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CLIMATE CHANGE AND CONFLICTS (E GILMORE AND E TENNANT, SECTION EDITORS)
Climate Change and Psychology: Effects of Rapid Global Warming
on Violence and Aggression
Andreas Miles-Novelo
1
&Craig A. Anderson
1
#Springer Nature Switzerland AG 2019
Abstract
Purpose of Review An important question regarding rapid climate change concerns its likely effects on violence. Rapid climate
change is likely to produce sociological, political, economic, and psychological changes that will increase the likelihood of
violent behavior. This article examines relevant theory and research.
Recent Findings We examine three lines of research: (a) how hot temperatures directly influence aggression and violence; (b)
how rapid climate change indirectly increases adulthood violence proneness through its effects on physiological and psycho-
logical development; (c) and how ecomigration influences group-level aggression. We also discuss arguments against the effects
of climate change on aggression and violence.
Summary Research and theory reveal three ways that rapid global warming can increase aggression and violence. We describe a
model showing the relationship between rapid global warming on antisocial behaviors and risk factors for aggression and
violence.
Keywords Heat .Temp er at ur e .Violence .Ecomigration .Scarcity .Aggression .Conflict
BI pray thee, good Mercutio, let’sretire:
The day is hot, the Capulets abroad,
And, if we meet, we shall not ‘scape a brawl;
For now, these hot days, is the mad blood stirring.^
- William Shakespeare (Romeo and Juliet, Act 3, Scene 1)
There is a long history of associating heat with violence.
From Cicero (106–32 B.C.E.) to Montesquieu (1748) [1], the
link between aggressive behaviors and temperature has been
observed [2]. Modern research has confirmed this connection;
Perry and Simpson [3] reported that the rates of violent assault
(i.e., rape and aggravated assault) are significantly correlated
with temperature. The first comprehensive review of the heat
effect on violence found substantial consistency across many
data sets, some as old as 1899 [4]. As contemporary global
warming triggers multiple environmental changes, the need to
understand the likely effects on violent behavior also
increases.
Scientific communities have almost universally accepted
that human activity is directly responsible for the current rapid
increase in average global temperature [5]. Human influence
on the amount of heat-trapping Bgreenhouse gases^is the
primary causal route for increases in the planet’s temperature
and the changes witnessed in a wide range of climate/weather
events. For example, it is now widely acknowledged among
climate and weather scientists that we are likely to see at least
a 2 °C increase in average temperature by the year 2100 [5].
The consequences of a warmer planet include (among many
others) a rise in average sea level (about 2 m or 6 ft if we keep
the temperature increase to 2 °C) and an increase in the sever-
ity and frequency of droughts, tropical storms/hurricanes, and
other severe weather-related events such as major flooding
[5].
The main point of this article, however, is not to debate the
existence of human-caused rapid (in geologic terms) global
warming. Instead, our main point is to explore the implica-
tions of global warming on human aggression and violence.
We do so with two action-oriented goals in mind. One, by
delineating how global warming increases the relative fre-
quency of human violence, we hope to increase people’s
This article is part of the Topical Collection on Climate Change and
Conflict
*Craig A. Anderson
caa@iastate.edu
1
Iowa State University, Ames, USA
Current Climate Change Reports
https://doi.org/10.1007/s40641-019-00121-2
motivation to act to reduce the use of fossil fuels, to increase
sustainable energy production (such as wind and solar ener-
gy), and to explore technologies to remove greenhouse gases
from the atmosphere. Second, we hope that by explaining the
social and psychological processes involved in global
warming–induced increases in violence, we will enable gov-
ernments and non-governmental organizations (NGOs) to pre-
pare for and to mitigate some of the problems that mediate the
global warming effect on violence.
For example, we know that one major consequence of eco-
logical disasters such as prolonged drought or flooding is
ecomigration (i.e., the movement of populations caused by
ecological disasters) [6]. Furthermore, ecomigration (includ-
ing refugee crises) often creates political instability, riots, and
war (civil or between countries) [7]. Knowing that such con-
sequences of global warming are coming, we should enable
nations and NGOs to prepare to deal with the refugees and
internally displaced persons in ways that reduce the violence-
enhancing potential of future ecological disasters.
Based on well-established modern bio-social-cognitive
models of aggression and violence, our research team has
discovered three ways in which rapid global warming in-
creases the relative frequency of aggressive and violent behav-
ior [8,9,10•]. Before summarizing these, it is useful to define
critical terms. BAggression^is defined by most psychologists
as behavior that is intended to harm another human who
wishes to avoid that harm. Several aspects of this definition
warrant additional attention. First, aggression is a behavior,
not a wish, emotion, or thought. Second, the person enacting
the behavior must believe that the behavior has some reason-
able chance of actually harming the individual. Third, acci-
dental harm (e.g., tripping over an extension cord and thereby
slamming into another person) and incidental harm (e.g., pain
caused by a dental procedure) are not aggressive, because the
harm is not intended. Aggression can take many forms, such
as physical (e.g., hitting a person), verbal (e.g., calling a per-
son vile names), and relational (e.g., spreading rumors about a
person to harmtheir reputation).There are other approaches to
defining aggression, but these are not central to this article
[11].
BViolence^is typically defined as physical aggression that
is sufficiently severe to yield injury requiring medical atten-
tion. Most psychologists view aggression as existing along a
continuum, with violence being reserved for the more serious
forms of physical aggression. In other words, all violence is
aggression, but not all aggression is violence. This is an im-
portant theoretical point because it allows theory building and
theory testing to include studies of milder forms of aggression
(i.e., not violence), and makes such studies relevant to under-
standing more severe forms of aggression (i.e., violence).
Note that some scholars use the term Bviolence^in conjunc-
tion with some severe forms of aggression that are not phys-
ical, such as emotional violence. In the present article, we are
mostly concerned with physical aggression and violence, al-
though many other forms of aggression also are relevant.
As mentioned earlier, our team has uncovered at least
three ways that rapid global warming increases aggression
and violence. One is relatively direct and occurs immediately
by influencing the person’s internal state (i.e., thoughts, feel-
ings, and physiological arousal); the other two are less direct.
Of these two indirect paths, one involves risk factors known
to increase the likelihood that a young person (from concep-
tion through adolescence) will become prone to violence.
The other involves risk factors acting at the group level,
factors that lead to intergroup conflict. We now turn to these
three ways that rapid global warming increases aggression
and violence.
In Fig. 1, we display a simplified model illustrating how
rapid global warming affects key weather, environmental, and
economic factors. In turn, these factors influence the three
routes by which global warming can increase violent behavior.
The most direct route is through direct effects of heat stress on
people’s current state of irritability. The other two routes are
more indirect and arise from global warming’s effects on fail-
ing crops, natural disasters, and economic instability.
Direct Effects of Heat on Individuals
Psychologists and sociologists have been studying the relation
between heat (uncomfortably warm temperature) and aggres-
sion for some time now [2,12,13]. Although ethical consid-
erations prevent researchers from conducting experimental
studies that measure the extreme types of violent behavior
seen in war or violent crimes, researchers can experimentally
examine how uncomfortable temperatures can affect individ-
uals’thoughts, perceptions, feelings, and mildly aggressive
behavior [14••]. Furthermore, there have been numerous
non-experimental studies of the heat-violence relation using
a wide range of study designs, statistical controls, and violent
behaviors. By looking at the data collected from all of these
studies, we get a consistent and convincing overarching view
of the psychological and sociological relations between tem-
perature and aggression/violence. Basically, there are three
types of studies that have tested the heat-aggression hypothe-
sis: (a) true experimental studies, in which participants are
randomly assigned to hot or comfortable-temperature condi-
tions; (b) geographic region studies, which compare violence
rates across geographic regions that differ in climate; and (c)
time period studies, which compare violence rates across time
periods that vary in temperature. All three types converge on
the same general finding that heat stress increases aggression
and violence.
The primary—and most thoroughly researched—means by
which heat stress has this effect is that uncomfortably warm
temperatures increase aggressive thoughts and feelings, or
Curr Clim Change Rep
what we call Birritability.^Although this increase in irritability
is subtle, it can increase aggressive behavior through well-
known processes of priming aggressive thoughts (i.e., increas-
ing the accessibility of aggressive ideas) and of the misattri-
bution of emotion (i.e., increasing the likelihood of perceiving
oneself to be angry). In other words, when in an irritable state,
minor provocation seems major, such that even trivial provo-
cations can trigger excessively aggressive responses, which in
turn can trigger an escalation of the violence cycle [8,15,16,
17••].
Experimental Studies
Studies using an experimental paradigm to study the relation
between aggression and temperature have found that even the
idea of heat will cause an increase in aggressive thoughts,
feelings, and behaviors. For example, in a study by
Wilkowski, Meier, Robinson, Carter, and Feltman (2009)
[18], participants were exposed to images related to heat and
temperature. They found that those exposed to the heat images
were more likely to judge neutral facial expressions as aggres-
sive and were more likely to think aggressively. Similarly,
priming participants with thoughts of heat make them more
likely to have aggressive thoughts or to interpret neutral be-
havior as aggressive [9]. Other experiments have found that
participants are more likely to be hostile, more likely to per-
ceive others as being hostile, and act more aggressively to-
ward another person after being randomly assigned to sit in an
uncomfortably hot room instead of a room at a comfortable
temperature [13].
One study manipulated temperature in a police training
program [19]. They found those police officers randomly
assigned to an uncomfortably hot condition were more likely
to respond to a burglary scenario by drawing their weapon and
by firing it than those who were in a comfortable-temperature
condition. Although these experiments do not show actual
violent behavior (e.g., shooting real people), they do provide
an important understanding of the fundamental relation be-
tween aggression and temperature, and in this case, a link
between heat and violence [19].
Comparing Geographic Regions
Another way to test the link between heat and aggression is to
compare violent crime rates across geographical regions that
are similar in terms of nationality, socioeconomic, and demo-
graphic characteristics. According to this research, hotter re-
gions (such as certain cities in the USA) have higher crime
rates, even after statistically controlling for other variables that
are sometimes associated with violent crime, such as poverty,
age distribution, and unemployment [4,20]. Although these
other factors frequently have independent effects on violent
behavior, some studies have found that they can also act as
Bamplifiers^for the effects of climate on aggression [6].
Global data has also been gathered to examine the relation
between heat and violence. One study gathered data from 60
different countries and concluded that temperature had an as-
sociation with violence levels, especially in places already
experiencing issues with conflict and instability [21]. The au-
thors concluded that for every degree (Celsius) increase due to
climate change, there would be an increase in homicide rates
by 6%. Other estimates note that even mild increases in tem-
perature (e.g., 1.1 °C) could result in 25,000 more severe and
deadly assaults per year in just the USA [22,23].
Comparing Violence Over Time
Examining violence rates in warmer or cooler climates in-
volves many possible confounding variables (e.g., types of
subcultures in the different regions). Although researchers of-
ten do their best to control for such confounds, plausible ex-
planations of the heat-aggression relation may remain. In re-
sponse to this interpretation problem, other studies have ex-
amined the relation between heat and violence within the same
regions over various periods of time, from hours, to days, to
weeks, to seasons, and to years. Because the cultural and de-
mographic variables within a specific region are largely un-
changed across the different time periods, any heat-related
effects that arise (e.g., hotter summers giving rise to a larger
than usual summer increase in violent crime than cooler sum-
mers) cannot be explained by regional differences in subcul-
tures of violence. In such time-period studies, we also find a
Global
Warming
#1. Direct heat
effects (e.g.,
irritability)
Failed crops,
Natural disasters,
Economic
instability,
Poverty,
Eco-migration
Increased
Heat,
Drought,
Extreme
weather, Sea
level rise,
Flooding
Violent Crime,
Intergroup violence,
Civil War,
Ter ro ris m,
International War
#3. Intergroup conflict:
Civil/political unrest,
Refugees & Internally
Displaced Persons,
Resource competition,
#2. Violence prone adults:
Prenatal & postnatal
developmental problems
Fig. 1 Three paths through which rapid global warming increases violent behavior
Curr Clim Change Rep
consistent pattern: the hotter the period, the higher the rate of
violence [4,12,24–26]. As noted, this can range from a few
hours to days, months, or years [4,24,25,27].
Bushman et al. [25,26] found that police reports from
Minneapolis showed a significant effect for both the heat
and time of day in rates of physical assault, over three-hour
time slots. Similar results were found in other cities: such as in
Brisbane, Australia when looking at domestic violence re-
ports, and in Vancouver, Canada, where physical assaults on
bus drivers were more frequent in hotter months [28,29].
Other types of aggression have been reported as increasing
in hotter periods of time as well. These include riots, intake
reports from psychiatric hospitals, more aggressive horn
honking in drivers without air-conditioned cars, and major
league baseball pitchers hitting more batters [30–34]. One
study [22] compared 59 years of FBI Crime Reports with
the National Oceanic and Atmospheric Administration’s
weather data and found that violent crime rates rose in hotter
years. They also compared crime rates during the summer to
the other three seasons,and found that in 53 of the 55 years for
which seasonal data were available, violent crime rates were
highest in the summer. The authors additionally showed that
violent crime rates rose in hotter years, and that hotter sum-
mers had relatively higher violent crime rates than cooler sum-
mers in the same cities [22].
In sum, converging evidence from three very different
types of studies yields consistent conclusions. Being in an
uncomfortably hot environment is reliably associated with
higher levels of aggressive and violent behavior, and this ap-
pears to result mainly from heat stress–induced increases in
irritability.
Mechanisms That Underlie Direct Effects
of Temperature on Aggression
There are several major theoretical accounts of the empirical
link between heat and aggression, both psychological and
physiological, but they are not necessarily incompatible.
Possible physiological explanations rely on the fact that hot
temperatures activate the part of the brain that is responsible
for both thermoregulation and emotion regulation.
Additionally, adrenaline production increases in the heat,
which could lead to more aggressive behavior under certain
conditions (e.g., provocation). These links have been ob-
served across numerous socio-cultural areas and suggest that
this physiological connection between aggression and behav-
ior is Bhardwired^[4,11,17••,25,30].
Various theories behind psychological mechanisms also
exist to explain this relation. The psychological concept of
embodied cognition suggests that we respond to stimuli from
the environment, which influences how we think. And what
we find in the heat-aggression research is that higher temper-
atures produce discomfort, which increases aggressive
precursors such as irritability and hostile perceptions of
others [4,8]. These two types of explanations are fully com-
patible with each other. That is, there may be independent
effects of heat-induced physiological activation of emotion-
regulation parts of the brain, and of heat-induced irritability
and perceptual biases. Also, it is possible that the more social
psychological explanation (irritability, biased social percep-
tions) is the direct result of the physiological effects of heat
on emotion regulation. The compatibility of these theoretical
explanations is why we lump them together in this article as
Birritability.^
Another prominent theory is the routine activity theory
(RAT) [8,12,35]. RAT notes that people’s routine activities
are likely to differ during hot versus cool weather and that
such activities may account for some of the observed heat-
aggression effects. For example, people without effective air
conditioning in their homes may spend more time outside or
may drink more beer during hot spells, and this may influence
the likelihood of aggressive behavior. To be sure, there is
evidence that supports RAT in general, such as data showing
that weekends tend to yield higher violent crime rates than
weekdays [12,13]. However, RAT cannot account for all or
even most heat-aggression results.
Some concerns are being raised about the research behind
the link between temperature and aggression, including the
direction of and nature of the relationship between increases
in temperature and increases in aggressive behavior. However,
these concerns have been repeatedly and thoroughly ad-
dressed, and the original findings verified [11,13,25].
However, some moderators do exist when looking at the
relationship between climate and aggression. Van de Vliert
(2011) discusses the relationship between climate-based de-
mands and wealth-based resources [36,37]. Among numer-
ous findings, he reports that developing countries with de-
manding cold or hot climates are more prone to repression
of the media. Also, political riots and armed attacks do occur
more frequently in warmer countries, but these effects are
mitigated by a nation’s cultural masculinity [38].
Recently, a new model was proposed to help us understand
the mitigation of culture with the climate concerning violence.
Van Lange, Rinderu, and Bushman (2017) developed the
CLASH (Climate, Aggression, and Self-control in Humans)
model [39••]. CLASH highlights that the cultures of regions
with colder climates (especially in climates where we see great
variety in seasons) put more of a focus on the future rather
than the present, a stronger focus on self-control, and a slower
life history strategy than cultures in warmer climates. Models
and studies such as the CLASH model, and Van de Vliert’s
(2011) work, help us understand that although there is a base
level of aggression brought out by heat, this effect can be
mitigated or exaggerated by the cultural values and norms.
These direct effects of heat and underlying mechanisms
will not be the only effects of global warming on aggression.
Curr Clim Change Rep
There also are subtler, indirect effects on aggression and vio-
lence; these are discussed in the next two major sections.
Creating Violence-Prone Adults: Indirect
Effects of Climate Change on Individuals
There are two indirect ways in which rapid global warming
increases violence. Some of these effects have already begun
to emerge, especially those involved in the third major section
on group conflict effects (see Fig. 1). Central to the present
section, though, is a slower indirect effect that takes many
years to develop. Specifically, this is the idea that the likeli-
hood of a child developing into a violence-prone adult will be
increased by rapid climate change [40,41]. The theoretical
rationale is simple: known risk factors for a developing fetus
or child eventually becoming a violence-prone adult will be-
come more prevalent as a result of climate change–induced
ecological disasters. These include tropical storms and hurri-
canes, prolonged droughts, sea level rise (and consequently
the more frequent and severe flooding of coastal communi-
ties), water shortages (especially for drinking and agriculture),
and changing suitability of local agricultural practices for ef-
ficient production of food.
For example, each of the following is a known risk factor
for creating violence-prone adults: growing up in poverty,
inadequate prenatal and childhood nutrition, dysfunctional
families and parenting, disrupted families, exposure to neigh-
borhood violence, exposure to war and conflicts, low educa-
tion, and poor living conditions [22,42]. Because of space
limitations, we focus here on only four components: food
insecurity, economic deprivation, susceptibility to terrorism,
and preferential in-group treatment. In a 2015 review looking
at 28 major weather events from all seven continents, re-
searchers found that 14 of them were affected by human-
induced climate change [43]. The reader is invited to consider
how such climate change–induced ecological disasters will
increase the percentage of children who are exposed to multi-
ple known risk factors for adulthood violence.
Violence and Food Insecurity
Even in the USA, 1 in 8 households struggle to have a reliable
source of food [22]. Worldwide, the figure is much worse.
Numerous studies have shown that food insecurity, poor pre-
natal nutrition, and poor post-natal nutrition can lead to in-
creased aggressive and antisocial behavior. For example, a
study on Mauritanian children looked at their nutritional in-
take in conjunction with behavioral disorders. They found that
children who were malnourished at 3 years old were more
likely to become hyperactive and aggressive at age eight than
children who were adequately fed [44]. Three years later,
those same children were more likely to misbehave in school
and to develop symptoms of conduct disorder. These charac-
teristics, of course, are also risk factors for antisocial and vio-
lent behavior in adults.
These findings correspond with the well-known study re-
garding 100,000 Dutchmen born during and after World War
II [45]. From October of 1944, until May of 1945, a German
blockade split the western Netherlands and had severe effects
on food supplies. This study used birth records to compare
men who were malnourished during the first and second tri-
mesters of their mother’s pregnancy during the blockade, to
those born shortly after it ended and when food was more
accessible. The men whose mothers were malnourished dur-
ing their pregnancies were 250% more likely to develop anti-
social personality disorder than those whose mothers were
well fed [45].
This relation between malnourishment and antisocial ag-
gression is not a unique result [46], and one possible explana-
tion for this is the release of cortisol from the mother during
her pregnancy [47]. Other similar explanations involve the
effects of inadequate nourishment on the developing brain.
The IPCC and others have strongly warned about climate
change’s impact on the agriculture of our planet. Given this
relation between early-age malnourishment (both pre- and
post-natal) and adulthood antisocial behavior; we have reason
to expect that the climate change effects on food supply will
lead to an increased risk in violent and antisocial behavior for
individuals when they become adults [23,48,49••].
Economic Deprivation
A changing environment also presents many challenges to
current economics on a global scale. The IPCC, in both their
2007 and their 2013 reports, predicted that global warming
would indeed produce lower crop yields, poorer grazing land,
and the loss of homes due to wildfires and flooding. These
effects will be drastic and damaging but will most likely be felt
disproportionately by those in poverty and facing other eco-
nomic disadvantages [50].
We know that poverty and income disparity can lead to risk
factors for aggression (such as decreased life satisfaction, in-
creased resentment, and dissent) [51]. For those countries al-
ready facing severe economic issues, rapid climate change
will heighten the economic stressors felt by their citizens
[49••].
Perceiving inequality (whether economic, racial, class, or
even age) has also been tied to motivation for violent revenge
[52–56], and although actual poverty is not necessarily a con-
dition to foster violent behavior, research suggests that severe
economic inequality may induce violent outrage [57]. This
effect is heightened if this perception happens rapidly (such
as after a natural disaster) and if the perception leads to uneas-
iness about the individual’sfuture[58–60].
Curr Clim Change Rep
Creating Intergroup Conflict: Indirect Effects
of Climate Change on Intergroup Violence
In addition to the direct effect of heat stress and the indirect
effect of climate change on the creation of violence-prone
individuals, there is a third path to consider. Specifically, we
also must consider how larger groups and entire populations
will react to these events as well.
Ecomigration refers to group migration in response to
some physical, economic, or political instability brought
about by some ecological disaster [14••]. Although physical
displacement itself is not a direct cause of aggression, the
perceived differences between those who are relocating and
those who already live in or near the areas to which the
migrants are relocating can be a source of tension and future
violence. Combining this with other issues, such as compet-
ing for resources and infrastructure, we can see how climate
change leading to mass ecomigration can lead to mass
conflict.
The conflict in Syria is a prime example of ecomigration
and civil war brought about in part by an unprecedented
drought. Briefly (and somewhat oversimplified), the drought
forced large numbers of Syrians to migrate to Syrian cities in
search of jobs and food. The government failed to provide the
expected jobs, food, and housing, leading to political and civil
unrest, which contributed to other co-existing risk factors for
civil war. (There has been some debate over the relationship
between climate change and the violence in Syria, which we
discuss later.) Uganda has suffered a similar drought that has
also led to mass migration due to higher food prices and vio-
lence within the country. The list of similar examples includes
Kenya, Sudan, and Ethiopia. They all have climate-related
conflicts, causing scientists to believe that these types of ag-
gressive behaviors (civil wars, protests, coups, rebellions,
riots, and large-scale conflicts) will all continue to become
more frequent and more violent as the global temperature
increases [14••].
Other types of ecological disasters also can play a role in
ecomigration and subsequent increases in intergroup violence.
For example, numerous environmental issues and socioeco-
nomic factors led more than 10 million people to migrate from
Bangladesh into India. As this was happening, many Indian
citizens believed that the migrants were stealing farmland, a
cause of conflict in the region. This led to a violent outrage,
and nearly 2000 migrants were killed as a result [61].
Hurricane Katrina in the USA led to the relocation of thou-
sands of Americans, most moving to neighboring states to
seek refuge. In cities that accepted refugees (technically, in-
ternally displaced persons), homicide rates started to rise, cre-
ating a tension between residents of those cities and the refu-
gees staying there. Although these incidents never rose to
armed revolts or conflicts, this serves as another example of
the role climate change plays in violent behavior.
Terrorism
There is a rather complicated relationship between environ-
mental and social conditions in the genesis of terrorism [49••].
Factors such as losing one’s livelihood, family members, and
culture (especially when these losses can be blamed on anoth-
er group), and perceiving the losses as disproportionately af-
fecting their homes and families and their in-group, often
make people desperate and ripe for recruitment into terrorist
groups and activities. This is especially likely when the victim
feels that there is no chance of improving or mending their
situation [7,58,60]. These were motivating factors for recruits
to join militias in Sierra Leone [52,54], Palestine [53], and
Managa [14••]. Furthermore, recruits joined to regain a sense
of belonging, meaningfulness, status, power, protection, and
economic alleviation [53,54,61–67].
One study found that a single standard deviation increase
in drought intensity could increase the likelihood of inter-
group conflict in a region by as much as 62%. As noted
earlier, environmental impacts such as droughts are expected
to increase in both severity and frequency because of rapid
global warming, and they will create or exacerbate many of
the conditions that allow terrorist organizations to thrive
[16].
The economic effects resulting from climate change are
expected to be disastrous for many regions and countries,
and along with the more immediate dangers of poverty and
starvation, this research is starting to show us additional bad
societal events will occur as a result of these outcomes, events
such as terrorism and war [49••]. Children who are in regions
afflicted by wars, famine, droughts, and other harmful envi-
ronments are exposed to many risk factors for the develop-
ment of violence-prone adolescents and adults. Numerous
longitudinal studies have shown us that relatively brief expo-
sure (months or a few years) to these risk factors can put an
individual on a high-risk trajectory [22].
A study in 2002 examined the interaction between the ge-
netic alleles involved in producing monoamine oxidase A
(MAOA)—an enzymatic degrader that modulates
neurotransmitters—and maltreatment on antisocial outcomes.
The association between maltreatment and antisocial behavior
was found to be conditional on the MAOA genotype. Simply
put, 12% of the sample had the low activity MAOA genetic
risk factor and had been maltreated, but they accounted for
44% of the total convictions of violent crime. Furthermore,
85% of those who had both the genetic and environmental
risks factors developed some form of antisocial behavior.
For those who did suffer from maltreatment, the genotypic
risk factor did not manifest in behavior [67].
We understand that terrorism is caused by numerous ideo-
logical, personal, and societal factors [61]. Because of climate
change’s massive effects on resources, poverty, and economic
stressors, we can expect these conditions to be heightened and
Curr Clim Change Rep
for the risk of terrorist group formation to increase, especially
in disadvantaged countries and cultures.
Preferential In-group Treatment
Other, more Bdefensive^forms of aggression are believed to
come from climate change as well, especially in response to
resource conflicts with different racial, ethnic, and religious
groups [14••]. One study found that aggression toward out-
groups increased in response to the threat of climate change
[68].
The expected rapid changes to our planet resulting from
climate change will force interactions between various out-
groups as they are forced together due to these severe condi-
tions. As described earlier, the Syrian drought forced agrarian
groups to seek employment, shelter, and food in major cities,
which contributed to the current civil war. In addition, thou-
sands of Syrians have migrated (or are attempting to migrate)
to countries all over the world, leading to increasing political
and economic tensions and occasional acts of intergroup
violence.
What we have seen globally is a mixed response to the
refugees. Although some countries and political groups have
gone out of their way to welcome the refugees and to find
them supplies and places to live, a backlash has also occurred
in an attempt to either slow the flow of refugees into countries
or to end them altogether. The Syrian refugees (and Muslims/
Arabs generally) frequently are depicted as terrorists or rapists
in Western news and entertainment media (e.g., TV and video
games), and social media movements such as
#refugeesNOTwelcome have taken off [69•]. This rhetoric
has carried itself past the Syrian crisis, and into daily political
rhetoric. For example, research shows that exposure to such
anti-Muslim/Arab news and entertainment media increases
negative attitudes and beliefs about Muslims and predomi-
nantly Arab countries, increased support for war against those
countries, and increased support for restricting the civil rights
of Muslim-Americans [70,71•].
Syria offers us a glimpse into what the future might look
like as the climate continues to change rapidly: weather be-
comes more severe, and countries begin falling into economic
and civil distress. As people are forced to relocate, they will
also find themselves in situations much like the Syrian refu-
gees, where they are attacked as an out-group, and as re-
sources become more and more scarce, these divides may only
become stronger.
Other Perspectives
There are many critiques and questions raised when
discussing the effect of climate change on aggression.
Indeed, many factors contribute to violent behavior at the
individual level as well as at the intergroup level.
Nonetheless, it is evident that rapid global warming creates
more opportunities and situations for aggressive and violent
behavior to occur.
Another view argues that abundance causes conflict, not
scarcity [49••]. The basic premise is relatively simple—the
abundance of any given resource is a driving factor for con-
flicts, not the scarcity of a resource. Therefore, the argument
goes, many of the pathways to violence described in earlier
sections, such as scarcity offood, will not be a driving cause of
violence as a result of climate change. However, one thing to
note is that climate change will not only cause scarcity but
abundance of new resources as well. An example of this can
be found from the ice receding in the Arctic. The ice melting
away has exposed new and plentiful reserves of different min-
erals and petroleum, causing tension between countries such
as the USA, Russia, China, and Canada [62].
Another commonly expressed view is just that the climate
change’s effects on behavior are not significant enough to
increase individual aggression or to stimulate wars, so we
should ignore them. Most researchers who take this view as-
sert that differing levels of violence that have been attributed
to climate change are the result of other pre-existing risk fac-
tors, e.g., (poverty, cultural tensions, access to weapons, in-
come inequality) and not due exclusively to rapid climate
change. Stated in this rather extreme form, this is a valid cri-
tique, and for the most part, we agree. All of these factors play
significant and vital roles in increasing violent and aggressive
behavior. In some of the data examined so far, rapid climate
change may have had a relatively minor role in comparison
with other pre-existing risk factors. However, recent data and
theory strongly suggest that rapid climate change (1) has al-
ready played an essential role in violent behavior at the indi-
vidual and intergroup levels; (2) will play an increasingly
significant role in the near future as climate change effects
become more severe; and (3) climate change effects exacer-
bate other pre-existing political/social/economic risk factors
that are known to have large effects.
Other concerns about the heat hypothesis (specifically the
CLASH model) are being raised as well. Coccia (2017) sug-
gests that income inequality, latitude, and their interactions
serve as predictors of intentional homicide [72•]. Coccia
looked at 191 countries and found that even when controlling
for temperature differences, and seasonal changes, increases
in intentional homicide are positively correlated with income
inequality. However, other studies that have controlled for
income inequality have still yielded significant heat effects
on violent crime [22].
Substantial discussion over the role of anthropogenic cli-
mate change in the Syrian conflict and other current world
events has begun to take place as well. As noted by Selby
et al. (2017) [73••], the evidence for the cause of the drought
in Syria is not as straightforward as originally proposed.
Curr Clim Change Rep
Although the original authors have refuted many of these
claims [74••], the truth—as it almost always is—is quite com-
plicated. When looking at these regions for links between
climate and conflict, one must recognize that the regions are
already charged politically/environmentally, which compli-
cates the data and interpretations [75••].
We also recognize the debate over the terminology used in
this discussion [35], specifically what constitutes an environ-
mental migrant. Stavropoulou (2009) [76] argues that we
should in fact coin the term environmental refugee as it may
offer a greater sense of responsibility and urgency when
discussing who will be displaced by rapid climate change.
Even this notion has seen some resistance, Zetter (2017)
[17••] notes that Bthe label is neither sufficiently wide in scope
nor appropriate in its meaning to mobilise the range of action
and actors that are needed to address the structural and oper-
ational challenges.^
Also note, however, that despite the definitional, method-
ological, and interpretational problems that can be seen as
disagreements, there still are unifying themes. For example,
areas that are underdeveloped, economically/socially chal-
lenged, and already at risk for potential conflict will suffer
the most from these environmental changes and potential
mass migrations. There also is some consensus about what
to do. Countries with the resources to take in these migrants
or to help them relocate within their own countries should be
prepared to do so. This can mitigate the amount and severity
of the potential conflicts we will see. We also propose that the
psychological variables (out-groups vs. in-groups, the heat
hypothesis, developmental risk factors) will also play a role
in increasing the potential for conflict due to ecomigration and
that these risk factors also can be mitigated.
Warner, Dun, and Stale (2009) [77] suggested that,
BEnvironmentally induced migration occurs when ecological
tipping points are exceeded.^However, we do see some con-
cerned over the link between certain violent outcomes and
their relationship to environmental events. Freeman (2017)
[78••] noted that Bthere is a growing agreement in both the
environment-migration and climate-conflict spheres that inter-
vening variables determine if and how environmental change
causes population movements and political violence.^Our
model delineates many of these intervening variables and
processes.
In an analysis of climate-induced migrants from 1960 to
2000, some researchers found that there was no significant
effect on conflict from climate migrants [79••]. However, oth-
er research also seems clear that there must be some effect. For
example, we know that areas with water supplies see an in-
crease in violent conflicts in places where water is scarce
[80••,81••].
These kinds of complex findings are common and add a
wrinkle to what many consider is a straightforward assump-
tion of climate change ➔migration ➔increased conflict.
Many studies note that the best predictor of increased conflict
due to migration is not the migration itself, but the willingness
and preparedness of the country or region receiving the mi-
grants [79••,82].
Unfortunately, the places that are most likely to see the
most substantial amount of movement (and thus, the potential
for conflict) are the placeswhere other risk factors for violence
are already present. That is, although ecomigration itself does
not directly cause violence, it increases risk in regions that are
already at risk; if not anticipated and adequately addressed, it
likely will lead to increased violence.
Discussion
We have shown that rapid global warming increases violent
behavior via three different paths. Perhaps the most controver-
sial concerns the third path, in which extreme weather events
and more prolonged changes in food production and water
availability will force some groups of people to move, becom-
ing either refugees or internally displaced persons. In turn, this
movement increases the potential for violent behavior, espe-
cially in already-vulnerable regions. Well-tested psychologi-
cal theories of intergroup behavior, and of individual violence
(both developmental and environmental), help to reconcile
many of the differences between scholars who believe that
climate change increases migration and conflict, and those
who believe there are other mitigating factors.
Countries that are already going through intense turmoil
are particularly vulnerable to violence and conflict.
Countries with high population densities that are also
experiencing the severe loss of land, water, crops, and live-
stock are particularly susceptible to increased aggression and
violence due to rapid climate change [21,82–86].
Even countries that are economically advantaged will see
their way of life change, and their children exposed to more
risk factors for developing violent behavior. For example,
crime data from St. Louis, Missouri, found that in disadvan-
taged neighborhoods, hot temperatures saw a disproportional
rise in violent crime [87]. Moreover, although civil war seems
unlikely in currently wealthy/stable countries, conflicts and
violence due to within-country migration and between current
citizens and refugee immigrants have been documented from
past (e.g., the Dust Bowl in the USA) and recent eco-disasters
(e.g., Hurricane Katrina). So even within the most economi-
cally developed countries in the world, those who are disad-
vantaged will experience a disproportionate amount of the
harmful effects of rapid climate change on their lives [49••].
This disproportionate effect of rapid climate change between
regions, countries, or even neighborhoods will likely produce
breeding grounds for new terrorist (or gang) activity, a global
strain on available resources, and the involvement of the
Curr Clim Change Rep
developed countries in small-scale wars breaking out across
the globe [51].
Although this news seems bleak and rather grim, there is
hope, as there is a global effort among scientist and the public
to bring awareness to the severity of the issue and our ability to
revert it (even among political strife). On April 29, 2017,
marches were held across the globe in response to current
political attitudes about climate change and over 200,000 peo-
ple (in Washington D.C. alone) participated to make their
concerns heard about our planet [88•].
We already know of little things around the home that
individuals can do to help alleviate greenhouse emissions
and to reduce our carbon footprint [9] and the social sciences
can help contribute to changing public attitudes about climate
change. By using what we know about attitude change, deci-
sion-making, and behavior change, we can help educate and
encourage the general public, policymakers, and politicians
[49••]. For example, psychologists have found that framing
climate change in global phrasing, rather than using more
local and specific terms, causes people to become more peace-
ful and less aggressive when discussing and thinking about
these topics [49••]. Another study showed that getting people
to think about the legacy they would leave behind, and en-
couraging them to leave a positive one, can motivate them to
act pro-environmentally [89].
From past experience with natural disasters, we, as civi-
lized societies, should be able to prepare for future disasters
by creating policies and plans, setting aside emergency re-
sources and funds, and actively and quickly come to the aid
of refugees and internally displaced persons in humane and
conflict-reducing ways. For example, instead of inventing ex-
cuses to kick out recently successful immigrants, the USA
should be devising policies that welcome and help
ecomigrants and other refugees to become productive US res-
idents and eventual citizens. As Freeman [79••] noted, the
potential of migrants infusing into another culture and contrib-
uting new knowledge and skills is high; so, instead of fearing
migrants, we should embrace them and look to see what they
can contribute to their new homes. Future research should
look into not only how these events will play out and affect
us, but how we can proactively mitigate, or prevent, their
disastrous outcomes.
Compliance With Ethical Standards
Conflict of Interest On behalf of all authors, the corresponding author
states that there is no conflict of interest.
Human and Animal Rights and Informed Consent This article does not
contain any studies with human or animal subjects performed by any of
the authors.
Publisher’sNote Springer Nature remains neutral with regard to jurisdic-
tional claims in published maps and institutional affiliations.
References
Papers of particular interest, published recently, have been
highlighted as:
•Of importance
•• Of major importance
1. Montesquieu C. The spirit of thelaws (CohlerA, Miller B, Stone H,
Trans.). New York: Cambridge University Press. (Original work
published in 1748); 1989.
2. Anderson CA. Heat and violence. Curr Dir Psychol Sci.
2001;10(1):33–8.
3. Perry JD, Simpson ME. Violent crimes in a city: environmental
determinants. Enviorn Behav. 1987;19(1):77–90.
4. Anderson CA. Temperature and aggression: ubiquitous effects of
heat on the occurrence of human violence. Psychol Bull.
1989;106(1):4–96.
5. Raftery AE, Zimmer A, Frierson DMW, Startz R, Liu P. Less than
2 °C warming by 2100 unlikely. Nat Clim Chang. 2017;7:637–41.
6. Piguet E, Pécoud A, Guchteneire PD. Migration and climate
change: an overview. Refug Surv Q. 2011;30(3):1–23.
7. Reuveny R. Climate change-induced migration and violent conflict.
Polit Geogr. 2007;26(6):656–73.
8. Anderson CA, Bushman BJ. Human aggression. Annu Rev
Psychol. 2002;53(1):27–51.
9. DeWall CN, Anderson CA, Bushman BJ. The general aggression
model: theoretical extensions to violence. Psychol Violence.
2011;1(3):245–58.
10.•Warburton WA, Anderson CA. Aggression. In: Zeigler-Hill V,
Shackelford TK, editors. The SAGE handbook of personality and
individual differences. Thousand Oaks: Sage; 2018. p. 183–211. A
review on the psychology of human aggression.
11. Bushman BJ, Anderson CA. Is it time to pull the plug on the hostile
versus instrumental aggression dichotomy? Psychol Rev.
2001;108(1):273–9.
12. Anderson CA, Anderson KB. Temperature and aggression: para-
dox, controversy, and a (fairly) clear picture. In: Geen R,
Donnerstein E, editors. Human aggression: theories, research,
and implications for social policy. San Diego: Academic; 1998.
p. 247–98.
13. Anderson CA, Anderson KB, Dorr N, DeNeve KM, Flanagan M.
Temperature and aggression. Adv Expier Soc Psychol. 2000;32:
63–133.
14.•• Plante C, Allen JJ, Anderson CA. Likely effects of rapid climate
change on violence and conflict. In: Oglesby L, editor. The oxford
research encyclopedia of climate science. Oxford; Oxford
University Press; 2017. A comprehensive review of the psycho-
logical effects of climate change.
15. Berkowitz L. Frustration-aggression hypothesis: examination and
reformulation. Psychol Bull. 1989;106(1):59–73.
16. Maystadt JF, Ecker O. Extreme weather and civil war: does drought
fuel conflict in Somalia through livestock price shocks? Am J Agric
Econ. 2014;96(4):1157–82.
17.•• Zetter R. Why they are not refugees –climate change, environmen-
tal degradation and population displacement. Siirtolaisuus-Migr Q.
2017;1:23–8 An argument against the notion of climate-induced
migration and its potential effects.
18. Wilkowski BM, Meier BP, Robinson MD, Carter MS, Feltman R.
BHotheaded^is more than an expression: the embodied representa-
tion of anger in terms of heat. Emotion. 2009;9(4):464–77.
19. Vrij A, Van der Steen J, Koppelaar L. Aggression of police officers
as a function of temperature: an experiment with the fire arms train-
ing system. J Community Appl Soc Psychol. 1994;4(5):365–70.
Curr Clim Change Rep
20. Anderson CA, Anderson KB. Violent crime rate studies in philo-
sophical context: a destructive testing approach to heat and southern
culture of violence effects. J Personality Soc Psychol. 1996;70(4):
740–56.
21. Mares DM, Moffett KW. Climate change and interpersonal vio-
lence: a Bglobal^estimate and regional inequities. Clim Chang.
2016;135(2):297–310.
22. Anderson CA, DeLisi M. Implications of global climate change for
violence in developed and developing countries. Chapter in Forgas
JA, Kruglanski A, Williams K, editors. The Psychology of Social
Conflict and Aggression. New York: Psychology Press; 2011. p.
249–265.
23. Intergovernmental Panel on Climate Change.(IPCC). In: Parry ML,
Canziani OF, Paultikof JP, van der Linden PJ, Hanson CE, editors.
Intergovernmental panel on climate change. Cambridge:
Cambridge University Press; 2007.
24. Anderson CA, Anderson DC. Ambient temperature and violent
crime: tests of the linear and curvilinear hypotheses. J Personality
Soc Psychol. 1984;46(1):91–7.
25. Bushman BJ, Wang MC, Anderson CA. Is the curve relating tem-
perature to aggression linear or curvilinear? Assaults and tempera-
ture in Minneapolis reexamined. J Personality Soc Psychol.
2005;89(1):62–6.
26. Bushman BJ, Wang MC, Anderson CA. Is the curve relating tem-
perature to aggression linear or curvilinear? A response to Bell
(2005) and to Cohn and Rotton (2005). J Personality Soc Psychol.
2005;89(1):74–7.
27. Anderson CA, Bushman BJ, Groom RW. Hot years and serious and
deadly assault: empirical tests of the heat hypothesis. J Personality
Soc Psychol. 1997;73(6):1213–23.
28. Auliciems A, DiBartolo L. Domestic violence in a subtropical en-
vironment: police calls and weather in Brisbane. Int J Biometeorol.
1995;39(1):34–9.
29. Yasayko J. Attacks on transit drivers as a function of ambient tem-
perature. Master’s Thesis, Simon Fraser University; 2010.
30. Bulbena A, Sperry L, Garcia Ribera C, MerinoA,Mateu G, Torrens
M, et al. Impact of the summer 2003 heat wave on the activity of
two psychiatric emergency departments. Actas Esp de Psiquiatr.
2009;37(3):158–65.
31. Carlsmith JM, Anderson CA. Ambient temperature and the occur-
rence of collective violence: a new analysis. J Personality Soc
Psychol. 1979;37(3):337–44.
32. Kenrick DT, MacFarlane SW. Ambient temperature and horn
honking: a field study of the heat/aggression relation. Environ
Behav. 1986;18(2):179–91.
33. Kruglanski AW, Chen X, Deschesne M, Fishman S, Orehek E.
Fully committed: suicide bombers’motivation and the quest for
personal significance. Polit Psychol. 2009;30(3):331–57.
34. Reifman AS, Larrick RP, Fein S. Temper and temperature on the
diamond: the heat-aggression relation in Major League Baseball.
Personal Soc Psychol Bull. 1991;17(5):580–5.
35. Dun O, Gemenne F. Defining ‘environmental migration’. Forced
Migr. 2009;31:10–1.
36. Van de Vliert E. Climato-economic origins of variation in ingroup
favoritism. J Cross-Cult Psychol. 2011;42(3):494–515.
37. Van de Vliert E. Bullying the media: cultural and climato-economic
readings of press repression versus press freedom. Appl Psychol.
2011;60(3):354–76.
38. Van de Vliert E, Schwartz SH, Huismans SE, Hofstede G, Daan S.
Temperature, cultural masculinity, and domestic political violence:
a cross-national study. J Cross-Cult Psychol. 1999;30(3):291–314.
39.•• Van Lange PA, Rinderu MI, Bushman BJ. Aggressionand violence
around the world: a model of climate, aggression, and self-control
in humans (CLASH). Behav Brain Sci. 2017;40:1–63 Aresponse
to some of the concerns over the CLASH model.
40. Gottfredson MR, Hirschi T. A general theory of crime. Stanford:
Stanford University Press; 1990.
41. Moffitt TE. Adolescence-limited and life-course-persistent antiso-
cial behavior: a developmental taxonomy. Psychol Rev. 1993;100:
674–701.
42. DeLisi M. Career criminals in society. Thousand Oaks: Sage; 2005.
43. Herring SC, Hoerling MP, Kossin JP, Peterson TC, Stott PA, edi-
tors. Explaining extreme events of 2014 from a climate perspective.
Bull Am Meteorol Soc. 2015;96(12):S1–S172.
44. Liu J, Raine A, Venables PH, Mednick SA. Malnutrition at age 3
years and externalizing behavior problems at ages 8, 11, and 17
years. Am J Psychiatry. 2004;161(11):2005–13.
45. Neugebauer R, Hoek HW, Susser E. Prenatal exposure to wartime
famine and development of antisocial personality disorder in early
adulthood. J Am Med Assoc. 1999;282(5):455–62.
46. Huston AC, Bentley A. Human development in societal context.
Annu Rev Psychol. 2010;61:411–37.
47. Chen E, Cohen S, Miller GE. How low socioeconomic status af-
fects 2-year hormonal trajectories in children. Psychol Sci.
2010;21(1):31–7.
48. Intergovernmental Panel on Climate Change.(IPCC). In: Parry ML,
Canziani OF, Paultikof JP, van der Linden PJ, Hanson CE, editors.
Intergovernmental panel on climate change. Cambridge:
Cambridge University Press; 2013.
49.•• Plante C, Anderson CA. Global warming and violent behavior.
Assoc Psychol Sci. 2017. Another comprehensive review of the
psychological effects of climate change.
50. Agnew J. Waterpower: politics and the geography of water provi-
sion. Ann Assoc Am Geogr. 2011;101(3):463–76.
51. Doherty TJ, Clayton S. The psychological impacts of global climate
change. Am Psychol. 2011;66(4):265–76.
52. Archibald S, Richards P. Converts to human rights? Popular debate
about war and justice in rural Sierra Leone, Africa. J Int Afr Inst.
2002;72(3):339–67.
53. Hage G. BComes a time we are all enthusiasm^: understanding
Palestinian suicide bombers in times of exighophobia. Publ Cult.
2003;15(1):65–89.
54. Keen D. Incentives and disincentives for violence. In: Berdal M,
Malone D, editors. Greed and grievance: economic agendas and
civil wars. Boulder: Lynne Rienner; 2000. p. 19–42.
55. Reno W. War, markets, and the reconfiguration of West Africa’s
weak states. Comp Polit. 1997;29(4):493–510.
56. Stewart F. Crisis prevention: tackling horizontal inequalities. Oxf
Dev Stud. 2000;28(3):245–63.
57. Barnett J, Adger W. Climate change, human security and violent
conflict. Polit Geogr. 2007;26(6):639–55.
58. Goodhand J. Enduring disorder and persistent poverty: a review of
linkages between war and chronic poverty. World Dev. 2003;31(3):
629–46.
59. Nafziger E, Auvinen J. Economic development, inequality, war,
and state violence. World Dev. 2002;30(2):153–63.
60. Ohlsson L. Livelihood conflicts: linking poverty and environment
as causes of conflict. Stockholm: Environmental Policy Unit,
Swedish International Development Cooperation Agency; 2000.
61. Kruglanski AW, Orehek E. The role of the quest for personal sig-
nificance in motivating terrorism. Chapter in Forgas J, Kruglanski
A, Williams K, editors. The psychology of social conflict and ag-
gression. New York: Psychology Press; 2011. p. 153–166.
62. Goodell J. The pentagon & climate change: how deniers put nation-
al security at risk. New York: Rolling Stone; 2015.
63. Maclure R, Sotelo M. Youth gangs in Nicaragua: gang membership
as structured individualization. J Youth Stud. 2004;7(4):417–32.
64. Mwanasali M. The view from below. In: Berdal M, Malone D,
editors. Greed and grievance: economic agendas and civil wars.
Boulder: Lynne Rienner; 2000. p. 137–53.
Curr Clim Change Rep
65. Stewart F, Fitzgerald V. The economic and social consequences of
conflict. In: War and underdevelopment, vol. 1. Oxford: Oxford
University Press; 2000.
66. Weinstein J. Resources and the information problem in rebel re-
cruitment. Paper presented at the conference on Curbing human
rights violations by non-state armed groups. Vancouver: Centre of
International Relations, Liu Institute for Global Issues, University
of British Columbia; 2004.
67. Caspi A, McClay J, Moffitt TE, Mill J, Martin J, Craig IW, et al.
Role of genotype in the cycle of violence in maltreated children.
Science. 2002;297(5582):851–4.
68. Fritsche I, Cohrs JC, Kessler T, Bauer J. Global warming is breed-
ing social conflict: the subtle impact of climate change threat on
authoritarian tendencies. J Enviorn Psychol. 2012;32(1):1–10.
69.•Rettberg J, Gajjala R. Terrorists or cowards: negative portrayals of
male Syrianrefugees in social media. Fem Media Stud. 2016;16(1):
1This case study shows the negative reactions we see from in-
groups towards immigrants coming into their country.
70. Saleem M, Anderson CA. Arabs as terrorists: effects of stereotypes
within violent contexts on attitudes, perceptions and affect. Psychol
Violence. 2013;3(1):84–99.
71.•Saleem M, Prot S, Anderson CA, Lemieux AF. Exposure to
Muslims in media and support for public policies harming
Muslims. Commu Res. 2017;44(6):841–69 This is another excel-
lent review on how people can treat an out-group, and how the
media can change the perceptions of out-groups.
72.•Coccia M. A theory of general causes of violent crime: homicides,
income inequality and deficiencies of the heat hypothesis and of
the model of CLASH. Aggress Violent Behav. 2017;37:190–200
An excellent review and counter to the proposal of the
CLASH model.
73.•• Selby J, Dahi O, Fröhlich C, Mike H. Climate change and the
Syrian civil war revisited. Polit Geogr. 2017;60:232–44 An impor-
tant continuation about the role ofclimate change on the Syrian
conflict.
74. Kelley CP, Mohtadi S, Cane M, Seager R, Kushnir Y. Climate
change and the recent Syrian drought. Proc Natl Acad Sci.
2015;112(11):3241–6.
75.•• Hendrix CS. Searching for climate–conflict links. Nat Clim Chang.
2018;8:190–1This paper notes how other factors can impact the
conflictswe see in specific regions that are affected by migration
and climate change.
76. Stavropoulou M. Drowned in definitions? Forced Migr. 2009;31:
11–2.
77. Warner K, Dun O, Stal M. Field observations and empirical re-
search. Forced Migr. 2009;31:13–4.
78.•• Freeman L. Environmental change, migration, and conflict in
Africa: a critical examination of the interconnections. J Environ
Dev. 2017;26(4):351–74 Freeman offers excellent insight on
the intricacies and many different variables that cause conflict.
79.•• Cattaneo C, Bosetti B. Climate-induced international migration and
conflicts. CESifo Econ Stud. 2017;63(4):500–28 An excellent
analysis on climate-induced migration and conflict.
80.•• Papaioannou K. Climate shocks and conflict: evidence from co-
lonial Nigeria. Polit Geogr. 2016;50:33–47 This paper uses the
example of conflict in Nigeria to exemplify the effects of cli-
mate on conflict.
81. Salehyan I, Hendrix C. Climate shocks and political violence.
Global Environ Chang. 2014;28:239–50.
82. Hallegatte S, Bangalore M, Bonzanigo L, Fay M, Kane T, Narloch
U, et al. Shock waves: managing the impacts of climate change on
poverty. Washington, DC: Climate Change and Development
Series; 2016.
83. O’Loughlin J, Linke AM, Witmer FDW. Effects of temperature and
precipitation variability on the risk of violence in sub-Saharan
Africa. 1980-2012. Proc Natl Acad Sci. 2014;111:16712–7.
84. Raleigh C, Linke A, O’Loughlin J. Extreme temperatures and vio-
lence. Nat Clim Chang. 2014;4:76–7.
85. Raleigh C, Urdal H. Climate change, environmental degradation
and armed conflict. Polit Geogr. 2007;26(6):674–94.
86. Van de Vliert E. Climato-economic habitats support patterns of
human needs, stresses, and freedoms. Behav Brain Sci.
2013;36(5):465–521.
87. Mares D. Climate change and levels of violence in socially dis-
advantaged neighborhood groups. J Urban Health. 2013;90(4):
768–83.
88.•Page S. People’s Climate March draws 200,000 protesters as Trump
flees to coal country. In: ThinkProgress; 2017. This article shows
us the concern over climate change in the public, and the pro-
tests that surrounded that outrage last spring.
89. Zaval L, Markowitz EM, Weber EU. How will I be remembered?
Conserving the environment for the sake of one’slegacy.Psychol
Sci. 2015;26(2):231–6.
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