CHAPTER 5 CLIMATE CHANGE AND MIGRATION| 63
environmental change and migration is not directly evident: the causality connection manifests itself through
a series of channels, through the loss of agricultural productivity (Cai et al. 2016; S. Feng, Krueger, and
Oppenheimer 2010; Shuaizhang Feng, Oppenheimer, and Schlenker 2012), economic capital, income and
wage losses (Cattaneo and Peri 2016; Dell, Jones, and Olken 2012; Hsiang 2010; Marchiori, Maystadt, and
Schumacher 2012), increasing agricultural prices, and stressed ecosystems (Kumari Rigaud et al. 2018).
In this context, environmental change can be seen as a driver per se, but one that intersects with other drivers
of migration at some time. Furthermore, it is even a factor able to modify the other drivers and introduce
constraints to migratory flows. Another channel by which climate change could cause human migration is
represented by its controversial role in exacerbating or igniting civil conflicts (Almer, Laurent-Lucchetti, and
Oechslin 2017; Hsiang, Burke, and Miguel 2013; Missirian and Schlenker 2017). Finally, changing
environmental conditions, jointly with unsustainable or unethical economic exploitation of natural resources,
could also determine the loss of human habitat (Sassen 2016).
Heterogeneous response to homogeneous changes
Human responses to different environmental changes reflect the magnitude, intensity, geographical
distribution, and persistence over time of the particular natural hazard faced at the time. Historical
observation, however, has documented that even in the case of the same type of natural hazard, different
communities, characterised by different socio-economic and cultural conditions, react in different ways. Due
to the limited availability of viable options, low income populations adopt different strategies compared to
middle income ones. Even within the same communities, peoples' decisions to migrate are heterogeneous
due to household or personal characteristics: age, gender, marital status, education, income, occupation
(Mastrorillo et al. 2016).
The heterogeneity of the response to climate induced stressors on the human environment is likely to be
connected to the degree of vulnerability of the population exposed to the environmental or climate related
hazard, its resilience to the shocks, and its capacity to cope with the changing conditions (IPCC 2014). High
income countries, as well as higher income communities within other countries, are usually characterised by
more resilient infrastructural and institutional apparatuses and more social, political and economic capital.
On the one hand, this mitigates the impacts of climate induced change on the population. On the other hand,
it enables those people to be more effective in coping with fast and slow on-set climate events (Gizelis and
Wooden 2010). In contrast, the impacts of climate induced economic losses on vulnerable populations
deprive communities of the economic means that would be necessary to afford the transaction cost of
migration. In other words, the impacts of climate change on vulnerable populations, especially from rural
areas in low income countries that are extremely dependent on agriculture, result in the loss of the possibility
to consider migration as an adaptation option (Foresight 2011).
Quantifying the degree of social vulnerability is not an easy task (Cutter 1996; Cutter, Boruff, and Shirley
2003). While an overview about the existing indices is provided in Neher and Miola (Neher and Miola 2016)
and Miola et al. (Miola et al. 2015), there is no unanimous consensus about the specific components of social
vulnerability, which is a multidimensional concept structured to consider the factors allowing communities
to cope with and recover from environmental hazards. Summarising the findings presented in the literature,
the most important determinants of social vulnerability are mainly related to: socioeconomic status in terms
of employment, income, political power and position in relation to the social structure, income inequalities,
poverty, social dependence; demographic factors as gender, race and ethnicity, age, household and family
structure, education; population dynamics and growth; socio-environmental characteristics as living in rural