Of course, you can hide a lot in an average. So it is interesting to see what exactly these figures are an average of. As reported (or should I say "admitted") by the BBC, the Met Office has published a study plotting the likely climate impacts on 24 countries around the world. They're not exactly convincing.
It seems that 21 different computer models of climate were used to assess various locations as to their vulnerability to floods, rainfall changes and suitability for growing crops. You would think that, if the "science is settled", then the answers would be fairly consistent. However, the proportion of UK farmland likely to become more fertile, is apparently somewhere between 60% and 99%. Aside from being good news rather than bad, that is quite a wide range indicating that the models underlying this prediction are exercises in guesswork at best. Worse still is the prediction of flooding risk, with estimates ranging from a 180% increase in flood risk to a 56% reduction.
Looking into other countries, where they do not have our history of meticulously recording the weather, it is even worse. Bangladesh's change in flood risk is somewhere between -59% (that's minus 59%) to +557%. Egypt could be anywhere between 100% better off, or 206% worse off.
When 21 "state-of-the-art" models reach such divergent conclusions, only one conclusion can be reached. They're all rubbish.
I'll leave the last word to the BBC:
As a policymaker, as a business leader, as a citizen, would you make decisions on the basis of these models?No. I wouldn't.
(Hat Tip to the Filthy Engineer, again...)