A new study published by Nature Climate Change journal found that 37 percent of heat deaths are due to climate change, the AP reports. Researchers studied the number of heat deaths in 732 cities from 1991 to 2018, and found that about 9,700 of those cases were directly caused by climate change. South America has the highest amount of global warming-related heat deaths, and São Paulo, Brazil, led with 239 a year. In the U.S., 35 percent of heat deaths were due to the climate crisis, with Honolulu, Hawaii, having the most.