Keywords

Climate change; physical health; wellbeing; mental health; vulnerable populations

9.1 Introduction

Climate change is no longer a distant, unimaginable threat; it is a growing reality for communities across the globe that are already experiencing its effects. Most people are aware of the many weather-system impacts of climate change. These include an increase in average temperature; rise in sea level; changes in patterns of precipitation, including increased intensity of storms in many places; and decreased availability of fresh water in many areas of the world (for a summary of climate change impacts, see the Fifth Assessment Report of the IPCC, 2014). What is less often considered are the subsequent impacts that these climate- and weather-related changes are likely to have on the resources, systems, and services people all over the world rely upon.

Recently, attention has begun to turn to the many ways that climate change will affect human health. A comprehensive review by the US Global Change Research Program emphasizes that all Americans will be impacted by the widespread impacts of climate change (USGCRP, 2016), and as global temperatures rise, people worldwide will increasingly be exposed to climate-related public health threats (Watts et al., 2015; Patz, Frumkin, Holloway, Vimont, & Haines, 2014). People will not only face direct health dangers from increasingly severe weather events, heat waves, and flooding due to rising sea levels but also be confronted by less obvious, but more widespread, indirect impacts of climate change such as an increase in diseases carried by pests, lower air quality, food insecurity, and disruptions to supplies of clean water (USGCRP, 2016; Watts et al., 2015).

In addition to impacting physical health, climate change will take a serious toll on mental health and wellbeing. Both the acute impacts of a changing climate, such as extreme storms, as well as the slowly building and chronic impacts, such as increasing drought, will impose significant stress on human beings, not only through immediate threat of death and injury but also from the long-term upheaval and uncertainty they will bring. For some proportion of individuals, their ability to cope with these changes may become overwhelmed, resulting in short-term or long-term stress, anxiety, substance abuse, depression, posttraumatic stress disorder (PTSD), and, in some cases, even suicide. Other effects will be manifest at the level of the community or the society, and may be represented not by obvious harms, but by a failure to achieve the quality of life that might have been attained in the absence of climate change.

This review describes the human health and wellbeing risks and impacts of global climate change, with a focus on mental health. We take a broad view of wellbeing, for health is more than simply the avoidance of disease and injury. Mindful of the interdependence between physical and mental health and the ways in which both can be affected by the social context, we include discussion of those indirect impacts of climate change that will affect interpersonal relationships, communities, and overall quality of life. To begin, we briefly review the physical health impacts discussed in the medical and public health literatures. We then turn attention to the mental health effects of climate change from both acute and chronic impacts and describe how certain vulnerable groups will be disproportionately affected. Finally, we discuss some of the lifestyle changes that are likely to come with a changing climate. The chapter will end with a brief discussion of the health co-benefits associated with taking action to mitigate climate change.

9.2 Physical health effects of climate change

The physical health threats of climate change will come through both direct and indirect pathways. Direct impacts are most easily identifiable in the case of extreme weather events. Extreme storms or flash floods may have high mortality rates, especially in communities that are unprepared. During extreme storms, there is an increased likelihood of acute physical trauma, such as being struck by debris or by building collapse (Alderman, Turner, & Tong, 2012), as well as an increase in traffic accidents (Leard & Roth, 2016). Drownings are likely during flash floods. The danger continues even after the flood or storm is over; acute events are generally followed by a cascade of other potentially significant impacts. For example, people may sustain nonfatal injuries such as cuts or broken bones or experience respiratory problems due to the growth of indoor mold. Floodwaters also bring the potential for indirect hazards, such as toxic materials from damaged industrial facilities or waterborne diseases (e.g., skin infections, gastrointestinal disease when hygiene resources are unavailable). In addition, disasters such as extreme storms or floods may lead to infrastructure failures, for example, power outages, breakdown in water, sewer, and other systems, or urban fires. Disruptions in emergency services or in local health-care systems may lead minor issues to escalate into major problems. Left unaddressed, major problems may become fatal problems. Disruptions in other types of services (e.g., cell phone communication or garbage and recycling services) create difficulty during the aftermath of an acute event and may affect physical health by making it impossible to access health care (without a phone) or by potentially increasing exposure to pests or hazardous substances (e.g., when there is no garbage pickup). At least one analysis found that survivors of Hurricane Katrina faced lingering challenges such as these even a full 5 years after the disaster (Hatch, Cherry, Kytola, Lu, & Marks, 2015).

A global rise in temperatures will also have direct effects on human health and mortality. In fact, more people die due to extreme heat than due to any other type of weather event in the United States (Portier et al., 2010). A recent analysis suggests that by the end of the century, at least 48%, and perhaps as high as 74%, of the world’s population will experience more than 20 days a year of “lethal” heat conditions compared to 30% today (Mora et al., 2017). Prolonged heat exposure is particularly hard on people with preexisting health problems as it can worsen cardiovascular, respiratory, and cerebrovascular diseases like diabetes and asthma (Portier et al. 2010).

Increased temperatures also contribute to some of the most profound indirect impacts on human health, such as respiratory troubles from exposure to increased ground-level ozone; asthma from rising pollen levels and higher particulate air pollution; and increased water-related illnesses caused by algal blooms, bacteria, or contaminated water, all predicted to increase due to climate change (USGCRP, 2016). Allergy season is likely to be more severe in many places due to a higher pollen count (Seeley, 2012), and climate change is also expected to increase the spread and toxicity of poison ivy (Mohan et al., 2006). Higher temperatures allow pathogen-carrying pests such as ticks, mosquitoes, and fleas—including the ticks carrying Lyme disease or the mosquitos carrying the West Nile virus—to expand their traditional range, exposing more people to the disease (USGCRP, 2016).

9.3 Mental health impacts from acute climate-related events

Physical and mental health are interdependent. Not only do extreme storms and other sudden weather events have a high potential to harm physical health, they may also cause immediate and severe psychological trauma. Trauma can stem from personal injury, injury or death of a loved one, damage to or loss of personal property (e.g., home) and pets, and disruption in work or livelihood (Neria & Schultz, 2012; Simpson, Weissbecker, & Sephton, 2011; Terpstra, 2011). The initial response to a disaster is usually characterized by emotions such as terror, anger, and shock (Raphael, 2007). In one study of people who had experienced a significant flood, people used words such as “horrifying,” “panic stricken,” and “petrified” to describe what it was like to live through the flood (Carroll, Morbey, Balogh, and Araoz, 2009 pg. 542; see also Tapsell & Tunstall, 2008).

According to a much-cited metaanalysis, some form of psychopathology was observed in between 7% and 40% of people who had experienced natural disasters (Rubonis & Bickman, 1991). Though general anxiety was most common, many other mental health problems were observed; phobic responses, somatic responses, substance abuse, and depression were all higher among disaster survivors compared to people in the general population, and rates were highest when measured directly after the disaster (Rubonis & Bickman, 1991). More recent studies and reviews find that acute traumatic stress, which is similar to PTSD but with shorter duration, is the most prevalent mental health problem immediately after a disaster, though anxiety, depression, and drug and alcohol abuse are also common (Fritze, Blashki, Burke, & Wiseman, 2008). Furthermore, in the aftermath of disasters, people are more prone to many behaviors that have a negative impact on their overall health and wellbeing such as smoking, risk-taking, and unhealthy eating habits (e.g., Beaudoin, 2011; Bryant et al., 2014; Flory, Hankin, Kloos, Cheely, & Turecki, 2009).

For most people, trauma symptoms decrease significantly after calm has been restored. However, many continue to experience some form of psychological difficulty for a significant time period after the acute event. A sense of troubling uncertainty can linger well after the initial disaster, and this adds an additional emotional stress burden (Lyon, Nezat, Cherry, & Marks, 2015). More significantly, PTSD, depression, general anxiety, and suicide can persist at higher levels even many months or years after a disaster. For example, within 5–7 months after Hurricane Katrina, approximately 15% of those directly impacted by the hurricane developed PTSD, and 49% of people living in affected areas developed an anxiety or mood disorder such as depression, even if they themselves had not been directly impacted (Galea et al., 2007; Kessler et al., 2008). According to Kessler et al., this compares to an expected PTSD prevalence of 1.4% among people with no hurricane-related stress. (Overall, approximately 27% of Americans suffer from an anxiety or mood disorder in a given year, and 3.5% suffer from PTSD, according to the National Institutes of Mental Health; this includes people who are experiencing other sources of stress. https://www.nimh.nih.gov/health/statistics/prevalence/index.shtml.) A year after the hurricane, anxiety disorders had not decreased, and PTSD and suicidal thoughts actually increased (Kessler et al, 2008). Similar mental health outcomes were found in communities that experienced Hurricane Sandy: 14.5% showed symptoms of PTSD 6 months later (Boscarino, Hoffman, Adams, Figley, & Solhkhah, 2014). A metaanalysis of studies examining the impacts of floods also found a clear increase in PTSD in flood-affected areas. Across the studies examined, higher reported levels of PTSD were linked to greater flood exposure (Fernandez, et al., 2015). Forest fires and bush fires, which are projected to rise due to the increase in dry conditions associated with climate change, have also been found to carry long-term psychological impacts. In one study of bushfire-impacted areas, 15.6% of a particularly hard-hit community showed symptoms of PTSD as many as several years after extreme bush fires (Bryant et al., 2014). As if the burden of PTSD were not enough, the disorder has been found to increase the likelihood of substance abuse, depression and anxiety, violence and aggression, interpersonal difficulties, and job-related difficulties (Simpson et al., 2011).

Many factors influence the likelihood that an individual exposed to trauma will later develop PTSD, such as that individual’s trauma history and the type of disaster they have experienced. As the studies described above indicate, PTSD is more prevalent in areas hardest hit by acute events. PTSD is also more likely among individuals who have experienced the kinds of losses that can never be recovered, such as the loss of close family members or significant property loss (Gerhart, Canetti, & Hobfoll, 2015; Wasini, West, Mills, & Usher, 2014). Furthermore, those who experience multiple acute events—for example, more than one disaster, or multiple years of drought—tend to show greater levels of psychological trauma and appear to be even more susceptible to PTSD (e.g., Edwards & Wiseman, 2011; Hobfoll, 2007). The impact of multiple acute events is particularly problematic if the disasters occur rapidly enough that there is little time to recover between. One study of refugees exposed to multiple acute events (e.g., more than one natural disaster, along with loss of loved one or other personal trauma) showed an increase in both immediate and long-term PTSD and lower probability of remission than refugees who had experienced few traumatic events (Kolassa et al., 2010). Suicide, which is often linked to PTSD, has also been found to be a greater risk for those who have experienced multiple severe disasters (Norris, Friedman, & Watson, 2002).

Individual circumstances also influence long-term rates of distress and anxiety. Many, perhaps even most, disaster survivors experience worry about future disasters, feelings of vulnerability, helplessness, mourning, grief, and despair (Neria & Schultz, 2012). For some, these concerns may be heightened by economic losses from missed workdays, use of medical services, recovery from injury, or other disaster-related exposure. Individuals who have greater resources to draw upon generally fare better in the long-term than those with less (Hobfoll, Stevens, & Zalta, 2015) In addition, personal emotional response can amplify stress. A study of Australian residents impacted by bush fires suggests that feelings of anger, directed both at the unfairness of the disaster itself as well as at authorities responsible for inadequate recovery programs, increased negative mental health outcomes, particularly for men (Forbes et al., 2015). Finally, it appears to be those most rooted in their communities who experience more pronounced psychological distress as a result of disaster-related changes to the landscape and community (Lyon et al., 2015; also see Lee and Blanchard, 2012). Specifically, strong attachments to, and identification with, one’s home and community increases the pain of seeing them irrevocably changed. Both during and after a natural disaster, the local environment can change abruptly. This, as found in a study of tornado survivors, may lead to high levels of emotional pain and disorientation, even for those who have not experienced other personal loss from the disaster (Silver & Grek-Martin, 2015). Furthermore, the sense of one’s home as a safe and secure environment may be devastated by an acute event (Tapsell & Tunstall, 2008), increasing the long-term emotional stress burden.

9.4 Mental health impacts from chronic climate changes

Most accounts of climate change focus upon the tangible and acute events associated with it—heat waves, coastal flooding, extreme storms, or the sudden collapse of an ice shelf—and often overlook its chronic, slowly building impacts. Although it is critical to understand the dangers of clear and identifiable acute events, an exclusive focus on them occludes the more gradual and less dramatic impacts of climate change that ultimately will affect a much larger number of people on a daily basis. The chronic effects of a changing climate not only tend to be slow-growing and often diffuse but also widespread and persistent. For example, plants and animals are gradually disappearing from areas they have inhabited for thousands of years, and the timing of events such as animal migrations and plant flowerings are shifting (Root et al., 2003). The destruction caused by chronic climate change impacts may initially seem insignificant, but, as time passes, the cumulative effects have the potential to be destructive to both ecological systems and human communities.

Some of the specific threats posed by gradual changes in climate are increased temperatures, drought, migration, and more abstract changes associated with loss and worry. Climate change is likely to bring other changes as well, such as repeated minor (“nuisance”) flooding or changing patterns of recreation, whose impacts on wellbeing are mostly still unknown (e.g., Dahl, Fitzpatrick, & Spanger-Siegried, 2017; Upton, 2017).

9.5 Impacts of climate change on social relationships

The possible impacts of both acute and chronic aspects of climate change on social relationships are underresearched and not well understood, but likely to be significant. Natural disasters, for example, have the potential to impair critical connections to family members. When homes are severely damaged or destroyed by a flood, storm, or wildfire, families often need to be relocated, sometimes multiple times, before being reunited and settling permanently. The stress experienced through relocation is immense (Ursano, McCaughey, & Fullerton, 1995), and, because a person’s home provides an important context for social relationships (Carroll et al., 2009), the loss of a home may have significant negative influence on a family’s social dynamics. Indeed, researchers have documented higher rates of domestic abuse, including child abuse, among families who have experienced disasters (Fritze et al., 2008; Harville, Taylor, Tesfai, Xiong, & Buekens, 2011; Keenan, Marshall, Nocera, & Runyan, 2004; Yun, Lurie, & Hyde, 2010).

Postdisaster stressors appear to have a negative impact on less intimate social relationships and interactions as well (friends, coworkers, etc.; e.g., Palinkas, Downs, Petterson, & Russell, 1993; Simpson et al., 2011), perhaps in part because heightened anxiety and uncertainty about one’s own future can reduce the ability to focus on others. In addition, extreme weather events, which tend to hit an entire community, weaken the very social support networks that normally provide help to people when they are most in need (Aldrich & Meyer, 2014). For example, after Hurricane Katrina, the areas hardest hit were also the most likely to have lost the physical gathering place of the community, such as a community church, which had served as the center of social networking and support (Cherry, Marks, Adamek, & Lyon, 2015). This made it more difficult for the community to come to each other’s aid during the difficult disaster aftermath.

With respect to the chronic impacts of climate change, one of the social consequences most frequently mentioned is the potential for increased violence. The psychological impacts of warmer weather are fairly well understood based on decades of research on this topic. One paper synthesized the results of 60 quantitative studies examining the link between climate conditions and various types of violence, for example, domestic crime, murder, rape. This metaanalysis included both lab-based experiments and quasiexperiments in the field and found a causal relationship between heat and aggression: As the temperature goes up, so does interpersonal aggression (Hsiang, Burke, & Miguel, 2013) This has led researchers to predict that the increased average temperatures associated with climate change will cause a significant uptick in violence (Anderson, 2012), including violent crime, rape, and intergroup conflict (Carleton & Hsiang, 2016; Hsiang et al., 2013). In several recent analyses, Carleton and Hsiang (2016) and Hsiang et al. (2013) also found evidence that rising temperatures increased the frequency of interpersonal violence. Other researchers have presented both correlational and experimental data demonstrating that increased heat leads to a decrease in helping behavior (Belkin & Kouchaki, 2017).

Several other mechanisms in addition to heat and extreme rainfall contribute to a predicted rise in interpersonal conflict. First, violence and aggression may increase when competition for scarce natural resources increases, or when ecomigration brings formerly separate communities into contact and compete for resources like jobs and land. Second, as communities disperse and their social networks become disrupted, the restraints on crime that exist in dense and well-established social networks are no longer present, leading to higher probability of criminal behavior. This is worsened when government resources are diverted away from criminal justice systems, mental health agencies, and educational institutions, all of which tend to help mitigate crime (Agnew, 2012). Finally, climate change appears likely to increase economic pressures and uncertainty through, for example, labor productivity losses from heat stress; high demand for electricity that strains the electrical grid, particularly on hot days; lower agricultural yields from both high temperatures and extreme rainfall events; and fluctuations in local economic activity and demand as climate conditions change (Carleton & Hsiang, 2016). These unpredictable economic effects will likely raise the general level of frustration in society and consequently aggravate interpersonal aggression.

Recent research suggests that climate change not only leads to greater interpersonal conflict but it also exacerbates the potential for larger scale intergroup violence (e.g., Carleton & Hsiang, 2016; Hsiang et al., 2013), through, for example, economic hardship or intergroup competition for scarce resources. Indeed, the Department of Defense and the UN Security Council, among others, have recognized climate change as a “threat multiplier,” increasing the likelihood of intergroup conflict and for that reason threatening our national security. In addition to showing a link between climate changes such as rising temperatures and extreme rainfall, on the one hand, and interpersonal violence on the other, Hsiang et al. (2013) also found an association with intergroup conflict such as minority expulsion, civil conflict, political unrest, and social collapse. Climate change is likely to exacerbate many of the factors that inhibit community members from working together across social group boundaries, such as decreased social cohesion and connectedness and lack of trust between community members and for institutions (Norris, Stevens, Pfefferbaum, Wyche, & Pfefferbaum, 2008). For example, one study found that people who were thinking about climate change became more hostile to individuals outside of their social group (Fritsche, Cohrs, Kessler, & Bauer, 2012), which can be a precipitating factor for larger scale conflict.

9.6 Vulnerable populations

As Gifford and Gifford (2016) and others have stated, climate change is an issue of social justice. Although everyone will be affected by climate change, and the effects on everyone are of concern, it is important to recognize the disparities in the ways that effects are experienced. These disparities will tend to increase the overall level of inequity in society, increasing intergroup tensions and resentment. At greatest risk are those who have fewer economic or social resources to support them—individuals from poor and minority communities; those whose exposure is greater, such as first responders; and those who are for one reason or another are more susceptible. The elderly, for example, are often at greater threat from the physical effects of climate change, such as heat; research also suggests that they are more likely to develop mental health problems following natural disasters (Parker et al., 2016). People who are already suffering from mental illness are also more susceptible, due to the possibility that their treatment will be disrupted as well as to the fact that some psychoactive medicines induce a stronger physiological response to heat (Page, Hajat, Kovats, & Howard, 2012). Some communities will be more strongly affected by climate change by virtue of their geographical location. A thorough review of demographic differences in vulnerability to climate change can be found in Dodgen, Donato, and Kelly (2016).

At the community level, demographic factors linked to high sensitivity to climate impacts include high levels of poverty, lower education levels, and large populations of elderly, children and infants, disabled people, and recently arrived immigrants, migrants, or refugees, all of whom tend to require greater access to services that climate change impacts can put at risk (Weissbecker & Czinez, 2011). People in these groups tend to have fewer physical and emotional resources, and this in turn weakens the community’s ability to respond to all its members’ needs. Areas with high number of residents lacking access to health care or health insurance, or already experiencing poor health (Edwards & Wiseman, 2011), are especially likely to be negatively affected by climate change. Communities in which people’s livelihoods are directly tied to the natural environment, through agriculture, fishing, or tourism, are also at greater risk, and there are detailed reports of farmers in Australia who have been negatively affected by prolonged periods of drought (e.g., Alston, 2012; Hanigan, et al., 2012).

Some groups of particular concern because of their higher vulnerability to the many negative effects of climate change include women, children, low-income and racial minority groups, and indigenous communities.

9.7 Toward resilience

“Resilience” is the ability of a system to function in the face of adversity, to survive, and, perhaps, even to thrive (Hobfoll et al., 2015). The “system” could be an individual person, or a household, or even a community—resilience can be seen at many scales (Abramson et al., 2015; see Chapter 11: Psychological perspectives on community resilience and climate change: Insights, examples, and directions for future research). At the level of the individual person, resilience is the norm. People face many forms of adversity, and most come through it with positive adjustment and without psychopathology (Bonanno, 2008; Hanbury & Indart, 2013). Even so, much can be done to increase the resilience capacity of individuals and communities, particularly in response to climate change.

As stated earlier, health is more than the absence of disease or injury. Addressing climate change could improve health in ways beyond the mere avoidance of disaster. For example, many of the arguments for moving to clean energy emphasize the health improvements associated with a reduction in air pollution (e.g., Perera, 2017). Encouraging people to walk or ride their bikes rather than relying on automobiles for transportation will improve physical fitness and reduce obesity (Bain et al., 2016). Reducing the consumption of red meat could have a significant impact on both carbon emissions and cardiovascular health (Westhoek et al., 2014).

Protecting green spaces will not only provide ecosystem benefits through trees’ role in carbon capture but green spaces also provide access to the range of benefits that bring about human wellbeing. This is documented by a rapidly growing body of research (e.g., Bowler, Buyung-Ali, Knight, & Pullin, 2010; Carrus et al., 2015). Increasing evidence suggests that not only individual wellbeing but also community relationships may be positively affected by access to green space: natural spaces encourage social interactions and more positive attitudes toward others (e.g., Kuo & Sullivan, 2001; Weinstein et al., 2015). Weinstein et al. found that both objective amount of nature in a neighborhood and the amount of reported contact with nature were positively associated with social cohesion and negatively associated with crime, even after controlling for socioeconomic factors.

Following natural disasters, social capital may be one of the factors most strongly associated with resilience (Mathbor, 2007). Resilience research suggests the value of strong social networks in overcoming adversity, because connected communities possess the trust, cooperation, and communication that undergird any type of group effort (Aldrich & Meyer, 2014; Aldrich, 2012). Community social capital and trust has been linked to lower rates of crime and violence as well as higher participation in civic activities that benefit the entire community (Hirschfield & Bowers, 1997). Social cohesion also benefits individuals. Personal mental health is better in communities with stronger social fabric (Friedli, 2009); when social networks are dense and inclusive, they offer residents a wider array of meaningful social interactions. Social interactions are particularly important during difficult times (e.g., Terpstra, 2011), and people experience an extra boost in their own wellbeing through opportunities to help others in need.

As stated by Wolsko and Marino (2016), helping people to adapt to climate change requires attending to more than material needs. Enabling cultural continuity and the ability to connect to the natural world are also important. As emphasized by Doherty (this volume) and others (e.g., Clayton, Manning, & Hodge, 2014; Clayton, Manning, & Krygsman, 2017), greater resilience is also achieved through improved social equity. Reducing poverty, for example, reduces the number of individuals and communities that lack the resources they need to cope with climate change. Greater equity also contributes to stronger social cohesion within a community, which in turn expands the social networks that provide individuals with essential support during difficult times.

9.8 Conclusion

This chapter has described the many serious risks that climate change poses for human wellbeing. A substantial body of research has documented the impacts of natural disasters, which are projected to increase due to climate change, on mental health and community relations. The psychological impacts of more gradual changes in the climate have received less research attention, but as the studies reviewed here suggest, there is substantial reason for concern. Chronic climate impacts, such as drought, rising temperatures, and other slowly unfolding changes to the landscape, are a source of stress and are likely to increase individual distress as well as overall aggression and intergroup conflict. Climate change will also require changes in the ways in which people think about themselves, their culture, and their relationship to place, changes which will impact mental health in ways that are not fully clear.

Importantly, these impacts will be unevenly distributed. Physical, social, and/or geographic sources of vulnerability combine to determine different levels of risk. Children and the elderly are most physiologically susceptible. Women, indigenous groups, minority groups, and the poor are vulnerable due in part to their social positions and lack of access to power. People who live in geographically vulnerable areas, such as coastal areas, the Arctic, or areas subject to desertification, will see more dramatic impacts of climate change, but those with the economic resources will be able to protect themselves to some extent. The resulting inequities will likely contribute to social conflict.

Climate change is more than a series of negative consequences to be avoided. It is a challenge to our current way of life. As such, it is also an opportunity to reevaluate and recalibrate dysfunctional aspects of our society. The threat of climate change may be able to motivate changes in physical and social infrastructure that can provide cobenefits for physical and psychological health.

The impacts on individual and collective wellbeing make this a crucial area for psychological research. We highlight a few important research questions: