Climate change and its impact on mental health

Although internationally climate change and its impact on human survival is increasingly being talked about with endless summits and agreements between politicians representing various countries but actions to deal with it seem to keep getting delayed or postponed on the flimsiest of excuses. There have been discussions about the impact of climate change on survival of humanity and also its effect on health, but as always mental health largely gets ignored although it appears that in the past few years this is beginning to change. In these circumstances, development of a new discipline within psychiatry—that of geopsychiatry—is particularly welcome. Geopsychiatry aims to look at geographical, political and commercial determinants and in turn their impact on social determinants which affect mental health and wellbeing. Furthermore, the field looks at wars, conflicts, natural and manmade disasters and their impact on mental health of individuals and communities. These disasters include climate change and its ongoing impact on mental health. These factors are international as often they occur across nations, whereas social determinants are more likely to be intranational.

Climate change is indeed a major health challenge across international and geographical borders but perhaps more importantly the speed of change is worrying to say the least. The impact of climate change occurs and is seen at different levels with varying consequences as illustrated later in this paper with profound implications for the future of psychiatric disorders. Research evidence indicates that extreme weather events, rising temperatures, and environmental degradation contribute very strongly to various psychiatric disorders. These include newer ones such as eco-anxiety, climate anxiety, solastalgia, etc. and older established ones such as depression, posttraumatic stress disorder, and suicide risk. Many vulnerable groups such as women, older adults, children and those with intellectual disability are further prone to developing climate change related psychiatric disorders. Climate change is not a homogenous phenomenon and includes various components such as air pollution, droughts, famines, flooding, etc., leading to increased migration within the country and across international borders. Climate change is leading to more frequent and extreme weather events which can have a traumatic impact on populations. It is worth noting that not everyone will be affected in the same way. People are affected in multiple ways and with specific support systems may respond in different ways so the healthcare professionals must be sensitive to that.

There is an urgent pressing need to look at the impact of climate change on different levels but before we do that it would be helpful to be clear about certain definitions.

According to the United Nations (not dated) climate change refers to long-term shifts in temperatures and weather patterns. As the document notes, these shifts and changes can be natural, due to changes in the sun’s activity or large volcanic eruptions. Over the past two centuries and more, this change is directly attributable to human activity primarily due to the burning of fossil fuels like coal, oil and gas [1]. Burning fossil fuels generates greenhouse gas emissions that trap the sun’s heat, raising temperatures. IPCC [1] reports that the main greenhouse gases causing climate change include carbon dioxide and methane. There are multiple sources of these from using gasoline for driving a car, air travel, burning coal for heating buildings, and methane produced by animals such as cows. In addition, destruction of forests, contribution of forest fires, etc. can further add to the greenhouse effect. Energy, industry, transport, buildings, agriculture and land use are among other factors that can contribute to greenhouse gases.

The impact of climate change on health including mental health and public health is important to be recognized and clearly depends upon type of event. Some are acute events and then there are ongoing chronic activities such as air pollution. There is a growing body of robust scientific evidence which confirms that global warming and extreme weather events affect health (including mental health) and such effects can be short-, medium- and long-term and these effects can be profound. However, in terms of any actions, certainly there is much left to be desired.

Palinkas and Wong [2] classify three types of climate-related events which have an impact on mental health and wellbeing. These include the following: (1) acute events such as hurricanes, tsunamis, typhoons, floods, and wildfires; (2) subacute or long-term changes such as drought and heat stress; and (3) the existential threat of long-lasting changes, which may lead to higher temperatures, rising sea levels and a permanently altered and potentially uninhabitable physical environment. The impact of these events on health can be both direct (i.e., heat stress) and indirect (i.e., economic loss, threats to health and wellbeing, displacement and forced migration, collective violence and civil conflict, and alienation from a degraded environment) consequences of global climate change.

Severe weather events—such as floods, droughts, wildfires, and heatwaves—are significantly associated with increased prevalence of certain psychiatric conditions as mentioned above. Climate change impacts at various levels: these include at individual, family, community, local, regional, national and international levels. And the response at each level will be different and possibly complex. These consequences can be caused by but also lead to forced involuntary acts of migration, loss of status, stress, psychiatric disorders, etc, which further add to loss of emotional stability, sense of belonging, and the psychological wellbeing of entire communities (see Figure 1). In this context, climate change emerges as a salient contributor to what has been described as “polycrisis.” This situation reflects a convergence of interdependent crises that collectively undermine human capabilities, long-term prospects, and overall wellbeing. This further brings complexity to an already complex field where socio-psycho-bio-spiritual-anthropological factors contribute to etiology of various psychiatric disorders as well as therapeutic interventions. Various authors have argued persuasively for prioritizing preventive and adaptive interventions [3‐5]. These factors are likely to have major and serious impact on design and delivery of psychiatric services.

In a systematic review, Walinski et al. [6] studied both the direct effects of acute extreme weather events (floods, storms, fires) and chronic stresses (heat, drought) due to climate change, and the indirect effects of climate change (food insecurity, migration), on the diagnoses of mental disorders, psychological distress, and psychiatric emergency admissions. Not surprisingly, they found that heterogeneity of studies and data were problematic, but they concluded that the traumatic experiences due to extreme weather events increase the risk of affective and anxiety disorders, especially the risk of posttraumatic stress disorder. This also seemed related to heat (high temperatures) which further increased the morbidity and mortality attributable to mental illnesses and psychiatric emergencies. In addition, continuing environmental challenges related to draughts, food insecurity and consequent migration contributed to the likelihood of higher rates of psychiatric disorders.

In a scoping review, Charlsson et al. [7] also reported that several climate-related exposures, including heat, humidity, rainfall, drought, wildfires, and floods were associated with psychological distress, worsened mental health. They also found that these changes were associated with higher mortality among people with pre-existing mental health conditions, increased psychiatric hospitalizations, and heightened suicide rates.

IPCC [8] have noted that virtually all global heating over the last 200 years largely has been due to greenhouse gases that are warming the world faster than at any time in at least the last two thousand years. WMO [9] has indicated that the temperatures are higher than befor, with the last decade being the warmest on record [9]. However, it needs emphasizing that temperature rise is only one aspect of climate change because its causes and consequences are both complex and important in our understanding what is happening to the planet as a system. The systems approach is important because of the interconnectedness of countries, environments, trade, climate, etc. and thus the slightest change in one area can influence changes in all others leading to the aphorism that when a butterfly flaps its wings in one part of the world, typhoons can occur in another part. Intense droughts, water scarcity, forest fires, rise in sea levels, flooding, melting icebergs, storms, tsunamis are all interconnected but quite often focus is on or the other rather than in an interconnected way.

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The World Health Organization (WHO) [10] has estimated that between 2030 and 2050, climate change is expected to cause approximately 250,000 additional deaths per year, from undernutrition, malaria, diarrhea and heat stress alone. WHO reckons that the direct damage costs to health (excluding costs in health-determining sectors such as agriculture and water and sanitation) is estimated to be between US $ 2–4 billion per year by 2030. We know that health including mental health is interlinked with housing, employment, education, food, etc. and as climate change will affect ability to grow food, housing, safety and work, rates of various psychiatric disorders are likely to rise. With rising sea levels there is an imminent danger that many island nations such as Maldives, Barbados and other places may well submerge under water. On the other hand, many countries in the global south may be vulnerable to water scarcity and droughts. These conditions are likely to push people into migrating internally as well as across borders.

The emissions that cause climate change come from every part of the world and affect everyone. However, countries such as the USA and emerging markets such as China, Brazil and India are high polluters [11]. Action points recommended by the United Nations (UN) and various agreements such as Paris agreement will not be repeated here. Suffice it to say without being unduly alarmist and pessimistic, that unless drastic measures are taken to cut emissions, the situation does look bleak. There are relatively accessible solutions such as switching to clean energy and other appropriate sustainability measures provided there is political will. Complicating factors include lobbyists on behalf of interested parties from commercial sector, armaments, fossil fuel industries, etc.

Li et al. [4] caution that the climate and ecological crisis will constitute the defining public health challenge of the twenty-first century. This inevitably will include impact on mental health as physical and mental illnesses affect each other in a variety of ways. Thus, there is an unprecedented global threat to all determinants of health, and consequently to healthcare delivery systems with increasing demands and strain on the healthcare system.

As mentioned above, there can be direct and indirect impacts on mental health of individuals, families and communities. Extreme weather events, like typhoons, tsunamis, hurricanes and floods, can cause psychological distress and trauma through loss of material possessions but also loss of support and bereavement. Furthermore, the impact can be on pre-existing conditions as well as developing new ones. In addition, survivor guilt may be seen in vulnerable individuals. Actual events as well as expected events may cause anxiety, depression, and suicidal ideation and acts of suicide. Air pollution and infectious diseases, which can be exacerbated by climate change, also have direct and indirect impacts on mental health and wellbeing of individuals. Newer categories of clinical diagnoses such as eco-anxiety, climate anxiety, eco-grief, solastalgia, etc. are beginning to emerge but need very careful study and evaluation.

At a broader level, such extreme weather events will affect determinants such as unemployment, loss of housing, food and water insecurity and other social consequences. Bonnano et al. [12] reported that most people following an extreme weather event can recover fully but it is worth being emphasizing that repeated events may affect subsequent ability to cope. Increasing temperatures and heat can lead to various psychiatric disorders as well as worsen the mental state of individuals with pre-existing psychiatric conditions. Burke et al. [13] demonstrated that rates of suicide increased when the temperatures went up. The cause and effect need further exploration although heat can produce sleep disturbances and negative thinking. Romanello et al. [14] reported variations across countries with a larger than expected effect in low-income countries. Another complicating factor that must be borne in mind is that many psychiatric medications can disrupt the person’s ability to regulate body temperature and contribute to sleep disturbances during heat waves.

Three areas of policy, research and clinical services require attention. Some of the recommendations are listed below.

The consequences of climate change are stress factors for mental health. Therefore, as global warming progresses, an increasing incidence and prevalence of mental illness is to be expected. Vulnerable groups, such as the (already) mentally ill, children, and adolescents, need to be protected. There is a need for further systematic research on the mechanisms of action and effects of climate change on mental function.

In view of the urgency of the impact of climate change and its consequences on the mental health and wellbeing of individuals, there is a pressing need to adapt psychiatric training, fortify healthcare infrastructure, and implement climate-responsive policies. Telepsychiatry and other digital interventions may be helpful in urgent assessments as well as ensuring continuity of care. Research on neurobiological stress markers may offer innovative pathways for prevention and early intervention. Psychiatry must play an active role in climate change mitigation and adaptation efforts, advocating for climate justice and equitable access to mental health services. Addressing the psychiatric dimensions of climate change is essential for building resilient mental health systems in the decades ahead.