Matt Ridley: Earth To Met Office: Check Your Climate Facts

Matt Ridley: Earth To Met Office: Check Your Climate Facts
The Times, 20 May 2013

The latest science suggests that our policy on global warming is hopelessly misguided

There is little doubt that the damage being done by climate-change policies currently exceeds the damage being done by climate change, and will for several decades yet. Hunger, rainforest destruction, excess cold-weather deaths and reduced economic growth are all exacerbated by the rush to biomass and wind. These dwarf any possible effects of worse weather, for which there is still no actual evidence anyway: recent droughts, floods and storms are within historic variability.

The harm done by policy falls disproportionately on the poor. Climate worriers claim that at some point this will reverse and the disease will become worse than the cure. An acceleration in temperature rise, they say, is overdue. The snag is, the best science now says otherwise. Whereas the politicians, activists and businessmen who make the most noise about — and money from — this issue are sticking to their guns, key scientists are backing away from predictions of rapid warming.

Yesterday saw the publication of a paper in a prestigious journal,Nature Geoscience, from a high-profile international team led by Oxford scientists. The contributors include 14 lead authors of the forthcoming Intergovernmental Panel on Climate Change scientific report; two are lead authors of the crucial chapter 10: professors Myles Allen and Gabriele Hegerl.

So this study is about as authoritative as you can get. It uses the most robust method, of analysing the Earth’s heat budget over the past hundred years or so, to estimate a “transient climate response” — the amount of warming that, with rising emissions, the world is likely to experience by the time carbon dioxide levels have doubled since pre-industrial times.

The most likely estimate is 1.3C. Even if we reach doubled carbon dioxide in just 50 years, we can expect the world to be about two-thirds of a degree warmer than it is now, maybe a bit more if other greenhouse gases increase too. That is to say, up until my teenage children reach retirement age, they will have experienced further warming at about the same rate as I have experienced since I was at school.

At this rate, it will be the last decades of this century before global warming does net harm. As the economist Bjørn Lomborg recently summarised the economic consensus: “Economic models show that the overall impact of a moderate warming (1-2C) will be beneficial [so] global warming is a net benefit now and will likely stay so till about 2070.”

Now contrast the new result with the Met Office’s flagship climate model, the one that ministers and their advisers place most faith in. Called HadGEM2-ES, it expects a transient climate response of 2.5C, or almost double the best estimate that the Oxford team has just published. Indeed, the latter’s study concludes that it is more than 95 per cent certain that the response is below 2C, considerably short of the Met Office model’s estimate.

Why trust the new results rather than the Met Office model? The new study not only uses the most robust method, but joins several other observationally based studies from the past year that also find lower climate sensitivity than complex climate models exhibit.

Notice that this new understanding is consistent with what we have actually experienced: about 0.1C per decade over the past 50 years. The most remarkable thing about the recent milestone of 0.04 per cent carbon dioxide in the atmosphere (400 parts per million) is that it comes after 15 years of no net warming at all.

The new paper also fits the known physics of the greenhouse effect, which predicts a warming of 1.1C for a doubling of carbon dioxide. Only unverified assumptions by modellers about the added effects of water vapour and clouds have allowed politicians and activists to claim that a much higher number fits the laws of physics. Only now-disproven claims about how much the sulphur pollution in the air was masking the warming enabled them to reconcile their claims with the actual data.

It is true that the “transient climate response” is not the end of the story and that the gradual warming of the oceans means that there would be more warming in the pipeline even if we stopped increasing carbon dioxide levels after doubling them. But given the advance of nuclear and solar technology, there is now a good chance we will have decarbonised the economy before any net harm has been done.

In an insightful new book, The Age of Global Warming, Rupert Darwall makes the point that “in believing scientists and politicians can solve the problems of a far distant future, the tangible needs of the present are neglected”. The strong possibility that climate change will be slow and harmless must be taken seriously before we damage more lives, landscapes and livelihoods in its name.

Matt Ridley is the author of The Rational Optimist (HarperCollins) and a member of the GWPF’s Academic Advisory Council