It’s climate change again, innit. It didn’t take long for Sunday’s flooding in London to be put together with Canada’s recent heatwave and the floods in Germany and China to be used as ‘evidence’ of ever-accelerating climate change – giving us even less time to save the world than previously thought. ‘More rain as Londoners call out climate change,’ screamed a headline on City A.M., alongside pictures of water pouring through Stratford DLR station and cars stuck on the North Circular. Sunday’s flash floods have also brought an old favourite out of the closet: a map purporting to show large parts of London which will be underwater by 2030 – and which actually shows areas which would be threatened, even now, by extreme tidal flooding if London had no flood defences (which of course it does have).
But is it really climate change wot flooded your local bus stop? One of the latest wheezes of climate alarmists is to argue that warmer air contains more moisture, and to use that to try to link any flood event to global warming. It is true that warmer air has the capacity to absorb more water vapour (which doesn’t necessarily mean it does contain more moisture at any particular place and time), but then warmer air also means more evaporation, with the result that when it does rain, that rain is less likely to land on saturated ground – so it doesn’t follow that warmer air necessarily means more floods.
But more to the point, is there any evidence that Britain is actually experiencing heavier rainfall? Sunday’s rain certainly didn’t break any records. The most intense rain measured that day (not in London but in Bethersden in Kent) was 48.5 mm in an hour. The record for rainfall in an hour is almost twice this figure – 92 mm measured at Maidenhead as long ago as 12 July 1901.