The effects of climate change on mental health and wellbeing are documented. This is especially the case for vulnerable populations and those with pre-existing serious mental illness. There are three broad pathways by which these effects can take place: directly, indirectly or via awareness. The direct pathway includes stress-related conditions caused by exposure to extreme weather events. These include post-traumatic stress disorder (PTSD). Scientific studies have linked mental health to several climate-related exposures. These include heat, humidity, rainfall, drought, wildfires and floods. The indirect pathway can be disruption to economic and social activities. An example is when an area of farmland is less able to produce food. The third pathway can be of mere awareness of the climate change threat, even by individuals who are not otherwise affected by it.
An additional aspect to consider is the detrimental impact climate change can have on green or blue natural spaces, which in themselves have been proven to have beneficial impact on mental health. Impacts of anthropogenic climate change, such as freshwater pollution or deforestation, degrade these landscapes and reduce public access. Even when the green and blue spaces are intact, access to them is not equal across society, which is an issue of environmental justice and economic inequality.
Mental health outcomes have been measured in several studies. These use indicators such as psychiatric hospital admissions, mortality, self-harm and suicide rates. People with pre-existing mental illness, Indigenous peoples, migrants and refugees, and children and adolescents are all vulnerable. The emotional responses to the threat of climate change can include eco-anxiety, ecological grief and eco-anger. Such emotions can be rational responses to the degradation of the natural world and lead to adaptive action.
Assessing the exact mental health effects of climate change is difficult; increases in heat extremes pose risks to mental health which can manifest themselves in increased mental health-related hospital admissions and suicidality.
Pathways
Mental health is a state of well-being where an individual can recognize their abilities, handle daily stresses of life, productively work and be able to contribute to their community. There are three main causal pathways by which climate change impacts mental health: directly, indirectly or via awareness (or "psychosocial"). In some cases, people may be affected via more than one pathway at once. Various studies use different nomenclature to designate the three causal pathways. e.g. some designate the "awareness" pathway using the term "Indirect impact," while grouping "indirect effects" via financial and social disruption under "psychosocial".
Impacts from direct pathway
The direct pathway includes stress-related conditions being caused by exposure to extreme weather events, such as heat waves, droughts, floods and wildfires. These conditions can result in trauma-related events, such as dislocation from climate-change induced natural disasters, such as flooding or fire, losing friends and family, or other traumatic events. The effect of being exposed to such events can be increased mental health illnesses such as post-traumatic stress disorder and acute stress disorder, depression, and generalized anxiety disorder. These effects often occur simultaneously, as well as individually. A large amount of literature exists concerning the association between disasters and mental health (without explicitly linking an increase in frequency and severity to climate change).
Most commonly this is short term stress, from which people can often soon make a rapid recovery. But sometimes chronic conditions set in, especially among those who have been exposed to multiple events, such as post traumatic stress, somatoform disorder or long term anxiety. A swift response by authorities to restore a sense of order and security can substantially reduce the risk of any long term psychological impact for most people. Though individuals who already had mental ill health, especially psychosis, can need intensive care, which can be challenging to deliver if local mental health services were disrupted by the extreme weather.
Physical health can be severely impacted by climate change (see also effects of climate change on human health). The deterioration of a person's physical health can also lead to a deterioration in a person's mental health.