If you want absolute certainty on the causes of climate change, you're going to be waiting for a very, very long time.

“The Climate Science Isn't Settled,” reads a December 1 headline in The Wall Street Journal. Has a journalist uncovered the greatest hoax on humanity ever? Is the unquestionable proof that skeptics demand before we act on climate change now discredited?

But how many people really know what it means to “prove” something? The concept is used in so many areas of our lives and sounds so simple. In courtrooms we see lawyers “prove” that crimes were committed. You probably remember “proving” a mathematical theorem in high school. Scientists may even talk of “proving” a scientific law.

While the concept of proof is used in many different areas, its meaning is often quite different. When we confuse these different definitions, the result can be dangerous. Climategate is playing on this confusion. The issue is not whether data was falsified. It wasn't. The issue is how the public perception of climate change and what must be done about it has changed – that what was once considered “proven” is no longer.

What are the different meanings of proof? Speaking as a scientist, evidence and proof in law seem particularly nebulous. We've all seen opening statements in TV courtroom dramas – a defence lawyer boldly proclaims he or she will prove their client's innocence. But what happened to reasonable doubt? On television it is frequently out-competed by certainty, no matter how unrealistic.

Doubt has too many shades of grey and too little drama. The widely discussed “CSI effect” – that jurors who have watched the TV show believe forensic evidence can even provide proof beyond reasonable doubt – has caused consternation in courtrooms across North America. Following the acquittal of the actor Robert Blake on murder charges, the news media was dominated by analysis of whether the jurors failed in their duty. The Wall Street Journal even quoted Los Angeles District Attorney Steve Cooley as calling the jurors "incredibly stupid" following the trial.

Was the forensic evidence so poor? Has the unquestionably compelling – but false – certainty of CSI made us less able to handle the uncertainty of reality?

If you want unquestionable proof, look to mathematics and logic – you won't find it anywhere else. At its very simplest level, mathematics builds on a system of rules, or axioms. (1+1=2 is an axiom.) We don't ask why it is true. It is a definition – something that is unquestionably, fundamentally true. Mathematical proofs use axioms to uncover absolutely certain results. It is a comforting thought that Euclid's proof of the Pythagorean Theorem will not suddenly become untrue because of some new evidence that 1+1 does not actually equal 2.

Science, however, is not mathematics. You cannot prove a scientific theory is absolutely, 100 per cent true. To many people outside science this comes as a surprise. Non-scientists are used to reading headlines about scientists proving the link between a cause and an effect. Yet just because you can see one factor repeatedly influence an event, that doesn't mean it caused it. Or as scientists like to say, correlation does not imply causation.

This is not as damning as it sounds. Science can prove whether theories are false. And that makes scientists the ultimate pragmatists. We work with theories that might be true, but we're never able to know for sure. It's all a question of statistics. Theories are accurate to a certain level of probability, or uncertainty. Knowing the uncertainty is what matters.

Scientists also carry some of the blame for the confusion around proof. Extremely accurate theories that have not yet been proven wrong are often promoted to the hallowed status of a “Law.” Yet some laws are eventually shown to be wrong. Newton's Law of Universal Gravitation is an example. Thanks to Einstein, we now have an even more accurate theory of gravity, General Relativity.

Thus, the “beyond a reasonable doubt” clause of law parallels doubt in science. Proof is not absolute in science, and climate science is no exception to this rule. That's why the IPCC reports talk of man being the cause of climate change at 90 to 95 per cent probability. It isn't because the scientists “haven't figured it out yet.” Doubt and uncertainty, the shades of grey that ruin a good media story, are the currency of scientific progress.

Over the coming decades, climate scientists will debate the precise details of their models. Uncertainties will be reduced, but absolute certainty will never be found. So if you think there needs to be certainty on climate change, you've come up with a recipe for doing nothing. The science will never be 100 per cent settled. But how many of you would bet on man not being the cause at 1 in 10, or 1 in 20 odds? Climategate doesn't change these numbers either. Since no data was falsified, clearly no proof has been lost.

I can't help but wonder whether we would see more enlightened policy debates if the subtleties of proof were better understood. Would the jurors in trials across North America come to different decisions? Would the questions of climate change and ultimately the future of mankind be better framed? I think so. But of course, I can't prove it.