CLIMATE change has done more good than harm so far and is likely to continue doing so for most of this century. This is not some barmy, right-wing fantasy; it is the consensus of expert opinion. Yet almost nobody seems to know this.

Whenever I make the point in public, I am told by those who are paid to insult anybody who departs from climate alarm that I have got it embarrassingly wrong, don't know what I am talking about, must be referring to Britain only, rather than the world as a whole, and so forth.

At first, I thought this was just their usual bluster. But then I realised that they are genuinely unaware. Good news is no news, which is why the mainstream media largely ignores all studies showing net benefits of climate change. And academics have not exactly been keen to push such analysis forward. So here follows an article on the net benefits of climate change.

There are many likely effects of climate change: positive and negative, economic and ecological, humanitarian and financial. And if you aggregate them all, the overall effect is positive today - and likely to stay positive until around 2080. That was the conclusion of Professor Richard Tol of Sussex University after he reviewed 14 different studies of the effects of future climate trends.

To be precise, Prof Tol calculated that climate change would be beneficial up to 2.2C of warming from 2009. This means approximately 3C from pre-industrial levels, since about 0.8C of warming has happened in the last 150 years. The latest estimates of climate sensitivity suggest that such temperatures may not be reached till the end of the century - if at all. The Intergovernmental Panel on Climate Change, whose reports define the consensus, is sticking to older assumptions, however, which would mean net benefits till about 2080. Either way, it's a long way off.

Now Prof Tol has a new paper reviewed by a group of leading economists. In it he concludes that climate change in the past century improved human welfare. He calculates by 1.4 per cent of global economic output, rising to 1.5 per cent by 2025. For some people, this means the difference between survival and starvation.

It will still be 1.2 per cent around 2050 and will not turn negative until around 2080. In short, my children will be very old before global warming stops benefiting the world.

The chief benefits of global warming include: fewer winter deaths; lower energy costs; better agricultural yields; probably fewer droughts; maybe richer biodiversity.

The greatest benefit from climate change comes not from temperature change but from carbon dioxide itself. It is not pollution, but the raw material from which plants make carbohydrates and thence proteins and fats. As it is an extremely rare trace gas in the air - less than 0.04 per cent of the air on average - plants struggle to absorb enough of it. On a windless, sunny day, a field of corn can suck half the carbon dioxide out of the air. Commercial greenhouse operators therefore pump carbon dioxide into their greenhouses to raise plant growth rates.

The increase in average carbon dioxide levels over the past century, from 0.03 per cent to 0.04 per cent of the air is responsible for a startling change in the amount of greenery on the planet. As Dr ­Ranga Myneni of Boston University has documented, 31 per cent of the global vegetated area of the planet has become greener and just 3 per cent has become less green.

Dr Randall Donohue and colleagues of the CSIRO Land and Water department also analysed satellite data and found greening to be clearly attributable in part to the carbon dioxide fertilisation effect.

Even polar bears are thriving so far, though this is mainly because of the cessation of hunting. Nonetheless, it's worth noting that the three years with the lowest polar bear cub survival in the western Hudson Bay (1974, 1984 and 1992) were the years when the sea ice was too thick for ringed seals to appear in good numbers in spring. Bears need broken ice.

Well yes, you may argue, but what about all the weather disasters caused by climate change? Entirely mythical - so far. The latest IPCC report is admirably frank about this, reporting "no significant observed trends in global tropical cyclone frequency over the past century … lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency offloads on a global scale … low confidence in observed trends in small-scale severe weather phenomena such as hail and thunderstorms".

In fact, the death rate from droughts, floods and storms has dropped by 98 per cent since the 1920s, according to a careful study by the independent scholar Indur Goklany. Not because weather has become less dangerous but because people have gained better protection as they got richer: witness the remarkable success of cyclone warnings in India last week.

So we are doing real harm now to impede a change that will produce net benefits for 70 years. That's like having radiotherapy because you are feeling too well. I just don't share the certainty of so many in the green establishment that it's worth it.

It may be, but it may not.

Matt Ridley is a British scientist and journalist. This is an edited version of an article which first appeared in the Spectator Australia.

Originally published as Give thanks to global warming