Absolutely love the new campaign from the Optimum Population Trust: do your bit for addressing climate change by having fewer children - or even no children. The lifetime CO2 emissions of a UK citizen amount to 750 tonnes (the equivalent - apparently - of 620 return flights between London and New York), so the extra 10 million by which our population will rise between now and 2074 will, over their lifetimes, emit around 7½ billion tonnes of CO2..."births averted" is probably the most single most substantial and cost-effective intervention that governments could be using