The world climate conference that begins today in Kyoto, Japan, is being described as the last great environmental battle of the 20th century. When it comes to global warming, however, the difference between responsible behaviour and panic is too close to call.

At the end of last week, we were deluged with predictions of potential disaster. By 2050, drought will threaten the lives of 100 million more people; by 2080, floods will threaten another 200 million. Global warming, caused by all that carbon dioxide we're spewing out into the atmosphere, is melting ice-caps and heating up the world.

In another report on the same day, we read that for us in Britain, it could be the opposite. All that melted ice would create such currents of cold water that the gulf stream would change direction and we'd end up with a near Arctic climate.

And a third report tied it all up neatly: 1997 is heading for being the warmest year on record. That's proof that global warming is with us, and it's all our fault, and it's time we did something about it.

Now hang on a moment. Let's just think about that "warmest year on record". The records date back to about 1860, which was the end of the "Little Ice Age". Shouldn't we expect it to be getting gradually warmer?

The steepest rise of all was between 1910 and the early Forties, after which there was a gradual drop in temperature over the next 30 or so years, followed by the recent rise. It may well be that greenhouse gas emissions are pushing temperatures higher than they would otherwise have been, but it is also clear that other factors are having a greater effect.

The predictions currently being made of rising temperatures are based on extrapolating the trends of the past 100 years - yet might we not just as well extrapolate backwards and deduce complete nonsense about what the temperature of the earth must have been a few centuries ago? In any case, 100 years of data are hardly enough to trust an extrapolation another 100 years into the future.

Now, what about that frozen Britain hypothesis? It depends on a model of the behaviour of the oceans when vast amounts of cold waters are released into them. But we don't even understand how the oceans behave when they are left alone - as the mysterious El Nino keeps reminding us.

All the scepticism expressed above, of course, is grossly irresponsible. There is little doubt that burning fossil fuels in vast quantities is taking a risk with the environment. Perhaps it is a negligible risk; perhaps it is a huge risk. The disturbing aspect is that the debate seems to have been hijacked by political activists. It always seems to be spokespersons for Green pressure groups, or scientists from government-funded agencies, who tell us how bad the situation is.

Somewhere, there must be some truly independent scientists who are prepared to say exactly how much we know - and, perhaps more important, how much we don't know - about the process of global warming, yet we never seem to hear anything from them.

There may be something very important going on in our skies, but the Kyoto conference will do little to throw light on it. Instead, we shall have just another contribution to the ever-increasing amounts of global hot air. I wonder if they'll agree to cut emissions by as much as was created by the airline fuel needed to fly them all there.