The Heat Will Kill You First: Life and Death on a Scorched Planet

by Jeff Goodell

Like aloe and other succulents, corn evolved in a warm place. Its wild ancestor, a grass called teosinte, thrived for ten thousand years in the Balsas River Valley in south-central Mexico, where the temperature is a steady 80 degrees. That means that deep in its ancestral gene pool, it has more tools to handle heat than many plants. But 80 degrees is very different than, say, 102 degrees. As the world heats up, corn is nearing the limits of its adaptive (or “permissive”) temperature range. To put it another way, it’s already growing in hot places and now those places are getting hotter. Add a modest heat wave to those already hot places and corn has trouble coping. Add an extreme heat wave and it may not recover at all. Corn is in particular trouble if that heat wave hits during the reproductive cycle. “Heat disrupts the development of the pollen tube, which is deployed from the pollen to deliver the sperm into the female plant’s ovule,” plant scientist Donald Ort told me. “So the plant never fertilizes, there is no ear.” Corn is also vulnerable because, at least here in the US, big seed companies like Monsanto and BSF have had their way with the corn genome for years. Growing it requires huge amounts of nitrogen fertilizers, which end up polluting rivers and lakes, causing huge algae blooms. In the right conditions, commercially bred corn is a superstar. But if heat spikes and rains don’t come at the right time, it’s vulnerable. In the highly engineered varieties of corn ...