Scientists can't say for sure that humans are the cause of global climate change. They're still a little uncertain, and that's a good thing. It means the science is working the way it should.

A well-educated friend of mine, a climate-change skeptic, once told me that he didn't believe anything coming out of the big computer models that scientists use to reason about the complex nonlinear feedbacks driving the Earth's climate system. He has a point: Researchers are doing the best they can in the midst of great complication and uncertainty.

My surprise came a few minutes later, when my friend announced that it is, in any event, obvious that recent global warming couldn't possibly be caused by humans. Somehow, the forbidding complexity of climate physics didn't prevent his intuition from finding its way to rock-solid conclusions, without the aid of any models at all.

I recalled my friend's odd logic amid the reaction to the most recent report from the Intergovernmental Panel on Climate Change. The report -- its contents were leaked in June, and it will be officially released this week --concludes that it's now 95 percent certain that human activity lies behind at least half the warming seen in the past half-century. Skeptics savaged the report for revising slightly downward earlier estimates of the warming likely to be seen in the next two decades -- as if trying to be accurate was an offense.

David Fuller's view Climate uncertainty is an understandably emotive topic which Fullermoney has not shied away from, because it could be anything from a minor and largely natural change in global weather patterns to the global catastrophe predicted by some environmentalists.

The only certainty is that no one knows what the future holds. However, it would not be unreasonable to assume that humans are a factor in potential climate change. Therefore we should use our technologies to reduce any human influence on our climate, especially as this can be done without crippling our economies.