The four horsemen of the human apocalypse, which cause the most premature and avoidable death in poor countries, are and will be for many years the same: hunger, dirty water, indoor smoke and malaria, which kill respectively about seven, three, three and two people per minute. If you want to do your fellow human beings good, spend your effort on combating those so that people can prosper, ready to meet climate challenges as they arrive. Economists estimate that a dollar spent on mitigating climate change brings ninety cents of benefits compared with $20 benefits per dollar spent on healthcare and $16 per dollar spent on hunger. Keeping climate at 1990 levels, assuming it could be done, would leave more than 90 per cent of human mortality causes untouched.