A KEY number in the struggle to tackle global warming is flawed. The cost of adapting to the effects of climate change is two to three times the figure quoted by the UN climate change convention, a new study claims.

The UN has estimated that meeting health needs, adapting farming and infrastructure, and so on will cost $70 to 100 billion a year by 2030. Now Martin Parry of Imperial College London says this “back of a metro ticket calculation” ignores major sectors, including energy generation and manufacturing, as well as the costs of protecting people from inland flooding and …