CLIMATE CHANGE IS AMONG THE GREATEST THREATS TO OUR MENTAL HEALTH, SCIENTISTS SAY. AND SCORCHING HEAT WAVES ARE A PARTICULAR WORRY. MEANWHILE, TRUMP SAYS CLIMATE WILL ‘CHANGE BACK AGAIN.’
It was Raymond Chandler who wrote of nights with a hot wind blowing into Los Angeles — a wind that makes “your nerves jump.”
“On nights like that every booze party ends in a fight,” he wrote. “Meek little wives feel the edge of the carving knife and study their husbands’ necks. Anything can happen.”
Now there’s research that says climate change may damage our mental health, just like Chandler’s hot wind from the Santa Ana Mountains.
Last week, a team of 28 specialists convened by the Lancet medical journal listed climate change among the greatest threats to mental health globally.
Ferocious storms and more frequent weather extremes will affect the human psyche in costly ways, some scientists predict, from more depression and anxiety to increased suicide rates.
Scorching heat waves are a particular worry.
One working theory is that some of the same neurotransmitters used by the brain to regulate the body’s temperature are also used to control emotions. The more neurotransmitters needed to cool the body, the less available to suppress emotions like aggression, impatience or violence.
It’s also possible climate change will cause hotter nights in some regions, and that will mean less sleep. Serious sleep deprivation is a risk for depression and suicidal thinking.
Whatever the possible mechanism, “sound mental health — a critical facet of human wellbeing — has the potential to be undermined by climate change,” researchers report in the journal PNAS.
Humans have already driven up the Earth’s temperature by about 1 degree Celsius globally, and the newest report from the Intergovernmental Panel on Climate Change (IPCC) says utilities would have to cut coal consumption to a third of current levels by 2030 to keep warming under 1.5 degrees Celsius.
Over the past decade, researchers have warned global warming is likely to amplify natural disasters that can cause serious bodily harm — drownings from typhoons, famine-causing droughts, and heat-related deaths like the 80 who died from extreme heat in Quebec in July. And a 2017 study linked crop-damaging temperatures to increased suicide rates in India.
In July, a Stanford University-led team reported that hotter weather increases both suicide rates and the use of “depressive language” on Twitter — words like “I feel lonely,” “trapped” or “suicidal.” The team compared historical temperature and suicide data across thousands of U.S. and Mexican municipalities over several decades, from 1968 to 2010. They also analyzed half a billion tweets. They found that suicide rates rise 0.7 per cent in the U.S. and 2.1 per cent in Mexico when monthly average temperatures increase by one degree.
The effect was similar in hotter versus cooler regions, and hasn’t diminished over time, despite the spread of air conditioning. The authors predict that, by 2050, climate change could cause more than 20,000 “excess” suicides in the U.S. and Mexico.
“We’ve been studying the effects of warming on conflict and violence for years, finding that people fight more when it’s hot,” coauthor Solomon Hsiang, of the University of California, Berkeley, said in a statement released with the study.
“Now we see that in addition to hurting others, some individuals hurt themselves. It appears that heat profoundly affects the human mind.”
The authors were quick to add that heat, alone, isn’t the only risk factor for selfharm. And it’s not clear if hot temperatures hasten suicides that would have happened anyway.
It’s not likely someone becomes severely depressed solely because it’s really hot outside. Most mental illnesses have their roots in childhood and adolescence, the Lancet Commission paper says. Still, studies in the U.S. and South Africa have linked hot temperatures with increased rates of violent crime, robbery and assault. Others have found heat increases circulating levels of the stress hormone, cortisol.
While the Lancet report focuses on indirect ways climate change affects a per- son’s mental state through natural disasters, “not everywhere is facing an increased risk of cyclones due to changes in hurricane patterns,” said Tamma Carleton, a postdoctoral scholar with the Climate Impact Lab at the University of Chicago. “But virtually everywhere around the world we’re facing warmer temperatures, and there is a lot of evidence of direct effects of warming on mental health.”
In the most recent study published in PNAS, researchers linked self-reports of mental health from nearly two million randomly sampled U.S. residents with daily meteorological data between 2002 and 2012.
Their measure of mental health came from Centers for Disease Control and Prevention surveys that asked: “Now, thinking about your mental health, which includes stress, depression and problems with emotions, for how many days during the past 30 days was your mental health not good?”
The researchers found that, all else being equal, shifting from monthly temperatures between 25 C and 30 C, to more than 30 C increased the probability of someone reporting mental health difficulties by 0.5 per cent.
However, Canadians experience more depression in winter than summer months, and depression increases with latitude, the University of Calgary’s Dr. Scott Patten said. As well, the PNAS study relied on a single, broad, catch-all question related to mental health.
Patten, an expert in the epidemiology of mood disorders, said that while he doesn’t doubt that any source of stress — including extreme heat or extreme weather, and the economic hardships that can come with them — would have negative effects on a person’s mental health, he finds it hard to accept some of the projections.