THE EFFECTS OF CLIMATE CHANGE ON MENTAL
HEALTH
by
SARAH SLOAT
_________________________________________________________________
Sarah
Sloat a senior staff writer at Inverse (www.inverse.com).
She has previously written for The New Republic, Pacific Standard,
and McSweeney's Internet Tendency.
A landmark
United Nations report revealed that catastrophic events induced
by climate change could become regular occurrences as soon as
2040. In the report, the UN’s Intergovernmental Panel on
Climate Change predicts disastrous effects around the world if
greenhouse gas emissions continue to increase at their current
rate. Previously, scientists believed these severe consequences
would happen if the planet warmed by 2 degrees Celsius; now, the
threshold is only 1.5. Another related study, highlights the extreme
toll climate change has already taken on the human psyche, 22
years before the 2040 warning.
Short-term
exposure to extreme weather, multi-year warming, and tropical
cyclone exposure are all associated with worsened mental health,
scientists affirm in the journal Proceedings of the National Academy
of Sciences.
“Our
paper — when coupled with evidence that climate change may
impact everyday human moods to severe outcomes like suicide —
provides further evidence that exposure to heat, on average, worsens
mental health outcomes,” study co-author and MIT Media Lab
research scientist Nick Obradovich, Ph.D., tells Inverse. Obradovich
and his colleagues reached this conclusion by analyzing the mental
health data of nearly 2 million Americans, as well as daily meteorological
and climatic data taken between 2002 and 2012.
“If we push global temperature rise into the 2 degrees-plus
Celsius range, the impacts on human well-being, including mental
health, may be catastrophic,” he says.
Between
2002 and 2012, approximately 2 million individuals reported the
state of their mental health through the US Centers for Disease
Control and Prevention’s Behavioral Risk Factor Surveillance
System. Each respondent was asked to report how stress, depression,
and “problems with emotions” affected their mental
health over a period of 30 days. When Obradovich and his colleagues
evaluated those responses alongside data concerning multi-year
warming, they discovered that, on average, monthly temperatures
hotter than 30 degrees Celsius — or 86 degrees Fahrenheit
— were associated with more reports of mental health difficulties,
as compared to temperatures closer to 10 to 15 degrees Celsius
— or 50 to 59 degrees Fahrenheit.
They
also found that months with more precipitation days amplified
the probability of experiencing mental health issues. Overall,
months with more than 25 days of precipitation increased the probability
of mental health issues by 2 percentage points, compared to zero
monthly precipitation. The connection here may not be obvious,
but climate change is linked to increased precipitation because
rising temperatures intensify the Earth’s water cycle and
increase evaporation. Increased evaporation results in more storms,
and places with more storms experience an increase in precipitation.
Overall, the average US precipitation has steadily increased since
1900.
Importantly,
the effect that monthly temperatures have on mental health is
worse for women and low-income individuals. The team determined
that low-income respondents were 60 percent more likely than the
highest-income adults to develop mental health issues when temperatures
exceed 30 degrees Celsius. The same negative effects are seen
in female respondents, who experienced mental health issues at
a 60 percent greater rate than the men in the sample during high-temperature
months.
This
is in line with established findings that demonstrate that the
world’s communities that are most vulnerable to exploitation
and oppression are also the most susceptible to the impacts of
climate change. Here, the study authors note that even though
they found these effects, they were already pulling data from
a wealthy country with a temperate climate. They note that “regions
with less-temperate climates, insufficient resources, and a greater
reliance on ecological systems may see more severe effects of
climate change on mental health.”
And while
this study’s results may be troubling, it’s not the
first time scientists have established the impact climate change
has on mental health. Previous studies have found that heat and
drought amplify the risk of suicide and psychiatric hospital visits,
and the American Psychological Association determined in 2017
that climate-induced stress is likely to worsen stress-related
problems, like substance abuse and depression. However, the exact
reason climate change induces poor mental health is difficult
to say.
“We
can’t be sure,” Obradovich admits. “It could
be via the impacts of heat on sleep, on daily mood, on physical
activity rates, on heat-related illness, on cognitive performance,
or any complex combination of the above. Unfortunately, these
processes are so complex that we can’t easily identify precisely
which mechanism is driving our results.”
But in
some cases, the reasons that a climate-change-induced event could
harm mental health are more obvious: In this study, the team found
that experiencing the havoc of Hurricane Katrina led to a 4 percentage
point increase in experiencing mental health issues. Hurricane
Katrina was one of the worst disasters in U.S. history, which
left as many as 600,000 households displaced.
In a
hopeful twist, one of the caveats the authors of this paper note
about their work is that these observed effects may not persist
into the future. Humans, they write, could adapt “technologically
and physiologically to warmer climates,” and we could also
adapt via “psychological coping mechanisms, such as avoidance,
seeking social support, or fostering mental preparedness.”
It’s
a nice thought, as long as avoidance doesn’t mean ignoring
the facts.
