The Bay of Bengal, the Sahel, and Small Island Developing States (SIDS) are especially vulnerable to the impacts of slow-onset climate events resulting from climate change. Global temperature warming is leading to a dramatic rise in sea levels, which will lead to coastal erosion and land loss across SIDS and the Bay of Bengal. Such warming will also contribute to increasing desertification and water scarcity issues in the Sahel. This environmental damage is irreversible and may seriously threaten economies as well as the daily lives of communities. Without strong policy interventions to bolster in-situ resiliency and increase climate change adaptation and mitigation, including migration, the regions most vulnerable to climate impacts might experience major human security and security crises. This paper provides an analysis of some of relevant regional frameworks that could be useful in addressing environmental migration across these three regions. It concludes that high-income countries such as the UK should do two things: provide financial and technical support to bolster climate adaptation in regions uniquely vulnerable to slow-onset climate events; and support the establishment and / or implementation of regional migration frameworks and free movement agreements (FMAs) that can potentially offer safe, orderly, and regular migration pathways to those affected by the impacts of slow-onset climate events.