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Clinical Ecopsychology: The Mental Health Impacts and Underlying Pathways of the Climate and Environmental Crisis

REVIEW

published: 21 May 2021

doi: 10.3389/fpsyt.2021.675936

Clinical Ecopsychology: The Mental

Health Impacts and Underlying

Pathways of the Climate and

Environmental Crisis

Myriam V. Thoma 1,2*, Nicolas Rohleder 3 and Shauna L. Rohner 1,2

1 Psychopathology and Clinical Intervention, Institute of Psychology, University of Zürich, Zurich, Switzerland, 2 University

Research Priority Program “Dynamics of Healthy Aging,” University of Zürich, Zurich, Switzerland, 3 Friedrich-Alexander

University Erlangen-Nürnberg, Chair of Health Psychology, Erlangen, Germany

Edited by:

Wulf Rössler,

Charité – Universitätsmedizin

Berlin, Germany

Reviewed by:

Conrad Stanisław Zygmont,

Helderberg College, South Africa

Thomas Doherty,

Thomas Doherty, United States

*Correspondence:

Myriam V. Thoma

m.thoma@psychologie.uzh.ch

Specialty section:

This article was submitted to

Public Mental Health,

a section of the journal

Frontiers in Psychiatry

Received: 12 March 2021

Accepted: 26 April 2021

Published: 21 May 2021

Citation:

Thoma MV, Rohleder N and

Rohner SL (2021) Clinical

Ecopsychology: The Mental Health

Impacts and Underlying Pathways of

the Climate and Environmental Crisis.

Front. Psychiatry 12:675936.

doi: 10.3389/fpsyt.2021.675936

Humankind is confronted with progressing climate change, pollution, environmental

degradation, and/or destruction of the air, soil, water, and ecosystems. The climate

and environmental crisis is probably one of the greatest challenges in the history of

humankind. It not only poses a serious current and continuing threat to physical health,

but is also an existing and growing hazard to the mental health of millions of people

worldwide. This synergy of literature provides a current summary of the adverse mental

health impacts of the climate and environmental crisis from the perspective of Clinical

Psychology. Furthermore, it presents potential underlying processes, including biological,

emotional, cognitive, behavioral, and social pathways. The existing data suggest that

the climate and environmental crisis not only acts as a direct stressor, but can also

exert a detrimental impact on the various pathways, with the potential to amplify an

individual’s biopsychosocial vulnerability to develop mental ill-health. This is a call for

an increased investigation into this emerging research ﬁeld of Clinical Ecopsychology by

clinical psychologists and other researchers.

Keywords: mental health, mental disorder (disease), climate change, vulnerability, resilience

INTRODUCTION

The human impact on the Earth has become so meaningful that the present geological epoch has

been termed the “Anthropocene”, i.e., a time of signiﬁcant human-created geological change (1).

This deﬁnition of the Anthropocene gives equal consideration to the potentially positive, as well as

negative, imprints of humankind on Earth. On a positive note, the progressively globalized social

system, a core attribute of the Anthropocene (2), has led to the unprecedented opportunity to share

and grow knowledge across the globe, to promote social connections, and to allow an unparalleled

global mobility. On a negative note, the rapidly growing human population has had a large-

scale impact on the Earth in the form of an unprecedented pollution, environmental degradation,

destruction of the air, soil, water, and ecosystems, as well as the mass destruction of species across

the globe. The human imprint has triggered climate and environmental changes that have the

potential to endanger the survival of the human race. In fact, the growing existential threat posed

by this anthropogenic climate change has led 11,258 scientists from over 150 countries to come

together to warn people about the climate emergency (3). The anthropogenic climate change is not

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Mental Health in Climate Crisis

FIGURE 1 | Placement of the research ﬁeld “Clinical Ecopsychology” between

“Clinical Psychology” and “Ecopsychology”.

only regarded as “. . . potentially the biggest global health threat in

the twenty-ﬁrst century” [(4), p. 1,693], but is arguably one of the

most important challenges in the history of humankind.

This human-driven climate and environmental crisis can both

directly and indirectly inﬂuence health and well-being. While

the focus of prior research was directed toward physical health,

comparatively little research exists on the mental health impacts.

However, the investigation of the mental (ill-)health implications

of the progressing climate change, pollution, environmental

degradation, and/or destruction of the air, soil, water, and

ecosystems is a rapidly expanding research ﬁeld (5–9). The

growing interest in this area can be demonstrated by the number

of publications on the topic “climate change and mental health”

in PubMed, which sharply increased in 2020 with 120 new

publications, compared to just 69 in 2019. This research area

warrants particular consideration, given the evolving urgency of

the climate and environmental crisis, combined with the growing

body of evidence of a substantial impact by the ongoing crisis

on mental health, and paired with the exponentially growing

number of publications on the topic. Special attention can be

focused on evolving phenomena such as this by the provision of

a distinct and precisely deﬁned area within which to capture such

research. As such, we herewith propose “Clinical Ecopsychology”

as an umbrella term for existing and future research eﬀorts that

are dedicated to fostering the understanding of the development

of mental ill-health in response to the climate and environmental

crisis. Given that Clinical Ecopsychology may be best described

as being an overlapping ﬁeld of “Clinical Psychology” and

“Ecopsychology” (see Figure 1), both research ﬁelds will be

described in more detail in the following sections. As this work

is written from the perspective of Clinical Psychology, a stronger

focus is placed on this particular ﬁeld.

Clinical Psychology

Clinical Psychology is a discipline that is involved in the

research, assessment, diagnosis, and treatment of mental ill-

health [e.g., (10)]. At the core of Clinical Psychology lies

the motivation to understand the complex nature of the

etiology of mental ill-health, as well as the determination to

optimally diagnose psychopathology. The overarching aim is

to develop new, further improve existing, and supply eﬃcient

and evidence-based treatment options. The Diagnostic and

Statistical Manual of Mental Disorders, in its ﬁfth edition [DSM-

5, (11)], as well as the 10th (and soon 11th) Revision of the

International Statistical Classiﬁcation of Diseases and Related

Health Problems [ICD-10, (12)], assist clinical psychologists and

others in the diagnosis of mental health disorders for research

and practice. Clinical Psychology can thus oﬀer the expertise

and knowhow to investigate, assess, describe, and diagnose

potentially psychopathological responses to the current climate

and environmental crisis. To better understand the impact of

the climate and environmental crisis on mental health, we can

therefore draw from models in Clinical Psychology.

A central model in Clinical Psychology is the vulnerability-

stress model (13, 14), according to which mental health disorders

develop as a result of an interaction between the presence

of stress and an individual’s vulnerability (or sensitivity) to

stress. This vulnerability results from the interplay of biological,

psychological, and social dimensions. The biological dimension

encompasses aspects related to physical health and physiological

functioning, including genetic, hormonal, and immunological

makeup; but also (mal)nutrition, (non-)communicable diseases,

and injuries. The psychological dimension includes emotional,

cognitive, and behavioral aspects, such as dysfunctional emotion

regulation strategies or negative cognitive schemata. The social

dimension includes aspects such as interpersonal conﬂicts

or loneliness. Depending on the interplay of these factors,

vulnerability is formed that renders an individual more or less

susceptible to stress and the subsequent development of mental

ill-health (13, 14).

Existing ﬁndings on the mental health implications of various

climate and environmental stressors support the notion that

these stressors can exert a meaningful impact on mental health

via biological, psychological, and social pathways. Furthermore,

these pathways do not act in isolation, but rather interact with

each other, as can be shown in a study with Inuit in Canada (15):

It was found that climate change-related alterations to the natural

environment (e.g., ice instability) profoundly interfered with

their traditional, land-based lifestyle, i.e., how they work, travel,

and gather food (behavioral pathway). This in turn negatively

aﬀected diet and activity patterns (biological pathway), cultural

identity, connection to the land, sense of place, and self-worth

(cognitive pathway). This was further linked to despair, sadness,

or hopelessness (emotional pathway); and can also impact social

behavior (social pathway) [see also (16)]. The Inuit situation

is a very good living example, which impressively shows the

diversity of the impact of a changing natural environment,

and the interwovenness of the underlying pathways. Through

the application of the vulnerability-stress model (13, 14), this

example demonstrates how Clinical Psychology can oﬀer a useful

explanatory model that can be applied in the understanding of

the development of mental ill-health in response to the current

climate and environmental crisis.

Current directions in Clinical Psychology include, but are not

limited to, the combination of clinical psychological research

with collected knowledge from clinical experience and practice,

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Mental Health in Climate Crisis

the development of evidence-based treatment guidelines, cross-

cultural considerations in the diagnosis of psychopathology

and culturally responsive care, the facilitation of low-threshold

accesses for the treatment of mental health problems (e.g., using

e-mental health interventions), the increased attention to (the

treatment of) mental (ill-)health in adults of advanced age, and

the adopting of a multisystem perspective on resilience [e.g., (17–

19)]. These current directions in Clinical Psychology align with

the demands posed by the climate and environmental crisis. It

is therefore important not to miss the opportunity to apply the

expertise of the large and inﬂuential ﬁeld of Clinical Psychology

to the current and constantly evolving climate and environmental

crisis. In fact, the ﬁeld of Clinical Psychology is becoming

increasingly aware of the mental health impacts of the crisis [e.g.,

(20)]. For example, this increasing awareness was reﬂected in

the organization of the ﬁrst International Summit on Psychology

and Global Health in 2019, held in Portugal, which was attended

by leaders of multiple psychological associations from over 40

nations (21). At this gathering, the leaders declared an agreement

to employ psychological research to ﬁght climate change.

However, despite the readiness of Clinical Psychology to

address the climate and environmental crisis, certain barriers

exist that may also hinder an in-depth dedication to this emerging

research ﬁeld. Such barriers include, but are not limited to: (a) the

vast complexity of the anthropogenic climate and environmental

crisis, and the resulting diﬃculty to attribute a causal link

between the climate and environmental crisis and mental ill-

health (22); (b) the multiple possible direct and indirect impacts

on various biopsychosocial life-domains, which are challenging

to assess; (c) the general complexity of the etiology of mental

health disorders; (d) the potential personal reluctance to deal

with this topic due to a lack of knowledge (e.g., regarding the

human-nature relationship), personal fears, or potential denial

of the climate and environmental crisis; and ﬁnally, (e) clinical

psychologists working in research or clinical practice may have to

focus on more immediate or urgent priorities. For instance, while

the Covid-19 crisis has shed light on the importance of mental

health [e.g., (23)], it has also undeniably upstaged the ongoing

climate and environmental crisis. Targeting such barriers can

help facilitate the eﬀective integration of Clinical Psychology in

addressing the climate and environmental crisis.

Ecopsychology

Ecopsychology has “. . . a healthy diversity in conceptions” [see for

instance, (24), p. 2], which can make it diﬃcult to provide an all-

encompassing, commonly-accepted deﬁnition of Ecopsychology.

Broadly, Ecopsychology can be described as the research ﬁeld

dedicated to the study of the connection between human-caused

changes to and destruction of the natural world “. . . and the

spiritual or psychological crises resulting from our increasing

experience of separation from the more-than-human world.

Ecopsychology looks for the roots of environmental problems in

human psychology and society and for the roots of some personal

and social problems in our dysfunctional relationship to the

natural world.” [(25), p. 68]. “Ecopsychology explores humans’

psychological interdependence with the rest of nature and the

implications for identity, health and well-being. Ecopsychology

topics include emotional responses to nature; the impacts of

environmental issues such as natural disasters and global climate

change; and the transpersonal dimensions of environmental

identity and concern” [(26), Ecopsychology section, para. 1].

Ecopsychology is one of six core sub-ﬁelds of Environmental

Psychology, in addition to “Behavior and the Built Environment,”

“Conservation Psychology,” “Psychology on the Population

Level,” “Teaching Psychology for Sustainability,” and “Using

Film to Demonstrate Environment and Behavior” [(27), Interest

Areas section]. According to Scull (25), in addition to

its connection to Environmental Psychology, the ﬁeld of

Ecopsychology is related to several other larger ﬁelds, such

as Psychotherapy, Spirituality, and Philosophy. Ecopsychology

itself is comprised of multiple sub-disciplines, which include

(but are not restricted to) sub-categories, such as Nature,

Spirituality, Transpersonal Psychology, Environmental Activism,

Experiential Environmental Education, Human Ecology, and

Ecotherapy and Nature Connection (25). As such, Ecopsychology

can be understood as a multi-faceted ﬁeld comprised of

numerous sub-disciplines that are all dedicated to the various

aspects of the human-nature interrelationship.

The therapeutic focus of Ecopsychology has been explicitly

stated (24), and is a core component of this ﬁeld [e.g., (28)]. This

relates to the assumption of Ecopsychology that human beings

are closely attached to nature. This close emotional and spiritual

bond and connection to nature is proposed to be due to the

phylogenetic development of the modern human, which lasted

hundreds of thousands of years and involved surviving in close

interconnection with the natural world [e.g., (29, 30)]. Given this

evolutionary “up-bringing” in nature, living in equilibrium with

nature is thought to be a crucial prerequisite for humans’ physical

and mental health and well-being (31). While Ecopsychology and

Clinical Psychology both have their place in understanding the

mental health impacts of the climate and environmental crisis, a

distinct research area drawing on the most relevant elements of

each ﬁeld can help advance this research topic further.

Clinical Ecopsychology

Clinical Ecopsychology seeks to systematically examine the

direct and indirect mental health impacts of the progressing

climate change, pollution, environmental degradation, and/or

destruction of the air, soil, water, and ecosystems. More

speciﬁcally, Clinical Ecopsychology sets out to examine

underlying pathways of how the climate and environmental

crisis can lead to the development of mental ill-health, which

entails the study of speciﬁc risk and vulnerability factors.

Clinical Ecopsychology also investigates potential protective and

resilience factors that may aid individuals in their adaptation

and that may foster the maintenance of mental health in the

face of the ongoing crisis. Clinical Ecopsychology further

aims to thoroughly examine the beneﬁcial mental-health

impact of contact with the natural world. Taken together,

Clinical Ecopsychology sets out to examine underlying

pathways that lead to the development of mental ill-health

in the face of ecological adversity. This involves the study

of risk, vulnerability, and protective factors to understand

interindividual diﬀerences in the response and adaptation to

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ecological adversity, and the promotion of (the creation of)

eﬃcient treatment options for mental health disorders linked to

the climate and environmental crisis.

It must be noted that Clinical Ecopsychology is not a new

research ﬁeld. Both Clinical Psychology, but in particular

Ecopsychology (in addition to Environmental and Conservation

Psychology), have previously made extremely valuable

contributions to the understanding of these topics [see for

instance (32–37)]. As such, Clinical Ecopsychology may also be

described as a respective sub-category of these ﬁelds: Clinical

Ecopsychology is a sub-ﬁeld of Clinical Psychology in its focus

on climate and environmental stressors and its consideration

of the beneﬁcial impact of nature/natural stimuli, which is an

existing, although still vastly neglected and marginal topic within

Clinical Psychology. Clinical Ecopsychology is equally a sub-ﬁeld

of Ecopsychology, as it shares many, though not all, interests of

Ecopsychology. For instance, Clinical Ecopsychology may not

(or only to a very limited extent) deal with topics such as Nature

Spirituality, Transpersonal Psychology, or Environmental

Activism, which are sub-disciplines of Ecopsychology (25).

Clinical Ecopsychology may also draw on more “clinical”

language than Ecopsychology, such as when describing

therapeutic processes and outcomes (e.g., to “treat” rather

than to “heal”). However, while Clinical Ecopsychology may

be most optimally placed between Clinical Psychology and

Ecopsychology (i.e., through their shared overlap), this should

not mask the fact that Clinical Ecopsychology is in itself a

multi-disciplinary research ﬁeld. In fact, an impressive and

rich variety of disciplines (e.g., Psychiatry, Psychology, Medical

Sciences, Sociology, Public Health, and Biology) have already

contributed to the increasing understanding of the mental health

impacts of the climate and environmental crisis. The multiple

disciplines from which it is possible to examine the mental-

health impact of the climate and environmental crisis mirrors the

multi-dimensionality of (the development of) mental ill-health.

As stated above, Clinical Ecopsychology not only focuses

on the development of mental ill-health in response to the

climate and environmental crisis; but also aims to foster a better

understanding of how mental health can be upheld in the face

of the ongoing crisis, and how mental health disorders linked

to ecological adversity can be most optimally treated. Potentially

useful therapeutic approaches include the validation and

management of emotional responses, verbalization of (complex)

emotions, fostering active hope, ﬁnding a balance between

pessimism and optimism, stimulating self-eﬃcacy, promoting

social connectedness, and training adaptive emotion regulation

strategies [e.g., (38)]. Cognitive strategies can also be used to

foster functional cognitive coping mechanisms, such as cognitive

reframing, problem solving, reﬂection of responsibility and own

contribution, putting negative thoughts into perspective, and

radical acceptance [e.g., (39, 40)]. Depending on the needs of

the individual, single or group settings should be oﬀered, and

low-threshold options should be made available, such as informal

meetings with like-minded individuals. These informal meetings

may be particularly important, as previous research has shown

that becoming active through collective group engagement is

linked to hope, a key protective factor in dealing with eco-anxiety:

“Hope can help them confront the problem and bear the burden

of taking on climate change without becoming overwhelmed”

[(41), p. 13]. Furthermore, given the positive impact of natural

stimuli, contact with nature and natural elements should be

integrated whenever possible into psychotherapeutic work on the

topics of Clinical Ecopsychology [for an overview see (42)]. For

instance, research on a form of nature therapy called Shinrin-

yoku, in which individuals spend time in the forest, has shown

reductions in mental fatigue through decreased prefrontal cortex

activity, reduced cortisol concentrations, and increased feelings

of comfort and calm (43). The deep-rooted psychophysiological

connection to nature may help individuals to (sub-)consciously

resonate with the natural environment and to respond positively

to its restorative inﬂuence (44–47).

In conclusion, it is the aim of Clinical Ecopsychology to

combine existing multi-disciplinary forces in order to create,

share, and promote the necessary knowledge required for: (a)

raising awareness of the increasing psychopathology stemming

from anxiety, frustration, and despair associated with the climate

and environmental crisis; (b) the maintenance of mental health

in the face of ecological adversity; (c) the eﬃcient treatment

of mental health disorders linked to ecological adversity; (d)

increasing access to mental health care across the globe,

particularly in those regions most aﬀected by the crisis; (e) the

planning and implementation of intervention measures; and (f)

the provision of additional research-based arguments for the

urgently needed global action on the current and worsening

climate and environmental crisis.

Aim and Structure of This Synergy of

Literature

Given the wide-ranging, and diverse multidisciplinary literature

on the mental health impact of the climate and environmental

crisis, a systematic literature search was not considered feasible

nor the goal of this report. Instead, this synergy of literature aims

to extend existing research by providing a current overview of

the core and most recent lines of research by summarizing the

existing literature from the perspective of Clinical Psychology.

The online databases PsychINFO, Web of Science, PubMed,

and Scopus were used for the literature search. Furthermore,

reference lists of appropriate articles were also screened for

additional studies. Search terms related to the following domains

were applied: mental health (e.g., mental health disorders,

psychopathology), climate change (e.g., climate crisis, global

warming), and environmental crisis (e.g., destruction of nature,

pollution). Only peer-reviewed articles written in English and

published by the end of September 2020 were considered for the

synergy of literature.

This article is structured as follows: climate and

environmental stressors are ﬁrst described, followed by an

in-depth examination of the mental health impacts of the various

ecological stressors. Potential underlying processes are then

summarized, encompassing biological and social pathways,

as well as the previously neglected emotional, cognitive,

and behavioral pathways. The way in which the climate and

environmental crisis can amplify an individual’s biopsychosocial

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vulnerability is then outlined. This is followed by a description of

risk and vulnerability factors, including vulnerable populations,

and the potential for increased adaptation to ecological stressors.

This synergy of literature concludes with a discussion of

methodological considerations and future directions.

CLIMATE AND ENVIRONMENTAL

STRESSORS

The climate and environmental stressors outlined in this report

refer to human-created ecological changes. “Human activities

are estimated to have caused ∼1.0◦C of global warming above

pre-industrial levels, with a likely range of 0.8–1.2◦C. Global

warming is likely to reach 1.5◦C between 2030 and 2052 if it

continues to increase at the current rate” [(48), p. 4]. The main

driving force behind the increasing temperatures is greenhouse

gas emissions, which are linked to economic growth, the steadily

growing human population, and the excessive consumption of

the wealthy lifestyle (3). Despite continuous warnings about the

state of climate change since the First World Climate Conference

in 1979, there is no evidence of a decrease in greenhouse gas

emissions (3). The consequences of this climate change are

manifold, including the loss of ecosystems and biodiversity, the

increase in ocean heat and acidity, the melting of the glaciers, the

rising sea level, as well as an increase in extreme weather events

and natural disasters (48).

In addition to climate change, humans are also responsible

for pollution of the air, soil, and water, as well as for the

destruction of biospheres and ecosystems, deforestation, and

resource extraction. Air pollution, largely caused by the burning

of fossil fuels (49), is a major concern in urban areas, particularly

in megacities and developing countries: “. . . 91% of the world’s

population lives in places where air quality levels exceed WHO

limits” [(50), Ambient Air Pollution section, para. 2]. Another

major form of pollution comes from mismanaged plastic waste,

which is detrimental for oceans and marine wildlife. It was

estimated that in 2010 alone, 4.8–12.7 million metric tons of

plastic waste entered the ocean (51). Pollution can also be

caused by oil spills, such as the Deepwater Horizon Oil Spill

in the Gulf of Mexico in 2010, with an estimated discharge

of around ﬁve million barrels of oil and natural gas. This oil

spill spoiled sediment, seawater, marine ﬂora and fauna, as

well as commercial seafood species, such as shrimp (52). The

unprecedented decline in nature in the history of human beings

(53) is so substantial that scientists describe the current loss of

biodiversity as the Earth’s sixth mass extinction (54). Across the

globe, scientists increasingly emphasize biodiversity issues, such

as the impact of the extinction of insect populations (55), the

need for conservation of subterranean ecosystems (56), or the

freshwater biodiversity crisis (57). Of particular concern is the

trend in deforestation, with a 49.6% increase per decade in global

tree cover loss over the last 20 years (3).

The eﬀect of this climate and environmental crisis can vary

depending on whether the phenomena are acute, sub-acute, or

chronic, and whether the eﬀect is experienced more directly

or indirectly. Acute events refer to fast-onset disasters, such as

extreme weather events or an oil spill. Sub-acute events refers

to slow-onset or slow-moving disasters, such as droughts or air

pollution. Chronic events refer to more subtle occurrences and

insidious changes, such as the rise of sea levels or the decreased

livability of habitats in certain regions (5, 9). Individuals

can be directly aﬀected by disasters via personal exposure,

such as through injury, physiological harm, traumatization,

but also by abrupt community losses (e.g., by wildﬁre). In

many cases, individuals are indirectly aﬀected through the

various impacts of the climate and environmental crisis on their

biopsychosocial life-domains. This includes indirect psychosocial

impacts triggered by changes to one’s socio-environment, such

as by damages to the infrastructure of one’s hometown by a

hurricane, or by experiencing economic hardship and potentially

forced migration caused by a climate-change related drought.

Another indirect impact relates to the experiencing entity,

i.e., the subjective, psychological impact of the climate and

environmental crisis. Strong emotional reactions such as fear,

sadness, hopelessness, or guilt can arise due to witnessing the

crisis from a distance, such as through learning or increased

virtual exposure, i.e., confrontation with media representations

about the climate and environmental crisis (5, 38, 58, 59). All of

these described direct and indirect impacts can co-exist, overlap,

and be nested within each other.

While accumulated research evidence has demonstrated

physical health eﬀects [e.g., (60)], the investigation of the mental

health impacts of climate and environmental stressors is a

comparatively recently emerging research area, which can be

considered within the frame of Clinical Ecopsychology.

IMPACT ON MENTAL HEALTH

This section provides a current overview of studies investigating

the mental health impact of a variety of climate and

environmental stressors.

Impact of Extreme Weather Events and

Natural Disasters

Extreme weather events (e.g., ﬂoods), and natural disasters (e.g.,

wildﬁres) have been previously linked to a broad range of adverse

mental health outcomes (22, 61–66). The most commonly

reported mental health disorders in the aftermath of extreme

weather events and natural disasters are posttraumatic stress

disorder (PTSD) and depression, as well as anxiety, suicide, and

substance abuse disorders (22, 67, 68).

Large diﬀerences in prevalence rates are found in studies on

the impact of extreme weather events and natural disasters on

mental health [i.e., PTSD, 0.7–52.6%, anxiety disorders, −0.4 to

84%, and depression, 0.9–81%, (65)]. This may be due to multiple

factors, such as diﬀerences in socio-demographics (e.g., age, sex),

disasters (e.g., type, severity), magnitude of exposure, or applied

methodological diﬀerences (e.g., study design, psychometric

instruments) (65). In particular, assessment time plays a critical

role, as psychopathological burden varies as a function of time

(8). Burden appears to be higher in the short-term, reaching the

highest levels within the 1st year post-disaster and attenuates

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thereafter, with variations in peak and trajectory depending

on severity of symptomatology (22, 69). Nevertheless, despite

these prevalence diﬀerences, PTSD is repeatedly observed to be

the most frequently examined mental health disorder following

extreme weather events and natural disasters (70). Given the

particular characteristics of these events, such as the suddenness,

the destructive potential, and likelihood for severe sequelae (e.g.,

injury, death); it is unsurprising that such ecological stressors can

trigger the development of stress-related mental health disorders.

There is a lack of longitudinal studies on PTSD following

extreme weather events and natural disasters, with some notable

exceptions. For instance, McLaughlin et al. (62) examined the

impact of Hurricane Katrina on PTSD over time. From the

aﬀected individuals, 17.1% were estimated to have PTSD at 7–

19 months (baseline) and 29.2% at 24–27 months (follow-up)

post-disaster. Around 40% with PTSD at baseline had recovered

by the follow-up. More than 40% with PTSD at follow-up

showed a delayed onset, i.e., onset later than 6 months after the

hurricane (62). It should be noted that this study did not obtain

pre-disaster data on psychological functioning, which prevented

statements about the change in mental health in response to

the disaster. However, a set of studies (63, 64, 66) was able to

longitudinally compare psychopathological burden from pre- to

post-Hurricane Katrina in a high-risk sample of low-income

parents. At around 11 months post-disaster, Rhodes et al. (66)

found that serious mental illnesses were twice as high post-

disaster (13.8%) compared to pre-disaster (6.9%), with almost

half the sample (47.7%) showing probable PTSD. Follow-ups

were conducted with the same sample at 5 years (63), and 12

years after the hurricane (64). Probable PTSD declined from

33 to 16.7%, suggesting a slow recovery over time. Similarly,

non-speciﬁc psychological distress also showed an elevation

from baseline (24.0%) to the ﬁrst follow-up (35.2%), with a

slow decline thereafter (second follow-up: 30.1%; third follow-

up: 28.5%), but remaining above baseline values (64). These

studies show that more than a decade after an “acute” natural

disaster, adverse mental health eﬀects can still be detected in

some survivors.

Impact of Increasing Temperatures and

Extreme Heat Event

Increasing temperatures are resulting in a higher frequency of

extreme heat events, such as heat waves (48). The occurrence

of these extreme heat events is a major public health problem

as they have been linked to a vast array of mental health

consequences, including aggressive and criminal behavior, wake

and sleep disorders (e.g., insomnia, obstructive sleep apnea),

depression, and suicide (71–73). For example, Burke et al. (74)

observed an increase in suicide rates in the US and Mexico

(0.7 and 2.1%, respectively) between 1990 and 2010, in response

to a 1◦C increase in average monthly temperature (74). In

addition, a recent study provided large-scale evidence for the

climate change—mental ill-health relationship, by combining

meteorological data (between 2002 and 2012) with mental health

data from almost two million US residents (75). Results showed

that worse mental health was related to short-term exposure to

extreme weather events, multiyear warming, and exposure to

tropical cyclones (75).

Increasing temperatures have also been linked to higher

admission rates to emergency departments and psychiatric

hospitals in individuals with pre-existing mental health

conditions. For example, in the study by Shiloh et al. (73),

a signiﬁcant association was found between the maximum

environmental temperature and psychiatric hospital admission

rates of patients with an acute psychotic exacerbation of

schizophrenia. This suggests that psychotic symptomatology,

such as hallucinations or delusions, can vary as a function of

(higher persistent) temperatures, with disturbed sleep as a result

of the higher temperatures potentially playing a role (73). These

studies show the adverse impact that “chronic” events (i.e., rising

temperature) can have on mental health.

Impact of Droughts

Related to the increasing temperatures, climate change can also

increase the likelihood of droughts and precipitation deﬁcits in

some world regions (48). Droughts have previously been linked

to an increase in general mental distress. For instance, a study

examined the mental health impact of a long-lasting drought

in Australia and found that in response to the 7-year drought,

distress increased in rural (but not urban) habitants by 6.22%

(76). Another Australian study including 8,000 individuals found

“. . . that if the population in rural and regional areas of Australia

were not exposed to drought the incidence of mental health

problems in these areas would be 10.5% lower” [(77), p. 187]. An

increase in suicide rates during drought periods has repeatedly

been reported, but with inconsistent ﬁndings across studies

[e.g., (71)]. This research demonstrates the adverse eﬀects of

“sub-acute” events on mental health.

Impact of Water and Food Insecurity

Rising temperatures that cause the retreat of glaciers, along with

climate-change related variations in precipitation patterns, are

leading to a reduction in fresh water resources and in agricultural

yield. These changes aﬀect the water and food security of millions

of people worldwide, particularly those heavily dependent on

rivers and precipitation (78). The impact of climate change

on water and food supplies is complex and co-inﬂuenced by

political, social, and environmental factors (79). Two-thirds of

the world population are confronted with severe water scarcity

for a minimum of 1 month per year (80); and up to 800 million

people are aﬀected by food insecurity (81). These high numbers

show that water and food insecurity are large-scale risk factors for

health and well-being [e.g., (82)].

Water scarcity has been linked to psychological distress,

suicidality, anxiety, hopelessness, and depression [for a review

see (83)]. Insecure or scarce access to water can induce worries

about material deprivation, shame and stigma for failing social

roles or norms (e.g., begging for water, unable to clean oneself),

as well as persistent concerns about threats to physical health,

such as contaminated water (83). Similarly, food insecurity, and

the resulting malnutrition, has not only been linked to physical

health conditions (e.g., anemia, adverse physical development),

but also mental ill-health (81). A recent systematic review and

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meta-analysis on food insecurity and mental health found an

increased risk for depression and stress (84). The association

between food insecurity and depression followed a dose-response

pattern, with more food insecurity associated with a higher risk

for depression, with a higher risk observed for men and older

adults (above 65 years) (84). These studies illustrate the negative

impact that “sub-acute” events (i.e., water and food insecurity)

can have on mental health.

Impact of Air Pollution

Several studies have examined the impact of air pollution on

mental health [for an overview see (85)]. Exposure to (ultra)ﬁne

particulate matter has been linked to depressive symptomatology

in both cross-sectional (86) and longitudinal (87) research. In

the exploratory longitudinal study by Roberts et al. (87), results

showed that exposure to concentrations of air pollution at 12

years of age was associated with the development of depressive

symptoms and a higher risk of being diagnosed with depression

by the age of 18 (87). A recent systematic review and meta-

analysis also revealed that ambient particulate matter (with

an aerodynamic diameter smaller than 2.5 µm) was strongly

associated with an elevated risk of depression and marginally

related to a higher risk of suicide (88). Findings further suggest an

accumulative detrimental impact over time, with longer exposure

to particulate matter associated with greater risk of depression

(88). Furthermore, studies on air pollution and suicide have

shown increases in the rate of suicides of 1–2% per day of

poor-quality air (71).

In addition, exposure to air pollution has also been linked to

cognitive impairment, as well as to diseases aﬀecting the central

nervous system (CNS), such as Alzheimer’s disease (88–90). For

example, a population-based cohort study in Canada found that

individuals living in proximity to major roadways with high

levels of air and noise pollution had a higher risk of developing

dementia (91). Up to 11% of the dementia incidence within the

11-year observation period could be attributed to the heavy traﬃc

exposure and the related air pollution (91). These studies show

the adverse impact that air pollution, a “sub-acute” event, can

have on psychological and cognitive health and well-being.

Impact of Profound Changes to the Natural

Environment

Profound changes to the natural environment and landscape,

either by human-created destruction (e.g., open mining),

destruction through natural forces (e.g., wildﬁre), or as a

consequence of climate change (e.g., melting glaciers), can

evoke grief, sadness, and feelings of loss in (place-based)

solace. These emotions have previously been examined under

the terms ecological grief (16) and solastalgia (92). Ecological

grief is deﬁned as “. . . the grief felt in relation to experienced

or anticipated ecological losses, including the loss of species,

ecosystems, and meaningful landscapes due to acute or chronic

environmental change” [(16), p. 275]. Similarly, solastalgia refers

to “. . . the pain or distress caused by the loss of, or inability to

derive solace connected to the negatively perceived state of one’s

home environment” [(92), p. 96]. Ecological grief and solastalgia

have been observed in various populations across the world, such

as in the form of undermined notions of place-based, cultural,

and self-identity; cumulative and chronic place-based distress;

ampliﬁed mental health stressors; and heightened perceived

risk of depression and suicide [e.g., (15, 93)]. In particular,

individuals who live in close connection with nature, such as

Indigenous people or farmers, have been found to be more

vulnerable to the development of ecological grief and solastalgia

(16, 92, 94). These studies highlight the adverse mental health

impact of “chronic” ecological events in the form of profound

environmental changes.

Impact of Increased Awareness

A recent survey of over 27,000 participants from 26 countries

revealed that climate change was perceived as a major

international threat for half of the participating nations (95). This

indicates an increase in the perception of the threat posed by

climate change: while a median of 56% reported climate change

to be a top threat in 2013, this number increased to 63% in

2017, and 67% in 2018 (95). This perceived threat illustrates an

indirect eﬀect of climate change on mental health. For instance,

a qualitative study with young urban children (10–12 years old)

found that 82% reported feelings of sadness, fear, and anger in

relation to environmental issues and 72% expressed pessimistic,

negative, or apocalyptic views about the future (96). Furthermore,

a poll conducted with 2,107 U.S. adults on the topic of climate

change found that 56% identiﬁed climate change to be the most

important problem of today’s society, with 68% reporting having

experienced at least a little eco-anxiety (97). Younger participants

(18–34 years) were more aﬀected, with almost half reporting

climate change-related stress to have an impact on their daily

lives (97).

Thus, far, vast diﬀerences exist in the deﬁnition of eco-anxiety,

or climate (change) anxiety [e.g., (39, 98–100)]. This may be due

to the fact that eco-anxiety can be understood quite diﬀerently

from the varied perspectives of the respective disciplines (e.g.,

Sociology, Philosophy, or Depth-Psychology). Nowadays, some

describe it as “. . . a speciﬁc form of anxiety relating to stress or

distress caused by environmental changes and our knowledge of

them” [(40), p. 1,233], while others use it to describe a range of

negative climate emotions [e.g., (94)]. From the perspective of

Clinical Psychology, eco-anxiety is understood as a syndrome,

i.e., a set of psychological symptoms related to the broader

spectrum of anxiety or fear that are triggered by (thoughts about)

the climate and environmental crisis, which can cause subjective

suﬀering and lead to functional impairments. The APA deﬁnes

eco-anxiety as “. . . any anxiety or worry about climate change and

its eﬀects” [(97), para. 6]. From a clinical perspective, a deﬁned

set of criteria/symptoms for eco-/climate (change) anxiety do

not yet exist. Instead, various symptoms have been linked to

this particular anxiety, such as fear, distress, worry, sadness,

or rumination (98). Currently, climate change anxiety can be

assessed with a recently developed and validated measure by

Clayton and Karazsia (99). It must be noted that responding to

this unprecedented climate and environmental crisis with intense

negative emotions is not a pathological reaction, but rather can

be regarded as a normative, adequate, and justiﬁable response to

a real existential threat [e.g., (16)]. However, if the eco-/climate

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(change) anxiety becomes maladaptive and so intense that it

signiﬁcantly impacts psychosocial functioning (i.e., interferes

with everyday life functioning, causes profound suﬀering, or is

perceived as uncontrollable), ecological syndromes such as eco-

anxiety may become a clinically relevant concern warranting

clinical attention (98).

Regarding this clinically relevant concern of the climate

and environmental crisis, it is correct to state that the current

diagnostic manuals, i.e., the DSM-5 (11), and the ICD-10 (12), do

not include disorders such as eco-anxiety, climate-change phobia,

prolonged eco-guilt disorder, or climate-change depression.

However, it is a common misconception that is not possible to

diagnose mental health disorders triggered by the climate and

environmental crisis. In fact, the stressors associated with this

crisis can theoretically cause a multitude of diﬀerent mental

health disorders, depending on the individual biopsychosocial-

vulnerability constellation of the aﬀected person (13, 14). For

instance, having constant worries about the state of the climate,

the continuing deforestation of rainforests, the bee mortality,

or the future perspectives of one’s oﬀspring, could provide the

basis for the development of a Generalized Anxiety Disorder

(DSM-5: 300.02; ICD-10: F41.1), if the symptomatology were to

cause meaningful distress or signiﬁcantly impact the psychosocial

functioning. Furthermore, Adjustment Disorder (DSM-5: 309.9;

ICD-10: F43.20) is deﬁned as “. . . a maladaptive reaction to

an identiﬁable psychosocial stressor or multiple stressors that

usually emerges within a month after the onset of the stressor”

[(101), p. S3]. This is a suitable and useful mental health diagnosis

that can be used to describe a symptomatology of distress

triggered by climate and environmental stressors. However,

even if individuals did not meet the diagnostic criteria for an

existing mental health disorder, the suﬀering caused by a sub-

clinical/threshold symptomatology can also diminish quality of

life and may warrant clinical attention.

Impact of a Lack of Greenness and

Contact With Nature

Further evidence of the indirect eﬀects of climate change on

mental health can be seen in the rapidly ongoing trend toward

urbanization, as more and more people lose contact with the

natural world. The current discrepancy between the modern

(urbanized) lifestyle and our psychophysiological development

is thought to impact mental health. For example, the increased

amygdala activity observed in city dwellers, compared to

country or small-town dwellers, may be an indicator of the

higher stress of city living (102). Furthermore, higher levels of

urbanization have also been linked to increased psychopathology,

such as psychosis and depression [e.g., (103)], and higher

suicide rates (104). In addition, a recent large-scale cohort

study investigated the relationship between environmental

greenness and schizophrenia, using data from almost 870,000

individuals over a 10 years period (105). Results found that

higher environmental greenness was associated with a lower

schizophrenia incidence, suggesting that a lack of greenness may

be one factor explaining why urban areas are linked to lower

mental health (105).

UNDERLYING PROCESSES

Climate and environmental stressors can exert an impact on

mental health through multiple pathways, ﬁve of which are

presented in the following section:

Biological Pathway

In the following two sub-sections, the various physical

health impacts are presented, followed by an in-depth

description of psycho-pathophysiological processes induced

by environmental toxins.

Impact on Physical Health

Given the intertwined relationship between physical and mental

health [e.g., (106)], bodily harm by injuries or exposure to

environmental toxins, as well as (infectious) illnesses, diseases,

or physiological health conditions caused by climate and

environmental stressors can increase the vulnerability for the

development of mental ill-health. The impact of climate change

on injury is not well-examined (107). However, existing data

supports the notion that there is a link between changes in

climate and the occurrence of injuries. Extreme weather events

and natural disasters can increase the risk of injury. For instance,

a systematic review on the impact of extreme weather events

in developing countries reported an increase in injuries of 0.3–

37.3% (65). Additionally, anomalously warmer temperatures,

such heat waves, have been linked to an increase in deaths

from unintentional injuries (e.g., falls) and intentional injuries

[e.g., suicide, assault; (108)]. Heat stress was also signiﬁcantly

associated with an increased risk for work-related injuries, such

as falls, stab-cut injuries, or road traﬃc injuries (109).

Heat waves have also been linked to a vast array of climate-

sensitive health outcomes, including communicable and non-

communicable diseases [e.g., (110, 111)]. The human body

tries to adapt to heat in a number of ways, such as by

down-regulating thyroid hormones, up-regulating blood levels

of noradrenaline and prolactin, and increasing heart rate [e.g.,

(112, 113)]. Such heat stress can cause heat strain, hyperthermia,

dehydration, heat-related exhaustion, heat syncope, heat cramps,

and heatstroke [e.g., (112, 114)]. While healthy individuals can

be aﬀected by heat-related illnesses [for a review see (115)];

being of higher age, taking certain medications, having a chronic

disease (e.g., cardiovascular diseases, obesity, and diabetes), and

having mental and neurological disorders (e.g., schizophrenia)

are known risk conditions for heat-related illnesses (116–118).

Air pollution, which is exacerbated by warmer temperatures,

is also a risk factor for a range of chronic diseases and medical

conditions. Globally, air pollution has been shown to contribute

to 29% of lung cancer deaths, 24% of stroke deaths, 25% of heart

disease deaths, and 43% of lung disease deaths (50). While the

impact of air pollutants has been extensively studied with respect

to respiratory and cardiovascular diseases, it has also been more

recently examined in connection to CNS related disorders, such

as Alzheimer’s and Parkinson’s diseases (119).

Extreme weather events, such as heavy rainfalls and ﬂoods,

can give rise to water-borne diseases, which are meaningful

contributors to the global burden of disease and mortality

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(120). Examples of water-borne or water-related diseases include

gastrointestinal diseases (e.g., diarrhea, cholera), typhoid fever,

viral hepatitis, or schistosomiasis (82, 120, 121). Such diseases are

caused and fostered by multiple factors, including contaminated

water, limited access to sanitation facilities, lack of knowledge

about hygiene practices, shortage of electricity or plumbing,

overcrowding, or malnutrition (79, 120, 121). These diseases are

a particular concern in developing countries, which, among other

risk factors that limit adaptive capability (e.g., poverty), have

a higher likelihood to be severely aﬀected by extreme weather

events (121).

Vector-borne diseases are illnesses transmitted through

the bite of vectors (e.g., mosquitos, ticks), whose presence

and abundance are climate sensitive (122, 123). These

diseases include West Nile Fever, Lyme borreliosis, tick-

borne encephalitis, lupus, malaria, and dengue fever; and

they have been linked to climate change-related alterations

in regional and local climatic and environmental conditions

(79, 122–124). The increase in vector-borne (and zoonotic)

diseases is a consequences of several (interacting) mechanisms,

including changes in the geographical distribution range and the

population density of hosts and vectors, and changes in infection

prevalence and pathogen load (development, reproduction, and

replication) (124).

Pathophysiological Processes Induced by

Environmental Toxins

Environmental toxins in the form of air pollution can be

translated into psychopathology via biological pathways, due

to their toxic eﬀect on the CNS (85, 89). In this pathway,

(long-term) exposure to environmental toxicants in the air [e.g.,

(ultra)ﬁne particulate matter, nitrogen oxides, and heavy metals]

has been linked to environmentally-induced oxidative stress,

neuroinﬂammation, damage to the cerebrovascular system, and

neurodegenerative pathology (88, 89, 91). Previous studies have

shown that components of air pollution particles can reach the

brain via diﬀerent routes. For example, particulate matter and

absorbed and soluble compounds can enter the brain directly,

with consequences including neuroinﬂammation, microglial

activation, and blood-brain barrier damage or dysfunction (89).

Furthermore, a more indirect route is peripheral inﬂammation,

which is disinhibited as a consequence of the peripheral presence

of pollutants. This can exert further negative eﬀects on the brain

by circulating inﬂammatory cytokines (125). Together, these

processes stimulate neuropathology and diseases of the CNS.

In addition, the disinhibition of peripheral inﬂammation can

have negative long-term eﬀects on somatic health. Inﬂammatory

mechanisms are directly, and often causally, involved in many

pathophysiological processes, such as atherosclerosis, insulin

resistance, and the development of malignancies (126). Through

these mechanisms, inﬂammation contributes to life-threatening

diseases, such as cardiovascular disease, type 2 diabetes, some

types of cancer, and sarcopenia [e.g., (127, 128)]; Inﬂammation

can also have adverse mental health eﬀects, including the

development of depressive symptoms, fatigue, and long-term

cognitive decline (125, 129).

Emotional Pathway

The (topic of) climate change, pollution, and the destruction of

the natural environment can impact mental health by evoking

intensely negative emotions (98). This potential to induce

negative emotional responses is detailed in the following sections,

followed by a description of an underlying process through

which triggered emotional responses can detrimentally impact

mental health.

An Emotional Topic

The climate and environmental crisis can be understood as

a severe, and rather unique current (global) stressor, which

is associated with particular aspects that evoke or intensify

negative emotional responses. The fact that the existence of

humankind may be threatened by the consequences of this

crisis links it to themes such as existential threat, destruction,

or death [e.g., (39)]. These morbid associations can induce

mortality awareness, which “. . . creates an existential terror”

that can engage psychological defenses and provoke profoundly

distressing emotional reactions [(130), p. 3]. The global scale of

the crisis can further give rise to feelings of apathy, numbness,

loss of control, powerlessness, uncertainties about the future, as

well as a state of “eco-paralysis,” particularly in young people

(41, 94). These feelings can be further exacerbated by observing

the apparent inaction by global leaders and the general public to

mitigate or adequately address the crisis. In addition, the impact

of the climate and environmental crisis is unequally distributed

across the globe, often most aﬀecting those who contributed least

(131, 132). This issue of injustice is a component of the crisis that

has the potential to induce strong emotional reactions, including

anger, and (ecological) guilt (133).

Furthermore, human-created/technological disasters and

interpersonal traumatic experiences have commonly been linked

to worse mental health outcomes in comparison to natural

disasters, such as volcanic eruptions [e.g., (70)]. However,

extreme weather events are more common and intense due to

the magnitude of the anthropogenic climate change. This adds a

human-created component to these events and blurs the division

between natural and human-created disasters (58). The growing

awareness of the anthropogenic aspect to climate change and

related consequences, as well as the obvious human-created

elements of pollution and the destruction of the environment,

may have negative eﬀects on mental health (59).

Lastly, the natural world bears an emotional importance for

human beings (45). According to Wilson’s Biophilia Hypothesis

(134), humans have an inherent emotional aﬃliation to the

natural world, and “. . . an innate tendency to focus on life

and lifelike processes” [(30), p. 1]. Individuals living in close

connection to the natural world can experience this bond to

nature as similar to that with a person. For example, in interview

research with Inuit in Canada, one participant reported that

“. . . nature’s about, to us is like in a way, another person” [(135),

p. 19]. Observing the pollution and destruction of the natural

world can thus psychologically hurt individuals, induce feelings

of distress, and trigger emotional misery, particularly in those

with close bonds to nature.

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From Negative Emotions and Distress to Ill-Health

Longer-term experiences of stress, anxiety, or depression are

associated with altered basal activity of the main stress systems:

the sympathetic nervous system (SNS) and the hypothalamus-

pituitary-adrenal axis (HPA axis). The SNS tends to be over-

activated in individuals experiencing chronic stress, anxiety, or

depression, which is reﬂected by higher plasma concentrations of

epinephrine and norepinephrine, and is typically associated with

increased blood pressure, heart rate, and other sympathetically

controlled functions (136). The HPA axis mainly shows

alterations in its diurnal rhythm in response to stress, with the

speciﬁc changes depending on the duration and type of stressor.

For instance, for chronic stressors with a duration of several

months, the majority of studies report a ﬂattened diurnal activity

rhythm and markedly lower plasma cortisol concentrations, a

state called hypocortisolism (137, 138). Alterations in these two

stress systems converge in their eﬀect on dependent systems to

become a threat to health. One important dependent system

is the inﬂammatory system, which can be regulated by stress

systems, with the SNS typically exerting a stimulating eﬀect

on inﬂammatory mechanisms and the HPA axis exerting anti-

inﬂammatory eﬀects [for example see (139)]. Such stress-related

alterations (i.e., over-active SNS, under-active HPA axis), result

in over-stimulation or disinhibition of inﬂammatory pathways

and have typically been found in states of anxiety, depression, and

stress (140, 141).

Through the pathway of inﬂammation, psychological and

environmental eﬀects can converge to negatively aﬀect mental

and physical health (142). In the context of climate change,

psychological and environmental eﬀects can negatively aﬀect

brain and periphery, not only in an additive, but also in

a mutually potentiating way. For example, pollutant-induced

weakening of the blood-brain barrier (89) would make it

signiﬁcantly easier for inﬂammatory cytokines—which can

be the result of pollutants and/or psychological stress—

to enter the brain. This can potentiate immune-to-brain

signaling and thereby increase the development of further

sickness-related psychological symptoms. A vicious cycle can

develop, particularly in some vulnerable populations, with severe

consequences for mental and physical health [see (142)].

Cognitive Pathway

Climate and environmental stressors can impact mental health

through their potential to inﬂuence key self-concepts and to

induce non-adaptive cognitive defense mechanisms and coping

strategies. These components of the cognitive pathway are

detailed in the following sections.

Feelings of Identity

Humans can establish emotional bonds with their local

environment. People-place bonds serve a functional purpose in

the fulﬁllment of needs linked to solace, security, belonging,

self-esteem, and identity (93). These people-place bonds and

associated needs are threatened due to acute changes in the

environment by natural disasters, or gradual changes that are

either human-created or a consequence of climate change. This

particularly aﬀects individuals that live in close connection to

the natural world, such as Indigenous populations, or those

whose work and livelihoods largely depend on farmland (93). For

instance, the Inuit of Northern Canada have a close connection

to the land, and the changing environment has impacted their

traditional way of living and induced profound changes in how

they see and understand themselves. For example, in interviews

they reported that “. . . it’s who they are, it’s what they’ve been

grown up doing. And their parents have been doing it forever,

so I mean they’re kind of losing a sense of who they are” [(135),

p. 20]; or that “. . . Inuit are people of the sea ice. If there is no

more sea ice, how can we be people of the sea ice?” [Attutauniujut

Nunami/Lament for the Land; www.lamentfortheland.ca; found

in (16), p. 277]. This profound impact on the land, their way of

living, and their perceived identity can elicit feelings of despair

and even foster mental health issues. For example, research by

Kumar and Tjepkema (143) found that the suicide rate was nine

times higher for Inuit (72.3 suicides per 100,000 person-years at

risk) than for non-Indigenous people (8.0 suicides per 100,000

person-years at risk). The Inuit, who have close connections to

the land, are confronted by multiple stressors, among which is

the climate and environmental crisis.

Cognitive Defense Mechanisms and Coping

Strategies

Defense mechanisms and coping strategies, such as emotional-,

cognitive-, or meaning-focused coping, positive reappraisal,

or trust, can help individuals to deal with the unpleasant,

undesirable, or unacceptable emotional states and thoughts

elicited by the climate and environmental crisis. These

mechanisms and strategies can also assist in creating feelings

of constructive, active hope, as well as empowerment (39, 41).

However, despite the known dangers of the climate and

environmental crisis, resistance still exists against urgently

needed mitigation activities. Explanations for this include the

complex and abstract nature of climate change that is diﬃcult

to understand, visualize, and communicate; issues dealing with

uncertainties; temporal discounting (i.e., placing a diﬀerent value

on short-term vs. long-term rewards); group dynamic processes

(e.g., collective ignorance); or lack of personal relevance resulting

in lack of urgency to act [e.g., (7)]. This is described in the

Giddens Paradox: “It states that, since the dangers posed by

global warming aren’t tangible, immediate or visible in the course

of day-to-day life—however awesome they may appear—many

will sit on their hands and do nothing concrete about them. Yet

waiting until they become visible and acute before being stirred

to serious action will, by deﬁnition, be too late” [(144), p. 2].

Denial of the reality of climate change is a frequently observed

cognitive response, particularly in conservative white males,

conservative think tanks, or religious individuals (145, 146).

This denial can be evoked for various reasons, including by

mortality awareness, cognitive dissonance, protection of self-

and group-identity and social norms, or system justiﬁcation

(145, 147, 148). The Terror Management Theory [TMT, (149)]

oﬀers one explanation for why the climate and environmental

crisis can lead to strong denial responses in some individuals. The

TMT states that the cognitive ability of self-awareness is coupled

with the awareness of one’s own mortality (130). Cognitive

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defense mechanisms can be engaged to deal with the thoughts

of mortality elicited by the climate and environmental crisis:

“. . . accessible death thoughts activate proximal defenses, for

example, suppressing death-related thoughts via distraction or

rationalization, or pushing the problem of death into the distant

future and denying one’s vulnerability. Cognitively inaccessible

death thoughts activate distal defenses, for example, maintaining

self-esteem and faith in one’s cultural worldview” [(130), p. 3, 4].

Denial can also be a consequence of cognitive dissonance

(147). Knowing that immediate global action is required calls for

behavioral changes, which can be daunting and also hindered by

various barriers, such as unwillingness to give up a comfortable

lifestyle (41, 147). The conﬂict between being informed about the

crisis and being unwilling or unable to take mitigating actions

can create cognitive dissonance, which can be solved using denial

mechanisms, such as rejection of blame or responsibility, or

condemning the accuser (147). Furthermore, denial on a political

level (by politicians) can provide false hope that there is no

problem or threat, which can reinforce the belief that there is

no reason for negative feelings [see (39)]. The complex and

abstract nature of climate change, coupled with cognitive coping

strategies can help explain the observed inaction toward the

climate and environmental crisis.

Behavioral Pathway

Climate and environmental stressors can also impact mental

health via health-related behaviors. Health-damaging behaviors

are often maladaptive responses to facilitate coping with

(overwhelming) negative emotions and aﬀective states (e.g.,

anger, fear), or unfavorable or harmful circumstances and

environments [e.g., (150)]. An example of one health-damaging

behavior is lack of physical activity, which has been associated

with food insecurity (84), air pollution (86), and lower exposure

to greenspace (151). In contrast, being surrounded by greenness

has been shown to foster physical activity, which may positively

impact weight and health [e.g., (152, 153)]. Surrounding

greenspace has also been found to facilitate social cohesion (154).

Both (outdoor) physical activities and positive social interactions

and social cohesion have repeatedly been linked to beneﬁcial

impacts on mental health [e.g., (155–158)].

Another health-related behavior that is aﬀected by climate

change is sleep behavior (i.e., sleep time and quality), which

can be impacted by heat (72, 159). Given the importance of a

healthy sleep pattern for good mental health [e.g., (160)], this

is an important pathway to consider in the understanding of

how an ecological stressor (i.e., heat) can translate into poorer

mental health.

Criminal activity and violence is a further set of behaviors

that has previously been linked to changes and shifts in climate

and weather and that has potential to aﬀect physical and mental

health. A study conducted in California that investigated the

impact of drought on state-level rates of crime over an extended

period of time found a meaningful increase in property (but not

violent) crimes (161). A recently published study that analyzed

survey data encompassing information from 80,000 women

living in sub-Saharan Africa found that drought was linked to

intimate partner violence, particularly in female adolescents and

jobless women (162).

Social Pathway

Given the impact of the climate and environmental crisis

on multiple aspects of social life and socio-economic factors,

combined with the fact that social determinants are meaningfully

related to mental health (163), the social pathway is a key

translator of climate and environmental stressors into mental

health eﬀects [e.g., (5)].

Destabilization of Social Relationships and Social

Networks

Humankind is a social species and positive social interactions and

social support are crucial for mental health, as they constitute

important protective forces against the development of various

mental health disorders, particularly PTSD (164). Climate and

environmental stressors can destabilize social networks, interrupt

social support chains, and reduce social cohesion. For example,

food insecurity has been shown to lead to hopelessness and low

levels of self-eﬃcacy, which destabilized social relationships and

increased the risk for depression (84). Furthermore, changes

in urban social behavior have been observed as a result of

air pollution, such as interacting less with neighbors (i.e.,

lower “social reciprocity”), which has been linked to depressive

symptomatology (86). These studies illustrate the detrimental

eﬀect of the climate and environmental crisis on both social and

mental health.

Impact on Socio-Economic Factors

Climate change, pollution, and destruction of the environment

can impair an individuals’ socio-economic status, and ultimately

their mental health, by interrupting salary payments or

education, loss of employment, ﬁnancial constraints due to

reduced agricultural production, crop failure, loss of livelihoods,

or migration (131). For example, long-lasting heat waves and

droughts have been shown to inﬂuence socio-economic hardship

through the impact on work capacity, labor productivity,

livelihoods, agricultural production, and food and water security

(165). The complexity of this pathway is illustrated in a systematic

review by Vins et al. (166) on the long-term mental health

impact of drought. Drawing on data from 82 articles, the

authors created a causal process diagram depicting the multiple

indirect and interacting pathways between droughts and mental

health. Drought was found to have multiple economic impacts,

particularly for those dependent on weather conditions for their

livelihood (e.g., farmers), which can result in ﬁnancial hardship

and endanger food security. This in turn can lead to stress, social

isolation, interruption of education, worries about the future,

denial, intimate partner violence, substance abuse, feelings of

shame, depression, or suicide. This impact of drought (and the

related economic eﬀects) on mental health was shown to have a

dose-response relationship, i.e., the more severe the drought, the

worse the psychopathological consequences (166).

In connection to the economic eﬀects, drought-related

migration was further identiﬁed as having an important inﬂuence

on mental health. The large-scale migration, resettlement,

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and displacement of people and populations are and will

become necessary in response to the unfolding climate and

environmental crisis, as a result of depressed economies and

decreased environmental resources, such as food or water (166).

This has the potential for a multitude of problematic social

consequences, including disrupted social networks, loss of (land-

bound) cultural traditions, acculturation stress, social turmoil,

civil and international conﬂicts, and even wars (166–168).

Regions of the world that struggle with corrupt political systems

and social inequality are at higher risk of being aﬀected by these

developments (38). This research highlights the far-reaching

socio-economic and related psychosocial health impacts of the

climate and environmental crisis.

VULNERABILITY AND ADAPTATION

If the current rate of climate and environmental change is

maintained, an overall increase in the adverse mental health

impacts can be expected. However, individuals diﬀer with respect

to their vulnerability to ecological stressors, with the highest

levels of vulnerability seen in those with pre-existing conditions

(e.g., physical illnesses), higher exposure to ecological stressors,

and reduced access to resources [e.g., (61, 113, 158)]. The

following sections will describe risk and vulnerability factors,

including vulnerable populations, as well as factors with the

potential for increased adaptation in the face of climate and

environmental stressors.

Vulnerability

The climate and environmental crisis further increases existing

inequalities by disproportionally aﬀecting marginalized

groups that are inherently vulnerable, for example, due to

their development status (e.g., children), socio-economic

disadvantage, or having mental health issues [e.g., (8)]. Such

vulnerabilities do not act in isolation, but rather interact with

each other. For instance, Indigenous people often live in

geographical regions prone to extreme weather events, and

typically have lower socio-economic resources and social power

(7). Such economic, social, and gender inequalities are also risk

factors for the development of psychopathology, and the added

impact of climate and environmental stressors can lead to worse

mental health (38, 132, 163).

Risk by Exposure

A diﬀerential impact on mental health is expected as a function

of the magnitude of exposure to ecological stressors, with greater

(peri- and post-) disaster exposure resulting in more adverse

mental health eﬀects (66, 67, 84, 169). For instance, high

disaster exposure (as assessed by magnitude of disaster, property

loss, witnessing someone dying, risk of own death, casualties,

physical injuries, food/clothing insecurity, violence, or practical

problems) has been shown to be a relevant risk factor for the

development of (probable) PTSD (65, 70, 170, 171).

Exposure to the climate and environmental crisis is unequally

distributed across the globe as a function of geographical

regions that are more or less prone and sensitive to ecological

stressors. More susceptible populations include those living in

and dependent on rural landscapes (e.g., farming populations), in

regions of dryland, in areas prone to ﬂoods, and in remote areas

(48, 76). This vulnerability can be due to the geographical and

social isolation, reduced infrastructure, lower levels of economic

resources, or transport options (172). Developing countries,

and particularly regions of the Global South, are also more

vulnerable as they are more aﬀected by water insecurity, steadily

growing populations, increasing urbanization, and ever-present

poverty (82, 120, 121, 132). Populations in urban regions are

also exposed to ecological stressors, with a higher exposure to air

pollution (85), as well as higher day- and night-time temperatures

caused by a lack of (green) vegetation, dense architecture, and a

higher temperature absorbance by urban surfaces (173). Urban

residents are also exposed to more extreme weather events (e.g.,

thunderstorms) as urban areas intensify such weather events,

combined with the fact that cities are often located close to water

(i.e., rivers, sea), which increases the likelihood for ﬂoods (79).

Additionally, urban life can be a stressful environment in itself,

due to overpopulation, noise, crime, social stress, loneliness,

and lower social support (85, 174). This diﬀerential exposure

to climate and environmental stressors can render vulnerable

individuals more susceptible to various physical and mental

health conditions.

Indigenous People

Indigenous communities, particularly those living in remote

areas, have a higher vulnerability to the climate and

environmental crisis (166, 172). This includes individuals

living in regions of the North (e.g., Inuit in Canada) who are

(among other factors) aﬀected by melting ice and alterations

in ﬂora and fauna; as well as Indigenous Australians who are

aﬀected by heat waves and bushﬁres (15, 172). The elevated

vulnerability of Indigenous communities is due to their close

dependence on and bond with nature for living, culture, and

spirituality (48). Other vulnerability factors include susceptibility

to poverty, a higher disease burden, low quality of infrastructure,

and geographical remoteness that limits access to health-related

(emergency) services (172).

Children and Adolescents

Minors are particularly vulnerable to the health impacts of the

climate and environmental crisis: “According to the limited

results from WHO, children under 5 years of age suﬀer the most

from the consequences of climate change, with 88 percent of

lost DALYs (disability-adjusted life years) attributable to climate

change occurring in this age group in both developed and

developing countries.” [(175), p. 33]. Ecological stressors can

directly impact children and adolescents, for example, through

natural disasters, via water-borne diseases, or air pollution.

For instance, research on air pollution found that adolescents

were vulnerable to the development of respiratory conditions

in response to environmental toxins [e.g., (176)]; with other

studies reporting evidence of cognitive dysfunction, damage in

the prefrontal cortex area, or slower maturation [for a short

review see (90)]. Such health impacts can aﬀect the mental

health of children and adolescents by interacting with existing

mental health issues or by causing psychological sequelae (59,

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177). Ecological stressors can also indirectly impact children

and adolescents, such as through climate-related socio-economic

hardship or migration (59); or through a lack of greenness

exposure during early development, which has been linked to

lower visuo-motor and language development [for a review

see (151)].

Several explanations can be attributed to the increased

vulnerability of minors. A major factor is that of the 2.2

billion children living worldwide, 1.9 billion are living in

developing countries (178), many of which are disproportionally

aﬀected by ecological stressors. Another major risk factor is the

biopsychological developmental phase. Children and adolescents

have an underdeveloped physiology, limited cognitive and

emotional abilities to deal with stressful circumstances, and are

dependent on others [e.g., (74)]. As a consequence of these

aspects of the biopsychological developmental phase, children

and adolescents have a heightened vulnerability to stress. Stress

experiences during childhood and/or adolescence can impact

the brain structures and functions of the aﬀected minors

(179). This can impact their psychological development (e.g.,

emotion regulation issues, poorer cognitive abilities, learning and

adjustment issues, or behavioral disorders) and increase their

vulnerability to future stress experiences (74).

Older Adults

Older individuals are more vulnerable to climate and

environmental stressors. For example, due to decreased mobility,

functional limitations, increased frailty, and multimorbidity,

older adults have a decreased likelihood to escape and survive

(injuries from) disasters [e.g., (180)]. This can be seen in the

age-bias of the fatalities from Hurricane Katrina: almost 50% of

the deceased were older than 75 years, and up to 85% were older

than 51 years (181). Older age was also found to be a meaningful

predictor of higher posttraumatic stress after Hurricane Sandy

(171). In addition, older individuals have a higher risk for the

development of depression in response to climate change-related

food insecurity (84).

Older adults are also more susceptible to extreme heat events

(116). For example, research has linked warmer temperatures to

higher suicide rates in older adults (182). Several explanations

can account for the higher heat-related morbidity and mortality

in older individuals: First, older individuals have a decreased

physiological ability for thermoregulation, as well as the ability

to sense, respond to, and recover from dehydration (116, 173).

Second, higher age is linked to a higher prevalence for chronic

health conditions, which can compound heat-related illnesses.

Third, older adults have more heat-related risk factors, such as

living alone, or smaller social networks (116, 173). Together, these

aspects can increase older adults’ vulnerability to (heat-related)

ecological stressors.

Female Gender, i.e., Those Who Identify as Female

Women are considered to be more vulnerable to the eﬀects of

the climate and environmental crisis: “Climate change acts as a

threat multiplier on already existing issues associated with gender

inequality to increase the problem of marginalization faced by

women” [(183), p. 2]. The reasons for this vulnerability vary

depending on region and culture. In Europe, for instance, the

higher vulnerability for women can be understood in relation

to the increased likelihood of heat wave related fatalities in

women [for a review see (115)]. In developing countries, the

higher vulnerability can be linked to the structural disadvantages

faced by many women, such as limited ﬁnancial resources,

and livelihoods that are largely dependent on the climate.

The diﬀerential susceptibility of men and women can also

be understood in relation to gender roles and discrimination

in patriarchal societies, which can increase the risk exposure

for women (183). For example, in many developing countries,

fetching water is a physically straining task often carried out by

children, girls, and women. This task is associated with many

health risks, including falls, injuries, pain, fatigue, and a general

lower well-being (82). It can be additionally dangerous due to a

heightened risk for the sexual assault of females on the way to

fetch water [for a review see (83)]. These factors can increase

women’s vulnerability to climate and environmental stressors.

Pre-existing Physical and Mental Health Conditions

Individuals at higher risk to be aﬀected by the climate and

environmental crisis (i.e., to present with psychopathology),

include those with pre-existing health conditions and disabilities,

those with higher stress levels or previous exposure to traumata,

and those relying on (psychotropic) medication [e.g., (171)].

Individuals with (chronic) physical health conditions, such

as cardiovascular or respiratory diseases or obesity, have a

higher risk for heat-related morbidity and mortality, due to

altered thermoregulation (116, 173). In addition, individuals with

disorders that interfere with behavior, mobility, and/or awareness

(e.g., dementia, Parkinson’s disease) also have a higher risk for

heat-related mortality (115). Furthermore, pre-existing mental

health conditions can increase susceptibility to the impact of

extreme weather events, such as an increased likelihood for

PTSD (65). However, evidence on this is mixed. For example,

in the study of estimated PTSD following Hurricane Katrina,

no relationship was found between pre-existing psychopathology

and PTSD trajectories (62). Certain medications can also

aﬀect thermoregulation or thirst-regulation (117, 118, 173).

For instance, research on the 2003 heat wave in France

revealed that anticholinergic, antipsychotic, and anxiolytic drugs

were independently linked to hospitalization during the heat

wave. This may be due to the detrimental impact of these

medications on physiological thermoregulation (e.g., inhibited

sweating) and behavioral thermoregulation (e.g., reduced water

intake—drinking behavior) (184). This highlights the increased

vulnerability to the impact of ecological stressors for individuals

with pre-existing physical and mental health conditions.

Low Socio-Economic Status

Individuals with lower socio-economic resources, i.e., those with

lower income, social status, or educational attainment, are more

vulnerable to climate and environmental stressors (79, 165). For

example, low-wage and extremely poor urban residents who have

no or very limited isolation, as is the case in slums, are more

strongly aﬀected by heat or heavy rain (79). Low-income and

education are also linked to a higher heat-related mortality risk

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[for a review see (116)]. Furthermore, increasing temperatures

can cause heat stress and decrease work productivity and

increase the likelihood for injury, which disproportionally aﬀects

countries with warmer climates. For example, a national cohort

study in Thailand with almost 60,000 workers, showed that one-

ﬁfth of the workers reported occupation-related heat stress and

that this was meaningfully linked to a higher risk of injuries (109).

In addition, individuals with disadvantaged backgrounds often

live in areas with reduced access to green spaces and lower tree

canopy cover, with decreased exposure to the health-promoting

inﬂuence of greenness [e.g., (157)]. These multi-faceted aspects

of low socio-economic status can increase vulnerability to the

impact of the climate and environmental crisis.

Adaptation

There is a repeatedly observed, yet insuﬃciently understood

heterogeneity in how individuals respond and adapt to adversity.

While it is essential to consider risk and vulnerability factors

in explaining this heterogeneity, protective factors are equally

as important in understanding interindividual diﬀerences in

adapting to the climate and environmental crisis and the

impact on mental health. This positive adaptation and potential

protective factors will be outlined in the following sections.

Resilience

Resilience can be broadly deﬁned as positive adaptation in the

face or aftermath of stress and adversity [e.g., (185)]. Resilience

is not an uncommon phenomenon and with respect to acute

disasters, it has been shown that the majority of individuals

can adapt well (22). For example, longitudinal research by Lowe

and Rhodes (169) found that more than 60% of participants

showed a resilient trajectory after Hurricane Katrina. Another

longitudinal study with Mexican individuals aﬀected by a large-

scale ﬂood found that 35% of participants showed a resistant

trajectory (stable, mild symptomatology), and 31% showed a

resilient trajectory (initial severe symptomology that declined to

a moderate symptom level) (186). Evidence of resilience may also

be seen for gradual changes to the natural environment, such as

that experienced by the Inuit in Canada: “. . . there is nothing else

(we can do), we can’t dwell on it. Then we would be all suicidal.

You just have to do the best you can with what change is coming”

[(15), p. 265]. Such resilience varies as a function of internal and

external factors [e.g., (187)].

Internal psychological factors that have been linked to higher

adaptability to the climate and environmental crisis include self-

eﬃcacy (188), sense of optimism, being informed, social support

(63, 169), and increased (access to) pre-disaster resources (189).

In climate scientists, a source of resilience can be seen in the sense

of community, i.e., the feeling that one is not alone in combating

the climate change but that one is working in a community with

a shared goal; this can assist in increasing the perception of being

supported and validated (190).

External resilience factors include the general resilience of

communities, as well as speciﬁc aspects, such as how prepared

the health-care sector is to handle disasters and environmental

risks (68). An important external factor is vicinity or exposure

to surrounding greenness and outdoor blue spaces, such as

lakes (105, 191, 192). A large and steadily increasing number

of studies demonstrate the health-promoting eﬀects of being

in and interacting with nature [e.g., (153, 154)], of viewing

natural landscapes [e.g., (193)], or even listing to natural sounds

[e.g., (194)]. Increased exposure to environmental greenness

has been linked to lower psychological distress, depression

and anxiety disorders, and schizophrenia incidence (105, 157,

195); as well as to slower cognitive decline in middle-aged

individuals (191); and improved self-reported mental health

in urban settings [see (196)]. Greenness is also important

for healthy development in children, with a recent systematic

review identifying an association between exposure to greenness

and decreased emotional and behavioral diﬃculties, particularly

inattention and hyperactivity (151). Furthermore, surrounding

greenness can decrease the ambient and surface temperature

in cities, and thus counteract the negative health eﬀects of

urban heat (105). Greenspace has also been found to physically

reduce exposure to (traﬃc) noise and to buﬀer the noise-induced

psychological stress response (154).

The positive impact of nature on emotional well-being has

also been observed for Indigenous people who have close bonds

with the land. For example, research with Inuit in Canada found

that if they were unable to be outside and interact with nature,

participants reported feelings of craving and being caged inside

like an animal, which was stressful and depressing (15, 135).

In contrast, being closely connected to nature elicited positive

emotions and increased the feeling of being healthy. For instance,

one participant reported that “. . . the air and the land takes

a lot of your feelings away and replaces the negative energy

with the positive energy, nature . . . ” [(15), p. 262]. The above

research suggests that certain (internal and external) factors

can foster positive adaptation (i.e., resilience) to climate and

environmental stressors.

Adversity-Related Positive Development

Some individuals may not only adapt well in the face

of adversity, but may also experience positive interpersonal

development [e.g., (197)]. An example of this can be seen

in the research on Hurricane Katrina (198). Results not only

showed a signiﬁcantly lower conditional prevalence of suicidality

post-hurricane (suicidal ideation: 0.7%; suicidal plans: 0.4%),

compared pre-hurricane (suicidal ideation: 8.4%; suicidal plans:

3.6%); but also revealed that suicidality was linked to aspects of

posttraumatic growth, such as becoming aware of one’s inner

strength or developing faith in the capability to rebuild one’s

life (198). Another example is provided by a recent qualitative

study that involved interviews on lived experiences by individuals

who were personally aﬀected by severe wildﬁres in Canada: It

was found that besides negative feelings of distress, anxiety and

uncertainty by their evacuation and isolation, positive aspects

were reported, too, such as the creation of opportunities for

supporting and caring for one another (61).

Taken together, the above research indicates that while it

is important to consider risk and vulnerability to ecological

stressors, protective factors can also facilitate positive adaptation

and even development in response to the climate and

environmental crisis.

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METHODOLOGICAL CONSIDERATIONS

AND FUTURE DIRECTIONS

In the exploration of the literature on climate change and mental

health, methodological limitations must also be considered to

inform directions for future research.

Methodological Limitations

Given the vast complexities of the two factors involved (i.e.,

anthropogenic climate change and mental health), attributing

a causal link is diﬃcult and poses multiple methodological

challenges (22). While an increasing number of studies have

examined the adverse mental health eﬀects of the climate and

environmental crisis, much of the available data is based on

(retrospective) cross-sectional research, or qualitative, case-study

and ethnographic designs. These studies lack information on

trajectories and long-term eﬀects and prohibit the establishment

of causal connections (83). Baseline data (i.e., pre-disaster mental

functioning) is often lacking [valuable exceptions are (63, 64,

66)]. This hinders statements about change in psychopathology

in response to the event, as well as the examination of predictors

related to interindividual variability in adaptation (199). The

mental health impact of acute, isolated events (e.g., hurricanes)

can be more easily assessed, such as by examining the change in

mental functioning prior- (if available) to post-disaster. However,

the attribution of (all) these extreme weather events to climate

change is problematic; as while their increased frequency or

power may vary as a function of the changing climate, their

occurrence may not (8, 131). Attributing the mental health

impact of sub-acute and chronic phenomena is also challenging,

as they often do not have a deﬁned beginning or ending and

their impact is often experienced indirectly due to the subtle,

gradually-evolving, and accumulating nature of these types of

events (8).

With regard to mental health, the majority of studies assessed

mental health disorders with self-report screening instruments,

which are prone to subjective bias, are less precise than structured

clinical interviews, and limit conclusions to probable/estimated

mental health disorders. In addition, many studies did not

include control groups, or neglected to control for relevant

confounding inﬂuences (67, 85). It should also be taken into

consideration that mental health disorders can vary as a function

of norms and cultural contexts and their etiology depends

on multiple biopsychosocial factors (11). Furthermore, the

assessment of adverse mental health eﬀects in post-disaster

populations is often aﬀected by sample biases. For example, those

who are most marginalized, those aﬀected most by (post)disaster-

related stressors, and those with the highest psychopathological

burden are less likely to participate in studies, which bears the

potential for underestimation of mental health eﬀects (62, 170).

Mental health disorders are also stigmatized in many cultures,

which can impact disclosure and assessment (200).

Recommendations for Future Studies

In addition to addressing these methodological limitations

identiﬁed in previous studies, some speciﬁc recommendations

should also be considered for future research. A stronger focus

should be placed on underlying processes, particularly emotional,

cognitive, and behavioral processes that have previously been

neglected. Future studies should also examine potential positive

changes that can occur as a result of the climate and

environmental crisis, such as post-disaster psychological growth;

increased sense of meaning, social engagement, and social

cohesion compassion; or increased engagement with mitigation

activities (8, 38, 198).

Going forward, mixed-methods approaches are

recommended, as they combine qualitative and quantitative

methods that are suitable to assess complex relationships, such

as the adverse mental health impact of sub-acute weather events

(166). Mixed-methods also allow for a person-centered approach

and an in-depth analyses and understanding of rich data, as well

as the quantiﬁcation of the mental health burden (67). There is

also a need to move beyond the current focus of conventional

epidemiology, which “. . . focuses too much on the individual,

on direct or proximate causes, on the past and present, and

on current states of being; and too little on whole populations,

indirect and distal inﬂuences, the life course and the future,

and the dynamics of health across contexts” [(131), p. 283].

Future research could apply a systems approach (i.e., combining

various perspectives from multiple academic disciplines and

perspectives) to better foster an understanding of the intertwined

factors and processes underpinning climate change and mental

health [see (131)]. With regard to data assessment analysis

methods, large-scale, longitudinal, population health studies

and experimental epidemiological studies could best ﬁt this

approach, using network- and data-driven analyses, as well as

agent-based and dynamic models (131).

CONCLUSION

Climate change is not only one of this century’s major challenges,

but is probably one of the most important challenges in the

history of humankind. Given the dependence of humans

on a healthy environment (124), the mitigation of climate

change and protection of the natural environment must

become a top priority. A change toward the responsible

management and protection of the natural world and

a more sustainable lifestyle may ultimately foster better

mental health [e.g., (5)]: “The good news is that such

transformative change, with social and economic justice for

all, promises far greater human well-being than does business as

usual” [(3), p. 11].

A growing number of studies are examining the mental

health impact of the anthropogenic climate change, pollution,

and destruction of the natural environment. However, the

climate and environmental crisis, as well as mental health, are

highly complex topics; and as this ﬁeld of study is still in

its early days, the underlying processes remain insuﬃciently

understood. This synergy of literature has aimed to provide

a current summary of existing research on the mental health

impact of the climate and environmental crisis from the

perspective of clinical psychology. Given the urgency of the

current situation, it is of crucial importance that future research

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Mental Health in Climate Crisis

examines this neglected relationship in light of the identiﬁed

processes and pathways, including the consideration of potential

vulnerability and protective factors. We herewith call for

increased investigations into this topic by clinical psychologists,

within the context of this rapidly growing research area of

Clinical Ecopsychology.

AUTHOR CONTRIBUTIONS

MT: deﬁnition, conceptualization, writing of original draft,

and project administration. NR and SR: writing parts of the

manuscripts, reviewing, and editing. All authors contributed to

and have approved the ﬁnal manuscript.

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Conﬂict of Interest: The authors declare that the research was conducted in the

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potential conﬂict of interest.

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