Firms can use thermal imaging, for example, to see if crops are getting enough water. Thirsty crops tend to be a little warmer than others. That's because, normally, plants release some of the water they soak up through their roots out through tiny pores on the underside of their leaves. When that water evaporates, it cools off the plant, just as sweating cools off humans. Thirsty plants, however, close off these pores to avoid losing water, which leaves them a little warmer. If farmers can identify precisely which plants are parched, they only need to irrigate those crops, which helps them save water, which will become harder to come by as climate change fuels longer and more severe droughts.