Climate change and mental health: A causal pathways framework

Abstract

Climate change will bring more frequent, long lasting and severe adverse weather events and these changes will affect mental health. We propose an explanatory framework to enhance consideration of how these effects may operate and to encourage debate about this important aspect of the health impacts of climate change.
Literature review.
Climate change may affect mental health directly by exposing people to trauma. It may also affect mental health indirectly, by affecting (1) physical health (for example, extreme heat exposure causes heat exhaustion in vulnerable people, and associated mental health consequences) and (2) community wellbeing. Within community, wellbeing is a sub-process in which climate change erodes physical environments which, in turn, damage social environments. Vulnerable people and places, especially in low-income countries, will be particularly badly affected.
Different aspects of climate change may affect mental health through direct and indirect pathways, leading to serious mental health problems, possibly including increased suicide mortality. We propose that it is helpful to integrate these pathways in an explanatory framework, which may assist in developing public health policy, practice and research.

Full text

ORIGINAL ARTICLE
Climate change and mental health: a causal pathways framework
Helen Louise Berry •Kathryn Bowen •
Tord Kjellstrom
Received: 18 December 2008 / Revised: 23 November 2009 / Accepted: 1 December 2009 / Published online: 22 December 2009
ÓBirkha
¨user Verlag, Basel/Switzerland 2009
Abstract
Objectives Climate change will bring more frequent, long
lasting and severe adverse weather events and these changes
will affect mental health. We propose an explanatory
framework to enhance consideration of how these effects
may operate and to encourage debate about this important
aspect of the health impacts of climate change.
Methods Literature review.
Results Climate change may affect mental health directly
by exposing people to trauma. It may also affect mental
health indirectly, by affecting (1) physical health (for
example, extreme heat exposure causes heat exhaustion in
vulnerable people, and associated mental health conse-
quences) and (2) community wellbeing. Within community,
wellbeing is a sub-process in which climate change erodes
physical environments which, in turn, damage social envi-
ronments. Vulnerable people and places, especially in low-
income countries, will be particularly badly affected.
Conclusions Different aspects of climate change may
affect mental health through direct and indirect pathways,
leading to serious mental health problems, possibly
including increased suicide mortality. We propose that it is
helpful to integrate these pathways in an explanatory
framework, which may assist in developing public health
policy, practice and research.
Keywords Climate change Mental health 
Public health Adaptation
Introduction
Our world is facing potentially catastrophic climate change
(Intergovernmental Panel on Climate Change 2007) and
this has the capacity to damage human health in multiple
ways (Costello et al. 2009). Human life has evolved within
a temperature, humidity and solar radiation environment
that has not varied much over thousands of years; we, and
the flora and fauna with which we share our planet, have
limited capacity to adapt to rapid or extreme climatic
changes (McMichael 1993). However, as climate science
advances, it is becoming evident that we may have to
prepare for dramatic changes, mostly for the worst
(McMichael et al. 2006b). We have begun to consider
some of the ways in which our health may be affected: our
greatest challenges may come from lack of food and
drinkable water, wider spread of certain vector-borne dis-
eases and increased heat exposures (McMichael et al.
2004). However, little consideration has been given to how
climate change may affect mental health, perhaps due to its
‘neglected’ (Horton 2007) status as the poor relation of
health (Hickie 2002). Although it is important not to
pathologise normal psychological reactions to adversity
and disaster (Horwitz and Wakefield 2007), we do need to
consider the mental health implications of climate change
This paper belongs to the special issue ‘‘Climate changes health’’.
H. L. Berry (&)K. Bowen T. Kjellstrom
National Centre for Epidemiology and Population Health,
College of Medicine, Biology and Environment,
The Australian National University, Canberra, Australia
e-mail: Helen.Berry@anu.edu.au
H. L. Berry
Centre for Rural and Remote Mental Health, School of Medicine
and Public Health, The University of Newcastle,
Newcastle, Australia
H. L. Berry
Centre for Research and Action in Public Health,
University of Canberra, Canberra, Australia
Int J Public Health (2010) 55:123–132
DOI 10.1007/s00038-009-0112-0

and why this aspect of health has received so little atten-
tion. The aims of this paper are to highlight the importance
of the possible impacts of climate change on mental health
and to propose a framework for better understanding on
how climate change may affect mental health.
Climate change and health
The latest evaluation by the Intergovernmental Panel on
Climate Change (2007) has concluded that greenhouse gases
from human activity are a major cause of continuing global
climate change. Global temperature will increase, perhaps
between 1.8 and 4.0°C, by 2100 (Intergovernmental Panel
on Climate Change 2007), depending on which actions are
taken to mitigate greenhouse gas emissions. This will mean
more variable and extreme weather conditions (mainly
extremely hot or violent weather but, in some places, also
extremely cold weather). It is essential to note that estimates
of average global climate change mask the variability of
impacts and extremes that some locations will experience
(Kjellstrom 2009a). For instance, in Cairo and Athens, at 4.8
and 5.3°C per century, respectively, temperatures are rising
more rapidly than the global average (Fig. 1).
Extreme heat exposure will be associated with sub-
stantial fatalities and injuries (Kovats and Hajat 2008),
particularly where other extreme weather events also occur,
such as floods and droughts (Huq et al. 2007). Cases of
diarrheal and vector-borne diseases, and famine, will
increase with rising temperatures (Intergovernmental Panel
on Climate Change 2007; McMichael 2003); and increas-
ing temperatures in combination with high air humidity
will lead to heat exhaustion, heat stroke and fatalities
during heat waves, especially among the elderly (Kovats
and Hajat 2008) and among younger people undertaking
heavy labour (Kjellstrom 2009b). An important concern is
that the effects of climate change may be stronger for those
populations at socioeconomic disadvantage (Commission
on Social Determinants of Health 2008) exacerbating the
already inequitable distribution of health challenges (Friel
et al. 2008), particularly among indigenous peoples (Salick
and Byg 2007).
Climate change and pathways to mental health
Mental health is a key component of the World Health
Organization’s (WHO) definition of health as ‘a state of
complete physical, mental and social wellbeing and not
merely the absence of disease or infirmity’ (World Health
Organization 1948). More elegantly and pragmatically,
mental health may be considered a person’s ability to think,
to learn, and to live with his or her own emotions and the
reactions of others (Herrman 2001). The first definition
views mental health as a stable state of positive wellbeing
while the second more properly implies a dynamic con-
tinuum. Mental health problems are part of this continuum
of mental health. They differ in their causes, symptoms,
effects and treatment, but are all characterized by altera-
tions in thinking, mood or behavior, and associated distress
or impaired functioning. Some mental health problems are
uncommon (such as schizophrenia, other psychoses, bipo-
lar disorder and some anxiety and personality disorders),
some are common (including depression and other mood
disorders, some anxiety disorders, psychological distress,
substance use and eating disorders, dementia and other
forms of cognitive decline), and all may be severe and/or
enduring (Berry et al. 2007a).
Different types of extreme weather events appear to
relate to somewhat different mental health impacts, parti-
cularly at onset. The link between extreme anxiety reactions
(such as post-traumatic stress disorder, or PTSD) and acute
weather disasters, such as floods (the most common disas-
ters at global level), forest fires, heat waves and cyclones, is
Cairo 1980-2007
y = 0.0262x + 27.437
y = 0.0484x + 21.11
y = 0.0658x + 15.353
10.00
12.00
14.00
16.00
18.00
20.00
22.00
24.00
26.00
28.00
30.00
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
Athens 1980-2007
y = 0.0409x + 21.661
y = 0.053x + 17.222
y = 0.0514x + 13.154
10.00
12.00
14.00
16.00
18.00
20.00
22.00
24.00
26.00
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
Fig. 1 Temperature (°C) time trends in two cities, Cairo and Athens,
based on the daily weather station data, and including linear
regression equations (from Kjellstrom and Lemke, unpublished).
Each plot shows annual average of daily averages; middle line is
average temperature, and the other two lines are averages of
maximum and minimum temperatures in daily data for each year;
the equations describe the fitted linear trend as change per year, since
1980: x=year -1980, y=temperature
124 H. L. Berry et al.

well established (e.g. Salcioglu et al. 2007), as are the
emergency and other response procedures that are deployed
when they occur. However, not much research has been
conducted into their long-term effects. However, long-term
anxiety and depression, as well as PTSD, increased
aggression (in children) and perhaps even suicide, have
been found to be associated with floods (Ahern et al. 2005).
There is almost no quantitative epidemiological evi-
dence for the mental health effects of sub-acute weather
disasters, such as long-term drought (Berry et al. 2008).
But it may be expected that the same loss of people,
property and possessions, dislocation from community and
disruption of key social connections that precede or
amplify the development of mental health problems fol-
lowing acute disasters would apply in response to chronic
disasters of equivalent magnitude. Symptomatology related
to chronic loss and failure, such as helplessness depression,
chronic psychological distress and generalized anxiety may
be expected (Coelho et al. 2004). This is because, com-
monly, these mental health problems develop following
multiple adversities (Brugha and Cragg 1990), and slow-
creeping climate change-related weather events, such as
drought, tend to accumulate adversities.
Fritze et al. (2008) have also proposed that climate
change will have significant mental health implications
noting the psychological distress and anxiety about the
future that may result from acknowledging climate change
as a global environmental threat. They describe the
immediate (direct) mental health impacts of climate
change: the disruptions that vulnerable communities, in
particular, face with regard to the social, economic and
environmental determinants of mental health; and the
future distress and anxiety that climate change may create
on an individual level (Fritze et al. 2008).
Berry et al. (2008) and Fritze et al. (2008) concur that
climate change will have both direct and indirect effects on
mental health but there is, currently, no integrative
framework to guide research or policy making. Figure 2
illustrates putative direct and indirect relationships among
factors. Climate change may affect mental health directly
by exposing people to the psychological trauma associated
with higher frequency, intensity and duration of climate-
related disasters, including extreme heat exposure (Kjell-
strom 2009a), and also by destroying landscapes, which
diminishes the sense of belonging and solace that people
derive from their connectedness to the land (Higginbotham
et al. 2007). In addition, indirect effects may occur via two
further pathways. Climate change may affect (1) physical
health, through increased heat stress, injury, disease and
disruption to food supply, and (2) community wellbeing,
through damage to the economic and, consequently, the
social fabric of communities.
Direct effects of climate change on mental health
Acute weather events
Most research into the mental health impacts of weather
events has concentrated on acute events such as,
Trauma,
Solastalgia
Causal, reciprocal
relationship
Damage to landscape
and agriculture
Direct (smoke, burns,
heat)
Indirect (food supply)
Loss of livelihoods,
poverty, isolation,
alienation, grief,
bereavement, displacement
COMMUNITIES
PHYSICAL HEALTH
CLIMATE CHANGE-RELATED DISASTERS
(SPECIFIC ACUTE, SUB-ACUTE AND CHRONIC EVENTS)
Economic, social
demographic impacts
MENTAL HEALTH
Acute/chronic
High/low prevalence
Local cultural, economic, social, developmental and environmental context
Fig. 2 Framework showing
putative causal pathways
linking climate change and
mental health
Climate change and mental health 125

earthquakes, floods, fires and hurricanes, and associations
with the onset of PTSD. Because climate change is asso-
ciated with an increase in the frequency and severity of
these acute weather events, people will be increasingly
exposed to the precursors of PTSD—danger, injury and
death, including harm to significant others. Consistent with
pathways models of mental health, PTSD is sensitive to a
range of exposure and predisposing social and emotional
factors, with young people particularly vulnerable (Sal-
cioglu et al. 2007). In addition to the development of severe
anxiety disorders, traumatic exposures can also cause
reactions ranging from general somatic and mental health
problems, followed by resilient recovery to several types of
enduring, severe psychopathology (Norris et al. 2002), as
well as loss of resources (Freedy et al. 1994) and sub-
stantial psychological distress (Beaudoin 2007; Wickrama
and Wickrama 2008).
Extreme heat events will be especially common as
global temperatures rise and these events may also be
associated with a general increase in aggression (Anderson
and Anderson 1998). Increasing temperatures (especially
lengthy spells of hot weather) have been associated with
higher rates of criminal and aggressive behavior (Brearley
1929; Cheatwood 1995; Cohn et al. 2004) and higher sui-
cide rates (Maes et al. 1994). Extreme heat events may also
be linked to suicide and psychiatric and other hospital
admissions. In a recent meta-analysis, Bouchama et al.
(2007) concluded that pre-existing mental health problems
tripled the risk of any-cause mortality during a heat wave.
In Adelaide, Australia (Nitschke et al. 2007), heat wave-
related hospital admissions increased for mental and
behavioral disorders, including organic illnesses, dementia,
mood disorders, anxiety, stress-related and somatoform
disorders, disorders of psychological development and
senility (Hanson et al. 2008). A related issue is the physical
and psychological exhaustion caused by extreme heat
exposure (Parsons 2003), which will be a more common
feature of already hot regions of the world (Global
Humanitarian Forum 2009). Humidity has also been asso-
ciated with mental functioning. For example, it is related to
poorer concentration and elevated fatigue (Howarth and
Hoffman 1984). However, the relationships among heat,
humidity and mental health may be sensitive to local
context or confounded by research methods (Berry et al.
2008). For instance, decreasing temperatures have also
been associated with increasing aggression (Howarth and
Hoffman 1984), suggesting perhaps that significant tem-
perature deviations up or down from local norms may be
related to increasing mental health problems.
A recent review of the mental health impacts of climate
change in rural and remote Australia identified an urgent
need to understand the likely consequences of climate
change (particularly drought and long-term drying) on
mental health and wellbeing (Berry et al. 2008). The
review drew attention to a spectrum of chronic to acute
(fast onset) climate change-related adverse weather events
(see Table 1): acute events include heat waves, floods,
storms and fires, while drought is an example of a sub-
acute event. Long-term underlying drying and warming are
chronic events. The occurrence of such events is associated
with increased mental health problems. In emergencies
generally, the number of people with mental disorders is
estimated to increase by 6–11% (World Health
Organization).
Sub-acute weather events
Climate change will also be associated with an increase in
sub-acute adverse weather events, most notably with more
frequent, longer and more severe periods of extreme heat
and/or drought. At its worst, this may dislocate people
permanently from their land, creating cohorts of displaced
persons who will experience depression and trauma
(Campbell and Campbell 2007; Haq et al. 2007) associated
with loss of home, place and social networks (McMichael
et al. 2009). The IPCC has estimated that there may be 150
million such displaced persons by 2050, due primarily to
coastal flooding, shoreline erosion and agricultural degra-
dation. In addition to too little (or too much) rain, rain may
fall outside the periods in which it is needed for particular
agricultural purposes, especially for cropping, exacerbating
the underlying difficulties associated with inadequate
Table 1 Nature of weather events (acute vs. chronic) and putative pathways to effects on mental health (direct vs. indirect)
Acute weather event (e.g. increased frequency of cyclones) Sub-acute weather event (e.g. more extremely hot days,
droughts)
Direct effects
on mental
health
More frequent exposure to physical danger due to storms or
floods; elevated rates of acute anxiety disorders
More frequent exposure to chronic stress, e.g. from long
periods of extremes of heat or lack of (clean) water; elevated
rates of violence and aggression
Indirect
effects on
mental
health
More frequent and/or severe damage to homes and physical
infrastructure, including community buildings (halls,
churches, schools); physical injury to self or significant
others; elevated rates of anxiety and mood disorders
More frequent and/or severe physical health impacts and
damage to livelihoods and soft social infrastructure
(disruption of networks, lack of time to socialize); elevated
rates of chronic mood disorders and suicide ideation and
attempts
126 H. L. Berry et al.

precipitation (Intergovernmental Panel on Climate Change
2007).
Heat exposures in working environments are of great
significance: they reduce people’s capacity to undertake
physical (Bridger 2003; Kerslake 1972; Kjellstrom et al.
2009d), mental task capacity is diminished (Ramsey 1995)
and the risk of accidents is increased (Ramsey et al. 1983).
The primary cause of these effects is excessive core body
temperature (Leithead and Lind 1964); dehydration due to
inadequate fluid intake while sweating is also important
(Schrier et al. 1970). The loss of work capacity due to
increasing heat exposure while working (particularly out-
doors) and resulting loss of income (Kjellstrom 2009b)is
also likely to cause mental health problems for many
millions of people.
Indirect effects of climate change on mental health
Impacts via physical health
Physical health problems are causally and reciprocally
associated with the development of mental health problems
(Miller et al. 2009; Prince et al. 2007), particularly among
vulnerable groups, such as older people (Katz 1996) and
indigenous people (Berry 2009). Mental health problems
are among the risk factors for communicable and non-
communicable diseases, increasing the likelihood of their
development. The reverse is also true with: for example,
obesity has been associated with increase in depression,
bipolar disorder and panic disorder (World Health Orga-
nization 2009).
Impacts via the physical environment
Long periods of high temperatures, heat and drought-
related events (such as fires) can be expected to increase, as
can flood and related events (such as landslides). These will
be accompanied by consequential environmental risk fac-
tors, such as increased smoke, pollen density, dust
(McMichael et al. 2006a) plant disease, and infestations.
The quality and availability of water for human and live-
stock consumption may be compromised, with possible
increases in water-borne disease (Rose et al. 2000). In
developing countries, which will endure the bulk of
adverse climate change, many people may be forced from
land that they can no longer farm into urban slums (UN
Habitat 2006); here, the additional heat exposures due to
climate change and the indirect health risks (such as
extended lack of clean drinking water) are much greater
than in other parts of cities (World Health Organization
2008b). These threats to physical health will directly affect
mental health and also compound the underlying risks to
mental health inherent in living in urban slums (Berry
2007).
Environmental relationships to health have often been
narrowly articulated in terms of biophysical conditions
(Horwitz et al. 2001). There is, also, an important rela-
tionship between sense of place, the environment and
human wellbeing, sometimes expressed as ‘biophilia’
(Gullone 2000; Wilson 1984) and ‘solastalgia’ (Higgin-
botham et al. 2007). Biophilia describes the relationship
between humans and their environmental conditions, while
solastalgia describes the distress, the loss of solace, caused
by degradation of the environment, home and sense of
belonging.
Climates everywhere are characterized by daily and
seasonal variations and we are acclimatized to these; but
climate change-induced increases in climate variability will
not be spread evenly across the day or the year. Instead,
there will be increased extremes. This will increase the
variability in climate-related mental health problems. For
example, seasonal variation in mood has already been
documented, with seasonal affective disorder, depressive
symptoms, bulimia nervosa, anxiety disorders and other
mental health problems usually peaking in the cold season
when there is limited sunlight (Magnusson 2000). Where
the climate warms, seasonal affective disorder may reduce
somewhat, while it may be exacerbated in regions that
receive fewer hours of sunlight. Periods of drought in rural
areas over spring (a significant time for agricultural pro-
duction) are associated with a reduction in life satisfaction
(Carroll et al. 2009) and more of these shifts in the timing
of droughts can be expected (Berry et al. 2008).
Impacts via the social environment
In communities dependent on agricultural production
(which are more common in least developed countries and
among Indigenous peoples; Agriculture Food Organization
2008), climate change may, in some cases, particularly in
vulnerable places and among vulnerable populations
reduce agricultural productivity and the viability of agri-
cultural support industries. For example, extreme heat
exposure in farm fields reduces agricultural laborers’ work
capacity (Kjellstrom et al. 2009d), further undermining
agricultural support industries which include local busi-
nesses and services and employment brokers for casual
labor (Berry et al. 2008). These losses create socioeco-
nomic hardship and subsequent poor mental health
(Dohrenwend 1990; Faris and Dunham 1939; Hollingshead
1958; Leighton 1965; Srole 1962). In Australia, in the
drought period from 2002 to 2003, GDP growth fell 1.0
percentage point, with gross value added falling by 28.5%
compared with the preceding year (Australian Bureau of
Statistics 2004). Natural disasters cost Australia A$37.8b
Climate change and mental health 127

between 1967 and 1999. All, but A$5b (earthquakes) of
these losses were attributable to climate factors (Inter-
governmental Panel on Climate Change 2007). In long-
term drought, specifically, deterioration in economic
conditions over time has been associated with depression
and demoralisation among parents (Conger et al. 1992) and
their children. Indeed, it has been proposed that socioeco-
nomic circumstances may be a more potent source of
vulnerability to poor mental health than is the rural setting
itself (Judd et al. 2002; Smith et al. 2008). Drought-prone
areas are vulnerable to chronically lower socioeconomic
status and educational attainment than are other areas and,
consequently, to higher levels of distress and learned
helplessness (Coelho et al. 2004).
Importantly, economic pressures undermine social cap-
ital that is protectively related, possibly causally, to mental
health and wellbeing (De Silva et al. 2005; Sartorius 2003;
Whitley and McKenzie 2005). Social capital is a combi-
nation of community participation and social cohesion,
with higher levels of social capital related to better health
(particularly where there are high levels of inequality), and
especially to mental health (Berry and Welsh 2009); where
increased workloads and lack of time and money-keep
people from social activities, particularly from the informal
social connections that are so important for mental health
(Berry et al. 2007b), or place pressure on important rela-
tionships, mental health problems are likely to increase.
Women may be particularly affected, being more likely
than are men (Alston and Kent 2004; Stehlik et al. 2000)to
migrate for employment or for their children’s education
,
with consequent impacts on family wellbeing.
The importance of the social impacts in indigenous
peoples and on those living in tropical low and middle-
income countries is highlighted by the examples in
Appendix.
Impacts via adaptation or mitigation
Adaptation and mitigation actions may, in themselves,
increase climate change-related mental health risks via
various causal pathways. For example, reduced car travel
by car-reliant populations would, desirably, reduce green-
house gas emissions and, possibly, increase physical
activity. For those who may stop driving to work, instead
walking or cycling, there could indeed be very substantial
co-benefits for chronic disorders, such as obesity and car-
diovascular disease (Besser and Dannenberg 2005; Frank
et al. 2004). However, travel by alternative means, whether
these are public transport, walking or cycling, may, for
some people, increase travel time; where this were the case,
commuters would have less time to spend at work or,
perhaps more likely, at home, reducing the time available
to engage with family and friends. Given that time devoted
to informal social connectedness is very strongly protec-
tively related to mental health (Berry and Welsh 2009),
increasing travel time would be related to adverse impacts
on mental health. Further, as those who are most disad-
vantaged tend to have least access to services, such as
transport, this would differentially be a disadvantage those
in most need (Currie et al. 2009). Adaptation also poses
health risks. For instance, when air conditioning is not
available, excessive heat exposure at work may require
working less in the hottest parts of the day, thus reducing
daily output. For low-paid workers, especially in devel-
oping countries where occupational health systems may
provide only limited protection (Kjellstrom and Hogstedt
2009), this may translate to reduced income. To compen-
sate, these workers may find it necessary to increase their
work hours, or to work more at night, with negative
implications for their health (Harrington 1994) and for
family life.
The role of the health system in preventing
or reducing effects
Not much is being done to address physical health needs
and even less to address mental health concerns relating to
climate change and this is not surprising. The neglect of
mental health is reflected in the inadequate level of
resources made available for mental health services (Hor-
ton 2007) and also in the poor resourcing of mental health
research (Jorm et al. 2002). Mental health resources are
‘inadequate, insufficient and inequitably distributed’
(Horton 2007 p. 806), a situation that has been called a
‘silent scandal’ (Thornicroft 2007). Mental health resour-
ces are catastrophically inadequate in low-income
countries, which have 0.05 psychiatrists and 0.16 psychi-
atric nurses per 100,000 people, as compared to 200 times
more in high-income countries (World Health Organization
2009). Despite strong evidence for expanding mental
health services and integrating them into primary health
care (Horton 2007), especially in responding to climate
change (Blashki et al. 2009), worldwide, the majority of
people (between 32 and 97%) usually do not receive any
treatment at all for a wide range of mental health problems
(Thornicroft 2007). Perhaps, there are some understandable
reasons for this. It is fair to acknowledge, perhaps, that the
complexity of mental health may account for why greater
consideration is given to physical health. Maybe there is
also a genuine lack of understanding about the importance
of mental health and its interdependence with physical
health (Horton 2007). Substantial continuing worldwide
stigma (and associated exclusion and discrimination)
linked to mental health (Sartorius 2007) may also con-
tribute to this research and policy aversion. As Horton
128 H. L. Berry et al.

(2007) writes: ‘Despite the great attention western coun-
tries pay to the mind and human consciousness in
philosophy and the arts, disturbances of mental health
remain not only neglected but also deeply stigmatised
across our societies’ (p. 806).
Yet mental health is a major and growing global concern
(Prince et al. 2007), likely constituting the second greatest
burden of non-fatal disease by 2030 (Mathers and Loncar
2006), and we cannot ignore it. Within the mental health
system, a graded spectrum of approaches, ranging from
prevention and early intervention to treatment, is needed to
properly respond to mental health needs from onset
through recovery, especially for indigenous peoples. The
WHO’s pyramid (World Health Organization 2008a) for an
optimal mix of services for mental health identifies an
appropriate range: from self-care and informal community
care; through mental health services via primary health
care; community mental health services; and the most
intensive interventions at the treatment end of the spectrum
(long-stay facilities and specialist services). This pyramid
is relevant and can be adapted to the needs of climate
change-related mental health problems.
Conclusions
The debate about the impact of climate change on human
health has, very recently, included consideration of mental
health. By increasing the frequency, severity and duration
of adverse weather events, climate change will affect
mental health via at least three pathways. It will, first,
directly affect mental health by inflicting more and worse
natural disasters on human settlements which, typically,
cause serious anxiety-related responses and, later, chronic
and severe mental health problems. Second, it will increase
the risk of injury and physical health problems which are
causally and reciprocally related to mental health. Third, it
will endanger the natural and social environment on which
people depend for their livelihoods and wellbeing. These
effects will not be felt equally by all, but will fall dispro-
portionately on those who are already vulnerable,
especially on indigenous peoples and those living in
developing countries, which will bear the brunt of adverse
climate change. The present paper proposes a framework
showing direct and indirect pathways via which climate
change may affect mental health.
The health system, broadly defined, must play an
important role in identifying possibilities for preventive
actions that reduce population vulnerability, and in acting
to support people whose mental health has been affected.
Health systems that meet WHO climate change guidelines
and achieve the millennium development goals can do
much to limit the health effects of climate change.
A continuum of approaches is appropriate, depending on
the stage of illness, ranging from prevention through
treatment and recovery. We hope that our proposed
framework may encourage further debate, and contribute a
perspective that may assist in the formulation of policy and
services for the impact of climate change on mental health.
Acknowledgments This research was supported by The Australian
National University general facilities and not by any specific research
grant.
Conflict of interest statement The authors have no conflicts of
interest to declare.
Appendix
Two case studies illustrating how climate change may
affect societal and demographic factors that may, in
turn, affect mental health security
Increasing heat exposure on working people in tropical
countries
There is a physiological limit to the ability of humans to
carry out strenuous work in hot conditions (air tempera-
tures above 37°C and at high humidity level). To prevent
heat stroke in such conditions, workers have to reduce
their work output and avoid working during the hottest
part of the day. Increasing heat exposure may, therefore,
reduce income, disrupt daily social activities and create
psychological distress. For example, we have observed
work situations at construction sites in India and shoe
factories in Vietnam where the long actual working hours
and heat exposure (requiring lengthy rest periods during
the hottest hours) demand 15–16 h of daily presence at
the workplace (Kjellstrom et al. 2009d). Increasing tem-
peratures with climate change would make this situation
worse.
Drought and long-term drying in Australia
Australia’s Bureau of Meteorology has concluded that the
severity of the recent drought, 2001–2007, was, in part, due
to the underlying warmer temperatures caused by climate
change (Nicholls and Collins 2006). The recent Kenny
Review of the Social Impact of Drought in Australia
(Drought Policy Review Expert Social Panel 2008) has
described the increased hardships that have been experi-
enced in rural lifestyles: livelihoods are at stake, and those
who are most vulnerable, geographically or socioeconom-
ically, appear to be worst affected. The stresses of lost
income, debt and damage to property have spilled over into
Climate change and mental health 129

mental health problems for some and to the tragedy of
despair and suicide for a few (Berry et al. 2008). The
severity and distribution of these mental health problems
appear, also, to have been influenced by aspects of com-
munity—resources, cohesion, resilience and external
supports; where community support has been strong,
communities appear to have fared better than where less
support has been available.
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