Rising Temperatures Linked to Slightly Higher Rates of Suicide in U.S. and Mexico

The relationship between climate change and mental health has been an active — and occasionally contentious — area of research in recent years. Now, a new study has found a link between above-average temperatures and small increases in suicide rates in the United States and Mexico.

The research, published this week in the journal Nature Climate Change, found that a 1-degree Celsius (1.8 F) increase in average monthly temperatures was associated with a 0.68 percent increase in the monthly suicide rate in the U.S., using county-level data from 1968 to 2004, and a 2.1 percent increase in Mexico, using municipality-level date from 1990 to 2010. Researchers also examined more than 600 million geotagged social media updates from 2014 to 2015 and found a link between higher average temperatures and increased use of depressive language on Twitter.

The scientists took into account factors such as seasonal variation, poverty levels, gun ownership rates, holidays, periods of economic growth or recessions, and even news of celebrity suicides. But the authors warn that the results of their study alone cannot be used to explain individual instances of suicides.

“Determining whether or not the rate of suicide responds to climatic conditions is important, as suicide alone causes more deaths globally than all forms of interpersonal and intergroup violence combined, and is among the top 10 to 15 causes of death globally,” lead author Marshall Burke, an expert on the social and economic impacts of environmental change at Stanford University, and his colleagues wrote in the new study.

Previous research has linked rising temperatures to increased suicide rates in India and increased rates of admissions for mental disorders in Australia.