do the benefits of global warming outweigh the costs?

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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, for possibly the first time in history, an entire article in the national press 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 2.2˚C of warming from 2009 (when he wrote his paper). This means approximately 3˚C from pre-industrial levels, since about 0.8˚C 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 consensis, 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, published as a chapter in a new book, called How Much have Global Problems Cost the World?, which is edited by Bjorn Lomborg, director of the Copenhagen Consensus Centre, and was reviewed by a group of leading economists. In this paper he casts his gaze backwards to the last century. He concludes that climate change did indeed raise human and planetary welfare during the 20th century.

You can choose not to believe the studies Prof Tol has collated. Or you can say the net benefit is small (which it is), you can argue that the benefits have accrued more to rich countries than poor countries (which is true) or you can emphasise that after 2080 climate change would probably do net harm to the world (which may also be true). You can even say you do not trust the models involved (though they have proved more reliable than the temperature models). But what you cannot do is deny that this is the current consensus. If you wish to accept the consensus on temperature models, then you should accept the consensus on economic benefit.

Overall, Prof Tol finds that climate change in the past century improved human welfare. By how much? 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. Note that if the world continues to grow at 3 per cent a year, then the average person will be about nine times as rich in 2080 as she is today. So low-lying Bangladesh will be able to afford the same kind of flood defences that the Dutch have today.

The chief benefits of global warming include: fewer winter deaths; lower energy costs; better agricultural yields; probably fewer droughts; maybe richer biodiversity. It is a little-known fact that winter deaths exceed summer deaths — not just in countries like Britain but also those with very warm summers, including Greece. Both Britain and Greece see mortality rates rise by 18 per cent each winter. Especially cold winters cause a rise in heart failures far greater than the rise in deaths during heatwaves.

Cold, not the heat, is the biggest killer. For the last decade, Brits have been dying from the cold at the average rate of 29,000 excess deaths each winter. Compare this to the heatwave ten years ago, which claimed 15,000 lives in France and just 2,000 in Britain. In the ten years since, there has been no summer death spike at all. Excess winter deaths hit the poor harder than the rich for the obvious reason: they cannot afford heating. And it is not just those at risk who benefit from moderate warming. Global warming has so far cut heating bills more than it has raised cooling bills. If it resumes after its current 17-year hiatus, and if the energy efficiency of our homes improves, then at some point the cost of cooling probably will exceed the cost of heating — probably from about 2035, Prof Tol estimates.

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, has had a measurable impact on plant growth rates. It is responsible for a startling change in the amount of greenery on the planet. As Dr Ranga Myneni of Boston University has documented, using three decades of satellite data, 31 per cent of the global vegetated area of the planet has become greener and just 3 per cent has become less green. This translates into a 14 per cent increase in productivity of ecosystems and has been observed in all vegetation types.

Dr Randall Donohue and colleagues of the CSIRO Land and Water department in Australia also analysed satellite data and found greening to be clearly attributable in part to the carbon dioxide fertilisation effect. Greening is especially pronounced in dry areas like the Sahel region of Africa, where satellites show a big increase in green vegetation since the 1970s.

It is often argued that global warming will hurt the world’s poorest hardest. What is seldom heard is that the decline of famines in the Sahel in recent years is partly due to more rainfall caused by moderate warming and partly due to more carbon dioxide itself: more greenery for goats to eat means more greenery left over for gazelles, so entire ecosystems have benefited.

Even polar bears are thriving so far, though this is mainly because of the cessation of hunting. None the less, 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. That’s the thing about climate change — we will probably pocket the benefits and mitigate at least some of the harm by adapting. For example, experts now agree that malaria will continue its rapid worldwide decline whatever the climate does.

Yet cherry-picking the bad news remains rife. A remarkable example of this was the IPCC’s last report in 2007, which said that global warming would cause ‘hundreds of millions of people [to be] exposed to increased water stress’ under four different scenarios of future warming. It cited a study, which had also counted numbers of people at reduced risk of water stress — and in each case that number was higher. The IPCC simply omitted the positive numbers.

Why does this matter? Even if climate change does produce slightly more welfare for the next 70 years, why take the risk that it will do great harm thereafter? There is one obvious reason: climate policy is already doing harm. Building wind turbines, growing biofuels and substituting wood for coal in power stations — all policies designed explicitly to fight climate change — have had negligible effects on carbon dioxide emissions. But they have driven people into fuel poverty, made industries uncompetitive, driven up food prices, accelerated the destruction of forests, killed rare birds of prey, and divided communities. To name just some of the effects. Mr Goklany estimates that globally nearly 200,000 people are dying every year, because we are turning 5 per cent of the world’s grain crop into motor fuel instead of food: that pushes people into malnutrition and death. In this country, 65 people a day are dying because they cannot afford to heat their homes properly, according to Christine Liddell of the University of Ulster, yet the government is planning to double the cost of electricity to consumers by 2030.

As Bjorn Lomborg has pointed out, the European Union will pay £165 billion for its current climate policies each and every year for the next 87 years. Britain’s climate policies — subsidising windmills, wood-burners, anaerobic digesters, electric vehicles and all the rest — is due to cost us £1.8 trillion over the course of this century. In exchange for that Brobdingnagian sum, we hope to lower the air temperature by about 0.005˚C — which will be undetectable by normal thermometers. The accepted consensus among economists is that every £100 spent fighting climate change brings £3 of benefit.

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.

Disclosure: by virtue of owning shares and land, I have some degree of interests in all almost all forms of energy generation: coal, wood, oil and gas, wind (reluctantly), nuclear, even biofuels, demand for which drives up wheat prices. I could probably make more money out of enthusiastically endorsing green energy than opposing it. So the argument presented here is not special pleading, just honest curiosity.