Migration towards Bangladesh coastlines projected to increase with sea-level rise through 2100

Abstract

To date, projections of human migration induced by sea-level change (SLC) largely suggest large-scale displacement away from vulnerable coastlines. However, results from our model of Bangladesh suggest counterintuitively that people will continue to migrate toward the vulnerable coastline irrespective of the flooding amplified by future SLC under all emissions scenarios until the end of this century. We developed an empirically calibrated agent-based model of household migration decision-making that captures the multi-faceted push, pull and mooring influences on migration at a household scale. We then exposed ∼4800 000 simulated migrants to 871 scenarios of projected 21st-century coastal flooding under future emissions pathways. Our model does not predict flooding impacts great enough to drive populations away from coastlines in any of the scenarios. One reason is that while flooding does accelerate a transition from agricultural to non-agricultural income opportunities, livelihood alternatives are most abundant in coastal cities. At the same time, some coastal populations are unable to migrate, as flood losses accumulate and reduce the set of livelihood alternatives (so-called ‘trapped’ populations). However, even when we increased access to credit, a commonly-proposed policy lever for incentivizing migration in the face of climate risk, we found that the number of immobile agents actually rose. These findings imply that instead of a straightforward relationship between displacement and migration, projections need to consider the multiple constraints on, and preferences for, mobility. Our model demonstrates that decision-makers seeking to affect migration outcomes around SLC would do well to consider individual-level adaptive behaviors and motivations that evolve through time, as well as the potential for unintended behavioral responses.

Promise, premise, and reality: the case of voluntary environmental non-migration despite climate risks in coastal Bangladesh

“…Concern results also imply a harmonic and congenial living condition with cultural affinity in our study locations as no substantial political and religious conflicts, threats, and marginalization attempts were reported. These facts are also consistent with study findings by Bell et al (2021), Yonay et al (2015), and Schewel (2020).…”

Income-based Inequality in Post-disaster Migration is Lower in High Resilience Areas: Evidence from U.S. Internal Migration

“…Finally, we find that a county's level of resilience does not appear to be a serious consideration when individuals decide where they move to, which is apparent from the statistically insignificant or negative coefficient estimates on the two receiver resilience terms shown in Figure 3. This finding corroborates other studies that show individuals do not consider climate-related factors when deciding where they move to (Bell et al 2021;Hino and Burke 2021), and implies that outmigration needs to be coupled with incentives for moving to resilient areas to be a viable climate adaptation measure.…”

“…Additionally, the level of disaster resilience in an area does not appear to be an important consideration to attracting inmigration. Beyond engaging with prior evidence that suggest people do not or cannot account for the climate-related features of where they move to (Hino and Burke 2021;Bell et al 2021), which reduces the efficacy of climate migration as a climate adaptation measure, our findings show that post-disaster relocation is a driver of societal restructuring with economic (Feng, Oppenheimer and Schlenker 2012;Boustan et al 2020) and social (Molloy, Smith and Wozniak 2011;Hopkins 2012) implications.…”

Advancing the Evidence Base of Future Warming Impacts on Human Mobility in African Drylands

“…Many weather and climate‐related events have become more frequent and intense leading to widespread and disastrous impacts for populations globally (Hoegh‐Guldberg et al., 2019). In extreme cases, populations have migrated away from locations frequently impacted by extreme weather events (Gray & Mueller, 2012) or are projected to move toward coastlines affected by sea‐level rise (Bell et al., 2021). At the same time, human mobility decisions are often multi‐causal and rarely due to extreme weather events alone.…”