ScienceDaily summarizes a recent paper in the International Journal of Global Warming:
"While a strong link between environmental changes and migration is clearly visible, it needs to be considered that these environmental factors are mostly also paired with socio-economic factors like poverty and demographic changes like population growth or conflicts and institutional factors, among others," the team concludes.
One of the reasons people like Indur Goklany have been saying things like this for years:
The primary long-term solution to climate vulnerability is for all countries to adopt institutional frameworks, including decentralised government, that encourage innovation, foster enterprise and enable individuals to develop strategies and technologies to cope with changing circumstances.