According to recent polling, climate change is seen as the single most threatening international challenge around the world, and there’s evidence that all that worry is taking a psychological toll. Adding to droughts, floods, extreme weather, and die-offs, psychologists are observing higher levels of anxiety, depression, and post-traumatic stress disorder in certain areas and professions. Even people who do not actively stress about global warming or view it as a major threat may still suffer psychological trauma from its effects.

Studying Doomsday

One group most directly affected by this phenomenon is climate scientists and advocates. For scientists, repeatedly observing life-altering climactic changes and predicting doomsday scenarios can contribute to a type of anxiety and depression that some are referring to as “climate trauma.”

“I don’t know of a single scientist that’s not having an emotional reaction to what is being lost,” said award-winning biologist Camille Parmesan in a National Wildlife Federation report. “Some of these people have been studying a particular reef or a particular bird or a particular mammal for 40 to 50 years and to start seeing it die off is a very hard thing.”

Climate scientists can experience fear and hopelessness when faced with such an existential threat on one hand and apathy or outright hostility from the public and policymakers on the other.

Some receive death threats on a regular basis, as in the case of Michael E. Mann, creator of the “hockey stick” graph. “On one occasion, I had to call the FBI after I was sent an envelope with a powder in it,” Mann told The Guardian. “It turned out to be cornmeal but again the aim was intimidation… That is the life of a climate scientist today in the U.S.”

Parmesan left the United States in part to avoid having to spend lectures convincing the audience that climate change was real in the first place, according to Grist. Compared to other threats, the U.S. public is the least concerned about climate change of any major region in the world.

Yet climate change can still have psychological impact on those not directly involved with the environmental field. In 2007, the first case of “climate delusion” was diagnosed when a 17-year-old Australian was hospitalized after refusing to drink water for fear of contributing to the country’s drought.

A Lasting Impact

Climate-related disasters can have a direct mental health impact when loss of life and property occurs. Research has connected extreme weather events such as floods, heat waves, and cyclones to reactions of extreme anxiety.

Participants in a 2009 study published in Health & Place used the words “horrifying,” “panic stricken,” and “petrified” to describe their initial reactions during the 2005 flooding of the city of Carlisle in the United Kingdom. Some experienced panic attacks, insomnia, low motivation, and obsessive behavior well after the disaster. This experience is typical among disaster survivors; while the disaster itself may be acute, anxieties can have long-term effects, developing into chronic depression, post-traumatic stress disorder, aggressive behaviors, and even suicide.

Long-term climate changes can also prompt psychological symptoms, including increased likelihood of developing chronic anxiety disorders, depression, and substance abuse. Sustained droughts increase the risk of suicide among male farmers, according to one study in New South Wales, Australia.

As physical and mental health share a causal, reciprocal relationship, climate change can also inflict indirect harm on mental health through damaging one’s physical well-being. Mental health can be compromised in the case of impaired fetal development, physical injury or trauma, asthma or allergy risk, heat-related illness, or increased exposure to pests, disease, and toxins.

Changes in the physical environment triggered by climate change can have psychological effects, such as proliferating vector-borne disease, respiratory illness from poor air quality, and changes in food and water quality and availability. To some communities, particularly those with cultural, religious, or identity-based roots in the natural world, dramatic damage to the Earth’s landscape alone can cause significant distress.

In all, the National Wildlife Federation estimates 200 million people in the United States alone will be exposed to serious psychological trauma from climate-related disasters in the coming years.

Vulnerable Communities

Psychological symptoms are especially likely amongst people exposed to climate disasters more than once. Those regions most vulnerable to climate change are also those with the least amount of human resources and access to mental health care. Worse, these areas are also the poorest.

According to a report by the American Psychological Association, the most vulnerable communities are the most impoverished and particularly women, children, and the elderly. A study in Australia found that following the 1974 Brisbane floods a significant number of new psychiatric symptoms occurred, with the greatest suffering among women and those between 35 and 75 years of age.

Another study in the United States found that recently arrived immigrants, migrants, or refugees are particularly vulnerable to the psychological impacts of climate change as these groups are most vulnerable to disruptions in services that disasters can affect, like shelter, nutrition, and safe drinking water.

Communities are even more susceptible to trauma following a disaster if few income-earning opportunities are available. Those no longer able to be employed by climate-dependent sectors, such as farming and fishing, may experience significant occupational identity loss. Being forced to move has significant psychological impacts as well.

Adaptation strategies, either forced or voluntary, can create distress themselves. In one study, residents moved to make way for China’s Three Gorges Dam underwent significant levels of distress compared with other people in the region. These challenges are compounded by an extreme shortage of mental health resources. Not only did results from the Three Gorges study show elevated levels of depression, but migrants had poorer access to social and psychological resources than their counterparts to deal with these changes.

While nearly 1 in 10 people suffer from a mental health disorder, there is less than 1 mental health worker for every 100,000 people in low-income countries, according to the World Health Organization. While comparisons between 2005 and 2011 show a slight gain in human resources, this occurred in mainly mid- and high-income countries while lower- and lower mid-income countries experienced a decline. The availability of beds in mental health hospitals decreased worldwide on average.

A Balancing Act

Although psychologists urge caution about creating pathologies out of normal reactions to disasters, they hold that there is a compelling case for further assessing the impact of climate change on mental health.

The American Psychological Association provides a list of tips to engage the public on climate change without causing undue distress. These include communicating specific solutions, acknowledging emotions toward climate change, focusing on local conditions and customs, and exercising caution when using vivid imagery.

This raises a question for advocates, however: How do you prompt action and concern about climate change without using vivid imagery?

If climate change messaging becomes so extreme that it instills hopelessness and implies that the situation is irreversible, some may see no reason to make short-term sacrifices to address it, writes Andrew Fiala of California State University, Fresno. At the same time, downplaying the seriousness of the situation may fail to spark engagement.

“Voluntary participation in collective action that requires individuals to sacrifice short-term self-interest is only rational when there is a perceived balance between the sense of crisis and the hope for a solution,” Fiala says.

Reaching such a balance seems to not only be a political, social, and environmental imperative, but a matter of individual mental health too.