Liquid assets

From John Lowe I quickly became indignant at your leader (22 February, p 5) implying that UK flood defences cannot be given any priority because they would cost unspecified large amounts of money. Reading further, your special report (p 8) puts the figure of £500 million over four years as a requisite. Compare this with the oftquoted £30 billion for the planned high-speed rail link HS2, which has a habit of gaining a round number of billions depending on which publication you read. It seems to me that we would do much better to scrap this white elephant and spend money on other infrastructure, of which flood defences are an important part. Chesham, Buckinghamshire, UK From Michael Bailey Adam Corner writes that “definitive proof that this weather is the result of climate change is currently beyond us” (22 February, p 28). As a retired statistician, this “currently” worries me more than a little. How can we ever definitively prove a single weather episode was caused by anything? If my uncle Bill died of lung cancer after smoking 60 cigarettes a day for 40 years,  we can’t say that the cigarettes caused his cancer. What we can definitely say is that smoking raises the probability of getting lung cancer. It seems that many people can’t, or won’t, accept that much of our scientific knowledge is about probabilities. We’re as certain of climate change raising the probability of extreme weather events as we will ever be. Uki, New South Wales, Australia