Climate bones of contention: How climate variability influences territorial, maritime, and river interstate conflicts
| Published date | 01 January 2021 |
| Author | Bomi K Lee,Cody J Schmidt,Sara McLaughlin Mitchell |
| Date | 01 January 2021 |
| DOI | 10.1177/0022343320973738 |
| Subject Matter | Regular Articles |
Climate bones of contention: How climate
variability influences territorial, maritime,
and river interstate conflicts
Cody J Schmidt, Bomi K Lee & Sara McLaughlin Mitchell
Department of Political Science, University of Iowa
Abstract
Many scholarsexamine the relationshipbetween climate variability and intrastateconflict onset. Whileempirical findings
in thisliterature are mixed,we know less about howclimate changes increasethe risks for conflictsbetween countries.This
article studies climate variability using the issue approach to world politics. We examine whether climate variability
influencesthe onset and militarizationof interstate diplomaticconflicts and whether theseeffects are similar across issues
that involve sovereignty claims for land (territory) or water(maritime, river). We focus on two theoretical mechanisms:
scarcity (abundance)anduncertainty. We measure these concepts empirically through climate deviation (e.g.
droughts/floods, heat waves/cold spells) and climate volatility (greater short-term variance in precipitation/tem-
perature). Analyses of issue claims in the Western Hemisphere and Europe (1901–2001) show that greater devia-
tions and volatility in climate conditions increase risks for new diplomatic conflicts and militarization of ongoing
issues and that climate change acts as a trigger for revisionist states.
Keywords
climate, conflict, maritime, river, territory
A 2014 report from the Intergovernmental Panel on Cli-
mate Change(IPCC) identifies avariety of climate changes
that will continue in the next century, such as increases in
land and ocean surface temperatures and weather and
climate related disasters.
1
Climate change will affect the
quantity andvariability of available freshwater, agricultural
productivity,the frequency of naturaldisasters, coastal ero-
sion, theseasonality of water run-off,land degradation, and
countries’territorial and water borders(Hendrix & Glaser,
2007; Busby, 2008; Bauer, 2011; Bernauer & Siegfried,
2012).
2
These environmental shocks pose many risks to
human and state security by increasing water scarcity, cre-
ating more environmental migrantsand refugees, harming
economic productivity, and raising risks for intrastate and
interstate conflicts. While many scholarly studies examine
the relationship between naturaldisasters, climate changes,
and intrastate violence (Burkeet al., 2009; Buhaug, 2010),
we know less aboutthe connections between climatevaria-
bility and interstate conflicts over land andwater resources.
Most interstate conflict research on this topic focuses on
how climatechange affects militarized interstatedisputes in
general (Stalley,2003; Gartzke, 2012)or how shared water
resources influence the risks for interstate conflict (Toset,
Gleditsch & Hegre, 2000; Hensel, Mitchell & Sowers,
2006; Brochmann & Hensel, 2009; Brochmann & Gle-
ditsch, 2012; Devlin & Hendrix, 2014).
However, climate variability can be connected more
explicitly to diplomatic issue claims involving territorial,
Corresponding author:
sara-mitchell@uiowa.edu
1
See ‘Climate change 2014: Impacts, adaptation, and vulnerability’;
https://www.ipcc.ch/report/ar5/wg2/.
2
Climate changeinvolves long term changes in ‘meanconditions’, such
as increases in globaltemperatures, changes in annual precipitation, or
risingsea levels, as well as changesin the intensity or frequencyof natural
disasters (Barnett & Adger, 2007: 640). Climate variability (Theisen,
2017; Koubi, 2019)captures short-term deviationsof weather patterns
from their long-run means, with larger valuesindicating larger shocks
(e.g. floods, droughts, heat waves).
Journal of Peace Research
2021, Vol. 58(1) 132–150
ªThe Author(s) 2021
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DOI: 10.1177/0022343320973738
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maritime, and river areas given that the effects of climate
shocks influence the salience and uncertainty of resource
control for contested issues (e.g. water quantity/quality,
fisheries stocks, agricultural viability of land). Issue scho-
lars show that diplomatic issues higher in salience are
more likely to experience militarized disputes and inter-
state wars (Hensel et al., 2008), although the effects of
climate variability have been mostly ignored in this lit-
erature. This study considers whether climate variability
in weather patterns influences interstate conflict using
data from the Issue Correlates of War (ICOW) Project
(Hensel et al., 2008; Hensel & Mitchell, 2017).
3
We examine whether climate variability influences the
onset and militarization of interstate diplomatic conflicts
and whether those effects are similar across issues that
involve sovereignty claims for land (territory) or water
(maritime, river).
4
We focus on two theoretical mechan-
isms – scarcity (abundance)anduncertainty –andwe
measure these concepts empirically through climate
deviation (e.g. droughts/floods, heat waves/cold spells)
and climate volatility (greater short-term variance in pre-
cipitation/temperature). We start with a set of dyads that
could experience diplomatic conflicts (politically relevant
dyads) and determine if deviations and volatility in cli-
mate variables increase the propensity for new diplo-
matic conflicts over land or water issues. For issue
claims that occur, we also determine if precipitation and
temperature deviations alter states’ foreign policy deci-
sions to militarize claims.
The topic is highly relevant because climate variability
has increased over time. Figures 1a and 1b present sys-
temic changes in climate conditions between 1901 and
2016.
5
We see that average temperatures and precipita-
tion levels have increased, especially since 1960, and that
countries are experiencing larger deviations from their
long-run means in more recent decades, especially for
temperature. While scholars have shown that long-run
increases in global temperatures may be associated with
fewer interstate conflicts, especially in the pre-industrial
period (Zhang et al., 2007; Tol & Wagner, 2010;
Gartzke, 2012), we have less evidence about how climate
variability influences conflict dynamics at a local, dyadic
level. We illustrate our theoretical logic with diplomatic
conflicts between Bolivia and Chile over the Mauri and
Lauca rivers, showing that diplomatic and militarized
interactions increased when these states experienced
greater deviations from long-term precipitation means.
More generally, our analyses of issue claims in the
Western Hemisphere and Europe show that greater
deviations and volatility in climate conditions increase
risks for new diplomatic conflicts and that the risks of
conflict are greatest for revisionist states. Our study
makes several contributions to the existing literature on
climate variability and conflict. First, we go beyond pre-
vious interstate conflict studies that focus on higher lev-
els of military engagement by also considering how
diplomatic interactions at lower levels of hostility are
influenced by climate variability. Second, our connec-
tion of climate issues and the issue approach to world
politics allows us to think about scarcity and uncertainty
through a new theoretical lens. Third, we show how
precipitation and temperature deviations influence dip-
lomatic issues collectively or separately. While the river
literature considers climate conditions, our results sug-
gest climate variability influences territorial and maritime
issues also. Given that territorial issues are the most esca-
latory of all diplomatic issues, this is a potential concern
for states’ future security. Finally, by looking at challen-
ger and target states in diplomatic exchanges more care-
fully, our study helps us understand whether climate
variables are factors that push states into revisionist posi-
tions and whether challengers are more strongly affected
by climate changes than targets.
Literature review
Conflict scholars examine how climate change and cli-
mate variability influence the risks for interstate and
intrastate wars.
6
Global warming over the past few cen-
turies has been associated with the decline of interstate
warfare, reflecting the economic efficiencies that globa-
lization creates relative to territorial conquest (Zhang
et al., 2007; Tol & Wagner, 2010; Gartzke, 2012).
On the other hand, long-term changes in population
and natural resources can spark interstate conflict as pre-
dicted by lateral pressure theorists (Choucri & North,
1975). Dyadic studies show enhanced interstate conflict
3
For information about the ICOW project, see http://
www.paulhensel.org/icow.html.
4
The ICOW project has also collected data on identity claims, which
could be affected differently by climate variability because they are
high on intangible salience but low on tangible salience (Hensel &
Mitchell, 2017).
5
This time series aggregates states’ data on precipitation and
temperatures collected by the Climate Research Unit at the
University of East Anglia (2019).
6
For reviews of this literature, see Barnett & Adger, 2007; Nordås &
Gleditsch, 2007; Sale hyan, 2008; Theisen, Gleditsch & Buhaug,
2013; Burke, Hsiang & Miguel, 2015; Sakaguchi, Varughese &
Auld, 2017; Theisen, 2017; Koubi, 2019.
Schmidt et al. 133
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