Global warming stopped six years ago. It might start again tomorrow, but from 2002 until now, average global temperatures have remained fairly constant. This is in contrast to the previous period when, as everyone knows, the temperature trend was upwards.

Most people I've mentioned this to were not aware of it. They assumed that temperatures had continued to rise in line with greenhouse gas emissions, which have certainly continued to increase. So it's worth looking at what's happened.

The two most prominent organisations that record global average temperatures are the British Met Office's Hadley Centre and America's National Climatic Data Centre. Their records might be called "official"- Hadley, for instance, is closely involved with the Intergovernmental Panel on Climate Change. Their records for temperature change can be found at their websites.

Hadley expresses temperature changes in terms of deviations from the 1961 to 1990 average. In 2002 the rounded global temperature for land and sea was 0.46 above that average. In the next five years it was: 0.46, 0.43, 0.48, 0.42, and 0.40. The figures for the date centre are calculated slightly differently, but they too show no trend over the period in question.

What does this mean? Some global warming sceptics say these figures disprove the basic hypothesis of global warming, that rising greenhouse gas emissions automatically produce rising temperatures. Some have looked back to 1998, an unusually hot year (0.52 on Hadley's list) and said that global warming actually stopped back then. They conclude that after 10 years we can now say global warming is over, and we face the possibility of global cooling.

I suspect it's still too early to make these conclusions. As a sceptic on this issue, I've spent years arguing that we just don't know enough about what's going on to predict the future with any certainty. It's too soon to junk that caution based on six (or even 10) years' data and claim that global warming is over. The earth might start to cool next year (not necessarily a pleasant thought, incidentally), it might stay the same, or it might start to warm again. I don't think any of us knows.

This is the argument that has been put by some on the other side of the issue. Some have also suggested that the warming trend has actually continued, despite the above figures. A good source for this position is the paper Waiting For Global Cooling, published last month by Robert Fawcett and David Jones of the National Climate Centre at the Australian Bureau of Meteorology. They say that the El Nino effect boosted the temperature for 1998, while the recent La Nina suppressed it, thereby masking the underlying trend. According to them, "the linear trend in globally-averaged annual mean temperatures … over the period 1998-2007 remains upward".

This conclusion depends on the way they have used the raw data to calculate their trend line. As so often in the global warming debate, much depends on which data you look at and what you do with it.

Whatever the recent figures might signify, it's disturbing that they haven't received more publicity. If the trend had been different - if warming had accelerated, say - you can bet it would have been reported everywhere.

But because the figures since 2002 might raise doubts about the orthodoxy, there has been a great silence. Most of those involved in public discussion of global warming simply ignored what was happening to the temperature record. The media have continued to interpret any minor weather event as proof of global warming. Political leaders have continued to crank up the panic.

It's a response that has to raise concerns about the relative roles of reason, emotion and propaganda in public consideration of global warming.

The implications of the past six years for public policy are the same as for science: we need to be cautious. We simply don't know enough about this matter to justify urgent and dramatic action. It's worth reflecting on the number of scientists who are certain about what the temperature trend will be in a 100 years, yet in 2001 were unable to predict what would happen in the next six.

It's hard for a lay person to keep abreast of even the most important developments in the science of climate change. To help, a website was launched this year that I strongly recommend. It's called climatedebatedaily.com, and presents the latest important news about climate change in two columns, one for those who accept the global warming orthodoxy and one for the sceptics. It's a clever idea, because the format encourages users with strong views to dip into the arguments on the other side.

The site was begun by Denis Dutton, creator of Arts and Letters Daily (aldaily.com), the very popular site for those interested in the humanities and the arts, and Douglas Campbell. Both are academics at the University of Canterbury in New Zealand. It is funded by Peter Farrell, executive chairman of ResMed, the Australian company that makes products to treat sleep disorders.

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