As we learn more about climate change, we find increasing evidence of the divergent social impact of climate-related events.

The risk of child marriage varies widely by local area among girls living in climate-vulnerable communities and depends on the nature of the climate-related events.

We explored the relationship of child marriage and climate risk assessing the environmental history of 240 communities where we study child marriage in rural Bangladesh.

We find that specific coastal communities have significantly higher child-marriage rates. There is no evidence of higher risks for child marriage in inland flood-affected areas. 

The nature of climate impact in coastal areas has been slow and cumulative, and manifests in different ways. Global warming is experienced as a result of sea-level rise, which leads to coastal flooding and salinity intrusion in communities near the coast.

The coastal district communities of Satkhira and Khulna experience annual waterlogging due to coastal flooding and seasonal tidal cycles. Saltwater that is stagnant for prolonged periods prevents the three-crop cycle that farmers are accustomed to, so now they can only cultivate one crop annually.

Years of salinity affect land quality and agriculture, fundamentally changing lives and livelihoods. Prolonged waterlogging coupled with salinity also affects access to safe drinking water, and girls are often sent far off to fetch safe drinking water. This puts girls at risk of predatory behavior by men.

Migration to urban areas nearby is the dominant adaptation strategy for families. Often, men migrate for livelihoods and women and children stay home. Entire families migrate in extreme cases. The absence of male members among those left behind or migration to a new place create additional risk and safety concerns for adolescent girls.

Child marriage is often the strategy of choice when families feel insecure. Families respond to duress in many ways, including resorting to early cessation of school and early marriage for girls, because these are the least costly short-term options.

In contrast, the weather and climate impacts of inland flooding—even when they result in short-term economic losses—are not as damaging as other climate events.

Researchers who study and compare the impact of salinity and inland flooding on migration suggest that inland flooding may not be significant because it increases land productivity. Soil scientists postulate that flood waters create rich alluvial deposits. Thus, in contrast to coastal tidal flooding and saline intrusion, inland flooding has a beneficial impact on crop production.

Our analysis shows that coastal communities that experience prolonged waterlogging and salinity have significantly higher child-marriage rates; however, there is no evidence of higher risks of child marriage in flood-affected areas.

This tells us the distinct effects and factors involved between rapid-onset events, such as floods and cyclones, and slow-onset events and less dramatically visible factors, such as waterlogging, that affect marriage through longer-term impact on lives and livelihoods.

This analysis illuminates critical differences in climate vulnerability that enable the global community to make smart investments and develop strategies and policies for individuals and communities most in need.