One key metric used by economists to measure the negative consequences of climate change is the number of “90-degree days” per year. A “90-degree day” is a day where the average of that day’s high and low temperature is at least 90 degrees. That is roughly the temperature level that turns out to be dangerous for both people and crops. But how dangerous? That depends on where you live. Michael Greenstone, co-director of the Climate Impact Lab, joined the podcast to talk about the social cost of carbon and the Lab's research on heat mortality.