Ravenstein was one of the first systematic observers of migration patterns (he also used census and statistical sources). Even today, many of his observations (as opposed to ‘laws’, obviously most all of them can be disproved) have a ring of truth. As McLeman and Gemenne point out, a small percentage of migrants actually make their way to either Western Europe or North America. Countries hosting at least one million refugees, for instance, include Uganda, Lebanon, Jordan, and Iran. Turkey hosts nearly three million. Kenya hosts nearly a million, and has one of the largest refugee camps in the world. (from Somalia, South Sudan, and Democratic Republic of Congo, or DRC). Many refugees are fleeing violence, which could be civil war, it could be state-sponsored violence, or violent organized crime. Of course many of those are also hoping to find economic opportunity in a new home–a strong ‘pull’ factor–but the ‘push’ of violence is often present. Increasingly catastrophic events related to weather and climate are leading to displacement (when they are ‘rapid-onset’ especially) or migration of varying duration, when they are slower-onset, such as drought, desertification, coastal erosion, aquifer depletion, etc. From page 31 in Adger et al. (in McLeman and Gemenne):

 

Vulnerability is one way to think about migration and mobility. The authors refer to it as ‘the degree to which a system is unable to cope with the adverse effects of environmental change.’ They relate it to a function of exposure (to for instance extreme weather events or slower-onset ones), sensitivity (how resilient or able to respond to change is the environment, or a given population?), and adaptive capacity (do people possess the knowledge and resources to respond to change in ways that lessens risk to social groups and livelihoods? Depends on the scale and scope of an event or longer-term trend). The authors suggest an inverse relationship between vulnerability and mobility. For instance, when levees broke and parts of New Orleans were flooded during the aftermath of Hurricane Katrina in 2005, it was the people who lacked means who were stuck, and the response from FEMA and the federal government was a spectacular failure. Many people never returned to New Orleans–it also takes money and resources to rebuild, and were subject to the vagaries of the real estate market and rising rents. In the US and elsewhere, there is no guarantee that migrants will be welcomed, and in fact the more common experience may be racism, discrimination, and hostility (example from the Black Diaspora from the South in the US in the 1950s**). Some cities are also poorly-equipped with infrastructure to accept large numbers of migrants. 

The authors do point out that migration can lead to greater resilience. For instance, migration can reduce population pressure from the point of origin. Additionally, migrants, once settled, may find employment and be able to send remittances back to family members. 

Though expensive, ‘managed retreat‘ has been undertaken by some governments, a few places in the US in Bangladesh–where millions essentially live in and around a massive river delta in the capital of Dhaka–and on the island of Fiji, for instance. 

 

*Robert McLeman and Francois Gemenne (editors). 2018. Routledge Handbook of Environmental Displacement and Migration. London: Routledge (pg 6).

**Frances Fox Piven and Richard Cloward. 1993. Regulating the Poor. NY: Vintage