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Cambridge Institute for Sustainability Leadership

April 2021: With each degree of global warming, the risk of flood-induced displacement increases by 50%. Assuming a two-degree warming scenario and population growth, the average risk could increase by up to 110% by the end of the century and displace more than 1 billion people. Risk reduction measures include improved spatial and urban planning to prevent flooding and rapid action on climate change mitigation and adaptation.


Climate change has been linked to an increasing risk of temporary and permanent displacement of people around the globe. New evidence suggests that the risk of people being forced from their homes by flooding increases by half for each additional degree of global warming. With increasing frequency of severe weather events due climate change, the risk of flooding from rivers overflowing their banks increases significantly. If the population remains stable at its current level, the risk of flood-related displacement increases by more than 50% for each degree of global warming, relative to 2010 levels. In the last six months alone, 10.3 million people were displaced due to climate change, which is four times the number displaced by war conflict in the same period. For example, recent flooding events in Asia and Australia caused large populations groups to find new permanent and temporary homes. Assuming a 2-degree warming scenario and expected population growth, the globally averaged risk is projected to rise by up to 110% by the end of the century. More than 1 billion people are expected to face forced migration by 2050 due to conflict and ecological factors linked to climate change.

Implications and opportunities

Climate change has the potential to compound existing challenges such as poverty, conflict and instability. In combination with higher frequencies of severe weather events, vulnerable groups have less time to recover from one event to the next. It risks exacerbating risks to people’s physical and mental health, livelihoods, land tenancy, personal security and other aspects of wellbeing, particularly as floods disproportionately affect socio-economically vulnerable groups who live in hazard-prone areas. To address these challenges, governments could encourage flood risk management through spatial and urban planning measures as well as incentivising protective infrastructures such as dams. In addition, rapid action on climate change mitigation and adaptation is needed to reduce future risks. 


The above draw from climate, hydrology and population distribution models, and should be seen within the context of their methodological limitations.


Kam, P.M., Aznar-Siguan, G., Schewe, J., Milano, L., Ginnetti, J., Willner, S., McCaughey, J.W. and Bresch, D.N., 2021. Global warming and population change both heighten future risk of human displacement due to river floods. Environmental Research Letters16(4), p.044026.

Kappor, K., (2021). More than 10 million people displaced by climate disasters in six months, report finds. Available at: