Matt Ridley: A Lukewarmer’s Ten Tests

I have written about climate change and energy policy for more than 25 years. I have come to the conclusion that current energy and climate policy is probably more dangerous, both economically and ecologically, than climate change itself. This is not the same as arguing that climate has not changed or that mankind is not partly responsible. That the climate has changed because of man-made carbon dioxide I fully accept. What I do not accept is that the change is or will be damaging, or that current policy would prevent it.

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For the benefit of supporters of climate change policy who feel frustrated by the reluctance of people like me to accept their assurances, here is what they would need to do to change my mind.

1. I need persuading that the urban heat island effect has been fully purged from the surface temperature record. Satellites are showing less warming than the surface thermometers, and there is evidence that local warming of growing cities, and poor siting of thermometers, is still contaminating the global record. I also need to be convinced that the adjustments made by those who compile the global temperature records are justified. Since 2008 alone, NASA has added about 0.1C of warming to the trend by unexplained “adjustments” to old records. It is not reassuring that one of the main surface temperature records is produced by an extremist prepared to get himself arrested (James Hansen).
2. Despite these two contaminating factors, the temperature trend remains modest: not much more than 0.1 C per decade since 1979. So I would need persuading that water vapour will amplify CO2’s effect threefold in the future but has not done so yet. This is what the models assume despite evidence that clouds formed from water vapour are more likely to moderate than amplify any warming.
3. Nor am I convinced that sulphate aerosols and ocean heat uptake can explain the gap between model predictions and actual observations over the last 34 years. Both are now well understood and provide insufficient excuse for such an underperformance. Negative cloud feedback, leading to total feedbacks being modest, is the more plausible explanation.
4. The one trend that has been worse than expected – Arctic sea ice – is plausibly explained by black carbon (soot), not carbon dioxide. Soot from dirty diesel engines and coal-fired power stations is now reckoned to be a far greater factor in climate change than before; it is a short-lived pollutant, easily dealt with by local rather than global action. So you would need to persuade me that this finding, by explaining some recent climate change, does not further reduce the likely sensitivity of the atmosphere to carbon dioxide. Certainly, it “buys time”.
5. Even the Met Office admits that the failure of the models to predict the temperature standstill of the last 16 years is evidence that natural factors can match man-made ones. We now know there is nothing unprecedented about the level and rate of change of temperature today compared with Medieval, Roman, Holocene Optimum and other post-glacial periods, when carbon dioxide levels did not change significantly, but temperatures did. I would need persuading that natural factors cannot continue to match man-made ones.
6. Given that we know that the warming so far has increased global vegetation cover, increased precipitation, lengthened growing seasons, cause minimal ecological change and had no impact on extreme weather events, I need persuading that future warming will be fast enough and large enough to do net harm rather than net good. Unless water-vapour-supercharged, the models suggest a high probability of temperatures changing less than 2C, which almost everybody agrees will do net good.
7. Nor is it clear that ecosystems and people will fail to adapt, for there is clear evidence that adaptation has already vastly reduced damage from the existing climate – there has been a 98% reduction in the probability of death from drought, flood or storm since the 1920s, for example, and malaria retreated rapidly even as the temperature rose during the twentieth century.

Full paper with graphs and references here Dr Matt Ridley Matt Ridley has been a scientist, journalist and businessman. With BA and DPhil degrees from Oxford University, he worked for the Economist for nine years as science editor, Washington correspondent and American editor, before becoming a self-employed writer and businessman. He is the author of several books, which have sold over 900,000 copies, been translated into 30 languages, been short-listed for nine major literary prizes and won several awards. He is a member of the GWPF’s Academic Advisory Council.

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