In late 2009 the UK Meteorological office solemnly warned the world that it expected 2010 to be warmer than 1998, the hottest on the instrument record. (“Climate could warm to record levels in 2010”, Met Office, December 10, 2009)
A bastion of global warming theory, the Met Office went on to say that a record warm year is “not a certainty”, as the el Niño cycle then developing in the Pacific may give out early, and was referring to 2010 as a whole rather than the first few days of the year in the UK. But the release’s timing was most unfortunate as it had barely been issued before Britain was literally buried in snow, and exceptionally cold conditions had grounded airline traffic and stopped public transportation systems.
This proved too much even for the BBC which has faithfully reported the greenhouse line. In an interview gleefully shared around the growing network of sceptic newsletters and blogs Met office head, John Hirst, was grilled by a BBC presenter over these forecasts (broadcast January 7, 2010). The interview shed little light on the issue but it is by no means the first time the Met Office has issued a doubtful seasonal forecast. The UK’s The Independent newspaper estimates that the Met has failed to predict wet summers for the past three years; and that its annual global forecast predictions have been wrong for nine of the last 10 years (“Met office deserves to be shown the door”, The Independent, January 19, 2010). In 2009, for example, the office forecast a “barbecue summer”, only for the actual summer to be cooler and much wetter than previous summers.
The Met Office is hardly alone in making poor seasonal forecasts, incidentally. In 2007 the New Zealand Climate Science Coalition, which is definitely not pro-warming, issued an analysis of seasonal climate predictions by the country’s National Institute of Water and Atmospheric Research, which found that the overall accuracy of the predictions is just 48 per cent. (“World climate predictors right only half the time”, June 8, 2007). There is no reason to think anyone has a better success rate.
Despite the dismal track record of seasonal forecasting in general, and the disastrous PR results of “the hottest year” forecast in particular, that forecast has refused to die. The Met Office repeated it in May, as did NASA, and their warmings were duly echoed in the media. But both bodies should have been more cautious, for it is now apparent that a la Niña is on the way and that temperatures are falling as a result.
To explain, the Met Office’s initial warming was issued after it became apparent that an el Niño effect had emerged in the Pacific Ocean. We will not discuss what constitutes an el Niño or its reverse, a la Niña, except to note that they are both ocean-atmosphere cycles characterised by changes in sea surface temperatures in the Pacific. An el Niño is associated with warmer temperatures, a la Niña with colder, with each cycle likely to last anywhere between six to 18 months. At present there is no way to forecast when they will emerge or how long they will last, but scientists can tell when one is emerging by watching sea surface temperatures. (More information on the el Niño - la Niña cycle, collectively known as the El Niño Southern Oscillation or ENSO, is on the Bureau of Meteorology site.)
An el Niño effect pushed temperatures up to record highs in 1998 as shown on the satellite atmospheric temperature data compiled by University of Alabama in Huntsville. As so many questions have been raised about the reliability of the more widely used surface temperature data compiled by the Hadley Centre in the UK in recent months - the so called climategate incident was just one of the most public of these - the satellite data will be used for this article.
Global temperatures of the lower troposphere (the atmosphere) compiled by the University of Alabama in Huntsville. These have been projected to mid-2012 by simply taking temperatures from the last la Niña in 2008-09, and tacking them on the end of actual data to July 2010.
It is not intended as a serious forecast but as a benchmark.
In July, the Australian Bureau of Meteorology announced that a la Niña event was developing (Pacific Ocean in early stages of a La Niña event, BoM, Wednesday, July 21, 2010). Regular BoM updates available on the bureau web site show that as of August 18 the effect was still on track. The break in temperatures can also be seen on the satellite data, to July.
How long will the effect last? It is impossible to say, BoM only says it will last until at least the end of the year, and projects sea surface temperatures out for a few months beyond that. However, the previous el Niño effect was a very strong one that kept temperatures down for nearly two years, perhaps due to a different and much longer oceanic cycle called the Pacific Decadal Oscillation. Again we will not discuss the PDO and its two states the “warm mode” and the “cool mode” except to note that it is now in its cool mode, and while in its cool mode it amplifies the la Niña effect and damps down any el Niño effect. NASA joined those who recognised this effect in 2008 (“Larger Pacific climate event helps la Niña linger”, NAS-JPL, 21 April 2008). The PDO is now known to switch between states every 20 to 30 years and in 1998 was in its warm mode, so the el Niño effect of that year was amplified.
This is all explained in greater detail in my book, but the astonishing aspect of this is that the UK Met Office and NASA climate scientists should have been aware of this interaction between the two Pacific climate cycles, which now seems to be widely accepted, and should have been much more cautious in their forecasting. However, this attempt at seasonal or short term forecasting has grabbed a few headlines and the vast majority of the public would only have seen the headlines, and none of the backtracking. They will believe that this year is “the hottest year” for a long time to come.
As the UK Met Office proving so consistantly and disasterously wrong I have done my little bit to correct that impression with a basic attempt at forecasting. I have taken the temperature track from the last el Niño in 2008 and tacked it on to the end of actual temperatures to cover the next 18 months or so. This is not intended as a serious forecast but as a benchmark. Let us see how actual temperatures fare against my benchmark.
Whatever you want to make of that exercise the earth is not going to reach any tipping points for at least another year. Climate apocalypse has been postoned.
Mark Lawson is a senior journalist at the Australian Financial Review and a science writer. His book, A Guide to Climate Change Lunacy - bad forecasting, terrible solutions (Connor Court, RRP: $A29.90), is due in the bookshops on July 12, 2010.