Friday, January 28, 2005

Global warning

'Alarm at new climate warning', says BBC News, reporting on a new study by researchers at Oxford University's Department of Physics. Simulations of climate change were run using a screensaver programme by over 90,000 participants around the world, looking at a variety of combinations of different climate parameters. The results indicate that a much wider range of outcomes is possible, with global mean temperatures rising by up to 11 degrees Celsius. Project leader David Stainforth told BBC News: 'I think these results suggest that our need to do something about climate change is perhaps even more urgent.'

No new measurements have been taken in the real world - instead, these results are derived from models making a whole series of assumptions. Unsurprisingly, with many different variables being altered, the range of possible outcomes is very wide, with some scenarios producing a temperature rise of only two degrees Celsius.

As spiked contributor John Brignell has pointed out: 'computer models are dangerous tools' unless the assumptions they make are valid, clear to all, and can be tested against real-world experience. However, proper understanding of the physical processes involved in climate, and the very complex interactions between different elements, is simply not good enough to be able to produce accurate models.

For example, the most important greenhouse factors are water vapour and clouds. Any temperature rise due to carbon dioxide alone will be quite small. It is positive feedback effects on water vapour and clouds that produce the big temperature increases widely discussed. But we do not know if such positive feedbacks will happen, let alone to what degree.

We can be reasonably certain that there has been an increase in global temperature over the past 100 years. But the rise - 0.6 degrees Celsius - is small. Whether this really is unusual, and whether it is caused by carbon emissions or is due to natural variability beyond our control, is disputed. This latest study doesn't answer these questions.

What is absolutely certain is that climate has always changed, and that humans already live in a wide range of different conditions. The real problem with the climate change alarmists is their unwillingness to believe that human society can adapt. Why bother producing these complex models if the most important assumption is that we're doomed before we start?

Alarm at new climate warning, BBC News, 26 January 2005

Computer modelling, Numberwatch