Intended for healthcare professionals


Climate related migration and displacement

BMJ 2022; 379 doi: (Published 12 October 2022) Cite this as: BMJ 2022;379:o2389

Read our special issue on the climate emergency

  1. Kristie L Ebi, professor1,
  2. Robert McLeman, professor2
  1. 1Center for Health and the Global Environment, University of Washington, Seattle, WA, USA
  2. 2Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON, Canada
  1. Correspondence to: K Ebi krisebi{at}

We must prepare health systems for rising numbers of people on the move

Involuntary displacement of people by climate hazards generates substantial challenges for human health and health systems in all countries and regions. Over 20 million people annually are displaced by floods, extreme storms, droughts, wildfires, and other weather related hazards.1 Climate change has already increased the frequency, intensity, and duration of some hazards, with further increases projected in coming decades.2 Rising sea levels are creating additional risks for hundreds of millions of people living in low lying coastal areas and small island states.1

With additional climate change, the number of people on the move is almost certain to rise. By how many will depend on future levels of greenhouse gas emissions, socioeconomic development trajectories (especially in low and middle income countries), and, to a lesser extent, future international migration policies.34

Most climate related migration occurs within countries, often as rural-to-urban or rural-to-rural migration.5 Not all people who experience a climate related hazard move. Those that do usually remain within their home country or, if they move internationally, go to countries within the same region. Decisions to move (or stay) and where to move to are mediated by various social, economic, cultural, and other factors that shape the options available to a given individual or household and are consequently linked to wider climate adaptation processes.67

Climate related migration is thus context specific and can range from changes in voluntary migration to sudden pulses of large scale, involuntary displacements of people fleeing hazards, which can create immediate and acute challenges for health and health systems. All forms of climate related migration will present challenges in coming decades.89

Threats to health and health systems

Climate change is increasing deaths related to heatwaves and to changes in the distribution of certain vectorborne diseases. Over coming decades, it is expected to increase the health burdens associated with waterborne and foodborne diseases, non-communicable respiratory diseases, malnutrition, mental health conditions, and injuries from extreme events.1

The magnitude and pattern of future burdens will depend on the extent of adaptation and mitigation.10 Older adults, women, children, indigenous populations, and people with pre-existing health conditions are often disproportionately vulnerable, with socioeconomic inequalities magnifying risks for such households and populations.

Migrants, particularly those involuntarily displaced, are more vulnerable than resident populations because they often have lower access to healthcare, occupy substandard housing that may lack basic sanitation, and have limited financial means and prospects. These challenges are magnified in low and middle income countries with weak health systems, although people displaced by extreme events in high income countries also face disproportionate risks, as experienced by Louisiana communities after Hurricane Katrina.1112

Health systems must manage the effects of extreme events on their staff and their ability to provide services, in addition to managing short term surges in demand from migrants and displaced people (such as treatment for injuries, cardiovascular events, and infectious diseases) and increased longer term demand for care. Increased demand caused by migration has compounding effects on other services, such as postponement of surgical or cancer treatments, with clear implications for patient health and wellbeing. The financial effects on health systems are also expected to grow.

Building resilience

Planning and investment to deal with the additional effects of climate related migration and displacement should make communities and health systems more climate resilient in general.1 Greater investment in disaster risk management, response, and prevention are pressing needs across all nations and communities. Planning and investment in healthcare must include preparations for climate related risks, and particularly for events and conditions most likely to cause involuntary displacement.

Investments in communities will also be necessary, particularly those most likely to experience surges in local demand for healthcare or inflows of migrants after climate related hazards (such as low income urban neighbourhoods that are in or near locations highly exposed to climate risks). In areas likely to receive high numbers of climate related migrants, better connections are needed between healthcare providers and services that support migrants and refugees.

Governments must ensure that all migrants have comparable access to healthcare to established residents and that they are not excluded based on residential status or citizenship. In low income countries with weak institutions, multilateral organisations and international development agencies will need to provide additional investments and commitments to build resilient food, water, and sanitation systems that enhance households’ capacity to cope with climate related disruptions. People should not be obliged to migrate involuntarily in search of food, as is happening in the Horn of Africa.1

Communities that have to be moved by governments away from high risk locations need particular attention to ensure that health and wellbeing are not compromised.13 Finally, because migrants may bring diseases and conditions not common in receiving areas—or may encounter new diseases themselves—investments in health surveillance and early detection that consider such possibilities are important priorities.14

Climate change is amplifying the drivers of migration and displacement, negatively affecting population health and putting additional strain on health systems. Additional investment is needed now to support these vulnerable populations and communities.