So far, July is running a couple of degrees warmer than normal in these parts, MPR meteorologist Paul Huttner told Tom Crann on All Things Considered last evening and a new study suggests we’ll be needing to pay even more attention to the warming trend, which is no longer debatable.

The research from Stanford University scientists says the warmer temperatures will lead to more suicides.

The team has looked at data back to the ’60s, and factored in confounding things like air conditioning, income level, and gun ownership, and it has found that a monthly rise in temperature of 1 degree Celsius leads to “about a 1 to 2 percent increase in the suicide rate,” says Dr. Marshall Burke, assistant professor of earth system science at Stanford, as reported by WBUR.

The team also wanted to explore the link between temperature and mental well-being generally, not just suicide. In order to do this, they turned to Twitter, where they analyzed “nearly a billion tweets,” says Burke. After looking at how often the location-tagged tweets used depressive language as well as the temperature of the areas tweeted from, the scientists found “a pattern that’s strikingly similar” to the suicide data, Burke says: Higher temperatures meant worse mental health. Unlike some results of climate change that are mostly confined to coasts — like rising sea levels or increased hurricane intensity — Burke says poorer mental health will be a burden shared across populations. Since “everyone is going to experience temperature increases,” he says, “the toll from mental health could be incredibly large.”

The reasons are still uncertain.

“Hotter temperatures are clearly not the only, nor the most important, risk factor for suicide,” Burke said. “But our findings suggest that warming can have a surprisingly large impact on suicide risk, and this matters for both our understanding of mental health as well as for what we should expect as temperatures continue to warm.”

“We’ve been studying the effects of warming on conflict and violence for years, finding that people fight more when it’s hot. Now we see that in addition to hurting others, some individuals hurt themselves. It appears that heat profoundly affects the human mind and how we decide to inflict harm,” Solomon Hsiang, study co-author and associate professor at the University of California, Berkeley, said in a news release.

“It’s the most exhaustive study I know of that’s really looked at this relationship between temperature and suicidality in North America,” a Harvard doctor says. “Short of turning on and off the sun,” this paper does as much as possible to prove cause and effect.”