures that has come from an impeccable scientific source.

If we look at the Central England Temperature series, which Philip Eden cited in his interview, then this tells a rather interesting story too. A table on the Met Office website (Here) gives a breakdown of mean temperatures by rank: coolest first, warmest last. Looking at the bottom right hand corner we see that the six warmest years are; 2006, 1999, 1990, 1949, 2002, 1997. Only two of these fall within the last six years. Moving a little further up the column we find that 2007 is in fact 12th equal with 2004 and 1959, not nearly such an exciting result as second place in the England and Wales temperature stakes.

It is also surprising that Philip Eden should choose data from the Central England Temperature series to suggest that the twelve months from June 2006 to May 2007 were the warmest in 350 years, but ignore the fact that this series puts a very different slant on the Met Office claim about 2007 being the second warmest on record and the last six warmest years also being the warmest.

Climate science is not, so far as I know, supposed to be a competitive sport. It is very important, particularly at the moment, that we should be able to rely on authorities such as Mr Eden and the Met Office for cautious, objective, science-based opinions that are intended to inform, and not guide, public opinion. Doom laden headlines like the introduction to this news item on Today should not inspire the only expert who they chose to interviewed to say, ‘we can do even better than these statistics’, before delivering even more scary evidence of impending catastrophe that are derived from some rather neat cherry-picking of the most sensational data.

Just one more thing. A Met Office Press release dated 13th December 2007 says:

The provisional global figure, using data from January to November, currently places 2007 as the seventh warmest on record since 1850. (Here)

Apparently temperature records can start in 1850 when it sexes up a story.

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