Rising suicide rates in Mexico and the United States seem to be associated with increasing temperatures in those countries.

Marshall Burke at Stanford University in California and his colleagues examined decades’ worth of climate and mortality records in thousands of US counties and Mexican municipalities. They found a small but statistically significant correlation between temperature increase and suicide rate, even after factoring in the possible influences of poverty, handgun possession and other socioeconomic factors. In the adjusted data, a 1°C rise in average monthly temperature was associated with an increase in the monthly suicide rate of 0.68% and 2.1% in the United States and Mexico, respectively. The correlation exists in both warmer and cooler regions.

If climate change is not mitigated, between now and 2050 the United States could incur 14,000 more suicides than would be expected without warming, and Mexico 7,500 more, the researchers say.