Alarmists might like to consider this too, though I doubt they will ... If all the world's leading nations stick to the carbon-reduction commitments they will make in Paris this week, then they will stave off "global warming†by the end of this century by 0.170 degrees C. Oh – and that's the optimistic scenario, calculated by Bjorn Lomborg, assuming that countries like, say, China don't lie or cheat about how much CO2 they're burning secretly. His more pessimistic – ie more realistic – scenario is that the best we can hope for is a reduction in global warming by the end of the century of 0.048 degrees C. This temperature reduction – five hundredths of one degree – is so small as to be almost immeasurable. But if you want to know what it feels like, Willis Eschenbach has done the calculations. It's the equivalent of walking five metres higher up a mountain. Or, if you prefer, climbing two flights of stairs. And there you have it: the lunacy of the Paris climate conference in one sentence: $1.5 trillion every year till the end of the century to effect the equivalent of walking to your bedroom.