Heat extremes and drought linked to global warming are already imposing a multibillion-dollar annual cost on three of the world’s most important crops, with new research estimating that climate-driven losses to maize, wheat and soybean production have amounted to roughly $400 billion over two decades. The analysis suggests that recent increases in extreme heat and drought have reduced yields by about 3.5% compared with an earlier climate baseline, a seemingly modest percentage that translates into enormous losses once applied across global agricultural markets.