Hindering harvests

摘要

THE problems climate change looks likely to bring in the future may increasingly be visible in the records of the past. Not just in the far-off ages of surging sea levels following ice-age thaws, spikes in prehistoric temperatures correlated with natural releases of greenhouse gas and ancient civilisations brought low by drought, but in records from living memory-which are based on reliable measurements made at the time. Using such data researchers have now compiled an estimate of global changes in crop yields which can be put down to recent increases in temperature and decreases in rainfall (the world as a whole is getting wetter, but the rain has stayed away from some agricultural plains). The bad news is that they find that climate change has lowered the amount of maize (or corn, if you prefer) and wheat produced in a given area. The good news is that the effect is so far reasonably small.