Time to see the blight

摘要

RISING CARBON-DIOXIDE levels and the climate change associated with them portend many problems, but one group of people might be expected to give them a cautious welcome: farmers in Earth's temperate zones. More CO_2 typically results in more photosynthesis and therefore higher yields, and milder weather means longer growing seasons. Balanced against these potential benefits, however, is the potential for blight. It is hard to predict how changes in the climate and the atmosphere's chemistry will affect the prevalence and virulence of agricultural diseases (see Science section). But there is a risk that such changes will make some plant infections more common in all climatic zones, perhaps catastrophically so. To fend off this danger, seed companies and botanists need to band together to stockpile a genetic arsenal before it is too late.