As the planet continues to warm, you can expect more droughts, more flooding, more powerful storms, and, apparently, more suicides. That's according to Stanford researchers who scoured data on 850,000 suicides in the US between 1968 and 2004 and 611,000 suicides in Mexico between 1990 and 2010. They see a link between temperature increases and increases in the suicide rate. Specifically, the suicide rate increased 0.7% in the US and 2.1% in Mexico when the average monthly temperature was 1 degree Celsius higher than normal. That was true across income levels regardless of whether the temperature rose in January or July, in hot or cold climates. "It's sort of a brutal finding," study author Marshall Burke tells the Atlantic, with the Guardian describing expected burdens on wealthy countries where suicide rates are already high.
Unless greenhouse-gas emissions are reduced, Burke predicts this link between suicide and temperature will result in another 14,000 to 26,000 US deaths by suicide by 2050, a change equal to "the estimated impact of economic recessions," according to the study published Monday in the journal Nature Climate Change. The link itself dates back to century-old observations of increases in suicide in summer months, but it remains little understood. As use of depressive language on Twitter was also found to increase with the temperature, Burke—who co-authored a 2013 study suggesting a similar effect on interpersonal violence—suggests "there's a plausible biological linkage between temperature, thermal regulation and how the brain regulates its own emotion," per CNN. If a solution can be found, "it has to be unprecedented," he tells the Atlantic. (Read more suicide stories.)