As one example of how disasters made more likely by climate change can affect mental health, the report cites statistics from people who survived Hurricane Katrina. Their rates of suicide and incidence of suicidal thoughts more than doubled, 1 in 6 people met the diagnostic criteria for PTSD, and nearly half of the people living in an affected area developed an anxiety or mood disorder such as depression.
“I found this topic really interesting because this wasn't something I was hearing people talk about and this wasn't well acknowledged as an effect of climate change,” said Susan Clayton, the lead author of the report and a professor of psychology at the College of Wooster in Ohio.
Some things can protect people from the worst psychological effects of climate-change-induced natural disasters, such as having social support. In contrast, those who live in communities where livelihood is directly tied to the environment, such as agriculture, tourism or fishing, are more vulnerable to negative mental-health impacts, according to the report. People in indigenous communities are particularly vulnerable because climate change can threaten environmental aspects of their cultural heritage.
Climate change can be a cause of stress, which is often caused by a sense of a loss of control or an inability to adapt to a new situation. Increased stress levels can increase the likelihood of problems such as substance abuse, anxiety disorders or depression, according to the report.
Problems exacerbated by climate change have carry-over effects on a person's physical health, the economy and the community. Changes in weather patterns can affect agriculture and infrastructure, which may force some people to migrate.
Displacement because of natural disasters can lead to a variety of negative consequences, such as a loss of social support, strains on personal relationships, absences from work and higher medical costs, according to the report.
The weather people experience also influences their mental health, the report says. Prolonged exposure to warmer weather makes people more aggressive and diminishes cognitive functions, according to earlier studies.
The authors of the report suggest several strategies people can use to cope with or mitigate the negative mental impacts of climate change. The most important thing is to encourage social connections, Clayton said, to make people feel more secure and give them greater access to information. Preparedness is another important factor in mitigating mental health effects caused or aggravated by climate change.
“The fact that most of us ignore climate change paradoxically makes the effects worse because we don't really know what to expect and it seems scary and unknown,” Clayton said, “but if we inform ourselves that that's what is likely to happen in our area, we would be more prepared and in control of the situation.”