DOCUMENTOS DE ECONOMIA Y
FINANZAS INTERNACIONALES
Climatic Change and Rural-Urban Migration:
The Case of Sub-Saharan Africa
Salvador Barrios
Luisito Bertinelli
Eric Strobl
January 2006
DEFI 06/01
Asociación Española de Economía y Finanzas Internacionales
http://www.fedea.es
ISSN 1696-6376
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Climatic Change and Rural-Urban Migration:
The Case of Sub-Saharan Africa
*
Salvador Barrios
European Commission
Joint Research Centre – Institute for Prospective Technological Studies
Luisito Bertinelli
CREA, Université du Luxembourg
Eric Strobl
Ecole Polytechnique, Paris
January 2006
Abstract
We investigate the role that climatic change has played in the pattern of urbanization in
sub-Saharan countries compared to the rest of the developing world. To this end we
assemble a cross-country panel data set that allows us to estimate the determinants of
urbanization. The results of our econometric analysis suggest that climatic change, as
proxied by rainfall, has acted to change urbanization in sub-Saharan Africa but not
elsewhere in the developing world. Moreover, this link has become stronger since
decolonization, which is likely due to the often simultaneous lifting of legislation
prohibiting the free internal movement of native Africans.
JEL classifications: O18, O55, Q54, R23
Keywords: urbanization, climate change, rainfall, rural-urban migration, Africa
* The views expressed by the authors are not necessarily those of the institutions they are affiliated with.
Section I: Introduction
It has been noted that historically economic development and urbanization have
tended to go hand in hand and the legitimacy of this link continues to draw considerable
attention; see, for instance, the 1999/2000 issue of the World Development Report
(World Bank, 2000). One notable exception to this stylised fact, however, has been sub-
Saharan Africa. More specifically, while sub-Saharan Africa’s rate of urbanization has
been extraordinary by international standards, growing by more than 140 per cent
between the 1960s and the 1990s - which is a rate of ten times that of OECD countries
and 2.5 times that of the rest of the developing world – it does not appear to have been
coupled with an improvement in economic wealth in this region of the world; see Fay
and Opal (2000) and World Bank (2000).
1
Furthermore, it is now a well known fact that
internal migration has been a major factor fuelling the growth of Africa’s cities. For
example, it has been estimated that rural-urban migration has accounted for roughly half
of urban growth in Africa between the 1960s and 1990s (Zachariah and Conde (1981),
Kelley (1991)), with large variations across countries. These evolutions and further
predicted increases in urbanization have consequently raised concerns about the capacity
of Africa’s urban system to absorb such massive movements of population and its
impact on sustainable development.
A natural starting point in trying to understand the lack of connection between
urbanization and development in sub-Saharan Africa is to analyse the potential
determinants of urbanization on this continent. From the general literature on what
causes urbanization, one can essentially distinguish between two groups of explanations
of rural-urban movements, which we loosely label as demand pull and supply push type.
With regard to the former, it is generally assumed that modern sectors of production,
1
Moreover, according to UN (2003) projections, sub-Saharan Africa’s urbanization should further increase
by about 3.5 per cent annually in the next 30 years.
2
which generally locate in urban areas, have higher rates of productivity and monetary
reward than the traditional rural agricultural sector and hence attract urban-rural
migrants. Supply-push explanations, in contrast, essentially refer to the possibility that
other factors directly affecting the rural sector have favoured population movements
towards cities and may not necessarily result in productivity improvements. These may
include displacement of population due to civil conflicts or other more direct
determinants of agricultural production.
One particular supply-push type factor that may have been important in
determining urbanization in Africa, and that is the focus of the current paper, is that of
climate change. In particular, long-run climate change scenarios tend to suggest that
extreme climate variations and, more specifically, water shortages, are likely to cause
abrupt changes in human settlements and urbanisation patterns in sub-Saharan Africa
more than anywhere else in the world, see Watson et al. (1998). It has also relatively
recently been noted that rainfall in Africa has, in general, been on a decline since its
relative peak in the 1960s; see, for instance, Nicholson (1994, 2001). The specific effects
of climate change on rural/urban migration in sub-Saharan Africa have, however, as of
date been poorly documented. A particularly important starting-point is that sub-Saharan
African agriculture is especially dependent on rainfall compared to most other
developing countries which triggers the potential impact of rainfall variations on
economic activity, see Barrios et al. (2003). These impacts are, in turn, especially
pronounced in rural areas where agriculture concentrate and thus potentially affect
rural/urban migration patterns. In this regard, one should note that, although climate per
se is seldom the direct root of migration, except in extreme cases like floods or droughts,
it clearly can, however, exacerbate difficult living conditions at the margin of subsistence.
3
The current paper provides empirical evidence showing that climatic change have
been an important determinant of rural-urban migration in sub-Saharan Africa. More
generally, our focus is linked to the concept of eco-refugees or environmental refugees, where
environmental conditions may influence socio-economic conditions and hence migration
(Myers, 1993).
2,
3
We specifically set out to investigate the role of the general decline in
rainfall on the African continent since the 1960s in shaping its urbanization patterns. In
this regard we take advantage of a new comprehensive cross-country data set on rainfall
and commonly used United Nations data on urbanization. Placing these in an
econometric specification of the determinants of urbanization we then explicitly test for
the impact of rainfall on urbanization in sub-Saharan Africa using other developing
countries as a natural control group. Our results show that rainfall has indeed been an
important determinant of urban growth in sub-Saharan Africa. Moreover, we find that
this effect was much stronger after decolonisation when there was less restriction on
migration in most countries.
The remainder of the paper is organised as follows. In section 2, we discuss
Africa’s rural sector’s vulnerability to shortages in rainfall. In section 3, we outline a
simple theoretical factor specific framework to demonstrate how rainfall may affect
urbanization patterns. Section 4 describes our data and provides summary statistics. Our
econometric framework and estimation results are presented in section 5. Concluding
remarks are provided in the final section.
2
The term was actually first popularised by Lester Brown of the Worldwatch Institute in the 1970s, but
perhaps the most quoted contributions on the subject are those of El-Hinnawi (1985) and Jacobson (1988).
3
Although difficult to estimate, the number of environmental refugees ranges worldwide from 10 to 25
millions (Myers, 1993).
4
