Climatic Factors as Determinants of International Migration

AuthorMichel Beine, Christopher Parsons
Publication Date01 Apr 2015
Scand. J. of Economics 117(2), 723–767, 2015
DOI: 10.1111/sjoe.12098
Climatic Factors as Determinants of
International Migration
Michel Beine
CREA, University of Luxembourg, L-1511 Luxembourg
Christopher Parsons
International Migration Institute, University of Oxford, OX1 3TB, UK
We examine natural disasters and long-run climatic factors as potential determinants of
international migration, implementing a panel dataset of bilateral migration flows from 1960
to 2000. We find no direct effect of long-run climatic factors on international migration
across our entire sample. These results are robust when conditioning on origin-country
characteristics, when considering migrants returning home, and when accounting for the
potential endogeneity of migrant networks. Rather, we find evidence of indirect effects of
environmental factors operating through wages. We find that epidemics and miscellaneous
incidents spur international migration, and there is strong evidence that natural disasters
beget greater flows of migrants to urban environs.
Keywords: Environmental change; natural disasters; utility maximization
JEL classification:F22; O15
I. Introduction
Climate change remains at the vanguard of the international development
policy debate. In The Stern Review, while analyzing the economic impact
This paper was commissioned under the auspices of the Foresight Global Environmental
Migration project and the authors gratefully acknowledge funding from the UK Government
Department for Business, Innovation and Skills. The authors are indebted to Tim Osborn for
providing the environmental data and to Simon Gosling who went beyond the call of duty
to facilitate their use at short notice. Gratitude also needs to be extended to the members of
the Determinants of International Migration (DEMIG) project, based at the International Mi-
gration Institute at the University of Oxford, which received funding from the European Re-
search Council under the European Community’s Seventh Framework Programme (FP7/2007-
2013)/ERC Grant Agreement 240940 (see,
for allowing privileged access to their bilateral visa data. The authors also wish to thank
the editor, the Lead Expert Group of the Foresight Global Environmental Migration project,
especially Stefan Dercon, in addition to C´
ecile Couharde, Richard Disney, Fr´
eric Docquier,
Markus Eberhardt, Giovanni Facchini, Katrin Millock, Richard Upward, and L. Alan Winters
for useful and timely comments.
CThe editors of The Scandinavian Journal of Economics 2014.
724 Climatic factors as determinants of international migration
of climate change, Stern (2007) emphasized the global consequences of in-
action, the need for a coordinated international response, and the fact that
developing countries will likely suffer disproportionately. This final point
was also stressed in the first United Nations (UN) intergovernmental report
on climate change, which further stated that “the gravest effects of climate
change may be those on human migration as millions will be displaced”
(International Panel on Climate Change, 1990). Myers (1996) counted some
25 million environmental refugees in 1995, and forecast some 200 million
by 2050 (Myers, 2002). Although the term “environmental migrant” is
perhaps not a useful distinction to make (Castles, 2002), these estimates
nevertheless highlight the magnitude of possible future movements that
might, at least in part, be driven by environmental change. Despite these
dire predictions, surprisingly few papers examine either the direct or indi-
rect effects of environmental factors on international migration.
This paper contributes to the literature by examining, for the first time,
the overall (macroeconomic) impact of the effects of climate change on
international migration using a panel of global bilateral migration flows.
Our key finding, once we have controlled for other leading drivers of
international migration (i.e., economic, cultural, political, social, and de-
mographic factors) is that we uncover no evidence of long-run climatic
factors directly affecting international migration. Conversely, our results
suggest that long-run climatic factors might affect international migration
indirectly, and we argue that at least one plausible mechanism is via wage
differentials. Although for some counterintuitive, this conclusion is in line
with much of the recent literature on the subject, as shown, for example,
by the following.
Environmental Change will affect migration now and in the future, specifi-
cally through its influence on a range of economic, social and political drivers
which themselves affect migration. However, the range and complexity of the
interactions between these drivers mean that it will rarely be possible to dis-
tinguish individuals for whom environmental factors are the sole driver. (UK
Government Office for Science, 2011)
Conversely, we find that epidemics and miscellaneous incidents spur
international migration, and we uncover evidence that natural disasters beget
greater flows of migrants to urban environs.
Climatic factors manifest in many guises and might impinge upon mi-
gration in myriad ways. These include extreme weather phenomena and
variability in temperature and precipitation (Boko et al., 2007). Marchiori
et al. (2011) advocate two channels (one direct and the other indirect),
via which these types of climatic factors beget international migration.
Most obviously, climatic factors have the greatest impact upon countries
that rely more heavily upon agricultural activities (Mendelsohn and Dinar,
CThe editors of The Scandinavian Journal of Economics 2014.
M. Beine and C. Parsons 725
1999), which in turn might encourage international migration directly. Most
likely, in such contexts, climatic factors will result in greater urbaniza-
tion, the increased pressures from which might foster greater incentives to
migrate abroad. However, rural–urban migration might also indirectly lead
to international migration, because increased rural–urban migration results
in downward pressure on urban wages, thus creating greater incentives for
emigration. Less obviously, climatic factors might also directly result in
international migration because of a change of amenities or because of
changes in non-market costs, such as a higher incidence of disease (Patz
et al., 1996). In either case, the effects of climatic factors likely most affect
the rural poor in developing countries, exactly those who are least able to
self-insure or to adopt alternative coping strategies.
Piguet et al. (2011) emphasize two main, interconnected, arguments con-
cerning the climate change–migration nexus. Their first argument pertains
to the fact that the identification of environmental factors as the sole cause
of migration might never prove possible, because complex interactions ex-
ist between climatic change and other categories of deterministic factors:
economic, social (and/or cultural), political, and demographic. Therefore,
societies already vulnerable in some sense will likely be disproportion-
ately challenged, with the rural poor arguably affected the most. Dell et al.
(2012), for example, show that a rise in temperature of one degree in a
given year translates into a reduction of annual economic growth of 1.1 per-
cent points in poor countries (but has negligible effects in rich countries).
They also show that the effects of higher temperatures have widespread
effects, including reductions in agricultural productivity, industrial output,
and investment. Furthermore, Dell et al. (2009) show that similar rises in
temperature result in reductions in per capita GDP both across and within
countries and within states. Their theoretical model predicts that approxi-
mately half of these reductions in income might be mitigated by adapting
to the environment, through migration, changes in fertility rates, and mor-
tality. Barrios et al. (2010) provide evidence that sub-Saharan Africa would
have reduced the gap in per capita GDP (by between 15 and 40 percent)
compared with the rest of the developing world, were no decline in rain-
fall to have occurred in this region after 1960. Because climatic variations
affect individuals’ incentives to migrate and also their ability to do so, it
proves impossible to disentangle migrants’ primary motivations to migrate,
whether it be forced or voluntary (i.e., separating economic incentives from
environmental push factors). At the macroeconomic level, the best we can
do is to assess the relative direct impact of climatic factors on international
migration, having accounted for other classes of determinants. Macro-
economic studies that examine climatic factors often suffer from selection
biases, because unobservable country characteristics are difficult to control
for (Lilleør and Van de Broeck, 2011), so the inclusion of all main classes
CThe editors of The Scandinavian Journal of Economics 2014.

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