Increasing concurrent exposure of global breadbaskets to reproductive heat extremes

In recent years, circumglobal heatwaves are becoming increasingly frequent, motivating concerns about the concurrent exposure of global breadbaskets to heat extremes during crop reproductive periods. Here we project the likelihood of concurrent exposure of global breadbaskets of staple crops to widespread reproductive heat extremes. We find that circumglobal reproductive extreme heat exposure would be an agriculturally relevant climate feature in the coming decades. By 2028‒2057 under the Shared Socioeconomic Pathway 5-8.5 (with approximately 2 °C warming above preindustrial levels), the probability of major breadbaskets of the world concurrently enduring at least 5 d of reproductive extreme heat over more than half of their croplands in a typical year is projected to rise from virtually unlikely to 0.43 for maize, 0.27 for wheat, 0.33 for rice and soybean. While as of 2050‒2079 (with approximately 3 °C warming above preindustrial levels), these probabilities would grow rapidly to 0.91, 0.83, 0.87, and 0.80, respectively. Should such dramatic increases in circumglobal reproductive extreme heat exposure occur, they could pose substantial stress on food production and agricultural adaptation, particularly when coinciding with agricultural droughts.