For many, the COVID-19 crisis has been an empirical demonstration of the impacts of biodiversity loss on human health. The sanitary impacts of biodiversity loss have been documented for a while, and in particular the linkages between ecosystems degradation and the proliferation of zoonotic diseases – that is, diseases transmitted from animals to humans. However, before the crisis, the focus of biodiversity loss was often on affecting primarily ecosystems, and not human societies. The health impacts of climate change are also well-documented. Every year, the annual report of The Lancet Countdown Initiative reviews these impacts, which range from cardio-vascular troubles to allergies and infectious diseases, such as dengue or malaria. The World Health Organization reckons that climate change could claim 250,000 additional lives per year between 2030 and 2050. Research has consistently shown that the arguments about the public health impacts of climate change were amongst the most persuasive, and most likely to induce behavioral changes. Yet these arguments are not often put forward in public debates on climate change, even though the COVID-19 crisis shows once again the persuasiveness of such points. For example, in France, where such evidence exists, since 2000, the two major peaks of mortality have been caused by the 2003 heat wave (made more likely due to climate change) and by the coronavirus impacts in 2020. 

Figure 1 – Excess mortality in France since 2000. The Y axis shows the total number of deaths for every day of the year. The X axis shows the progress of the year. The red curve highlights the year 2020 so far which shows a clear peak above the usual mort

Environmental changes are also among the leading drivers of migration and displacement across the world. In 2019, close to 25 million people were displaced by disasters alone, about three times the number of people displaced by conflicts and violence. At the same time that billions were forced to immobility at home, the COVID-19 pandemic also led millions to flee contaminated zones or confinement measures1, while most countries closed their borders in an attempt to slow down the spread of the virus2. And while the virus was inadvertently transported across the world by business travelers, tourists and exchange students, migrants and refugees have too often been unable to access health systems or apply distancing measures.  

Yet improving the health of migrants and reducing adverse health outcomes related to migration are also growing concerns globally. Current crises related to migration and displacement highlight the different challenges related to migrants’ health, especially in humanitarian emergencies. In recent years, many programmes and initiatives have sought to improve migrants’ health, including at IOM. During the pandemic, several governments introduced specific measures to improve migrants’ access to health services. For example, the Government of Portugal regularized irregular migrants3 allowing them to access health services, while the Government of Ireland introduced a pandemic unemployment payment4 that covered regular and irregular migrant workers alike. 

The complex relationship between environmental changes, migration and health 

Although migrants’ health and environmental migration are known to be major challenges at present, few attempts have been made to consider the complex associations that unite environmental changes, migration and health in an integrated three-pronged nexus. Therefore, we propose a basic explanatory framework that highlights the linkages between these three dimensions and seeks to encourage debate, and new research about how planetary health is concerned with, and within, this three-pronged nexus. 

Figure 2 – Explanatory framework of the relationships between environmental changes, migration and health

Environmental changes are known to affect populations’ health (pathway A; figure 2). Most of this influence is through direct exposures such as heatwaves or extreme weather events, but less direct impacts also arise from deforestation or ecosystems disruptions at large – about 75 per cent of emerging infectious diseases are zoonotic diseases. Issues such as proliferation of new or resistant strains of pathogens are also an unwelcomed scenario. The indirect impacts arising from environmental, ecological and social systems will affect human health through changes in food yields, freshwater flows and quality, stability of infectious disease patterns, air quality, social cohesion, and family income and livelihoods. These impacts are also indirect factors of migration. 

Climate change, in particular, could threaten food security through reductions in agricultural and fishery yields. This effect is particularly alarming in regions that are already facing food insecurity, such as in sub-Saharan Africa and South Asia. Moreover, the increased occurrence of flooding or drought cycles as well as hotter summers in some regions are likely to increase risks to agricultural productivity. Climate change will also impact the geographical range, seasonality, and incidence of various infectious diseases, such as malaria, diarrheal diseases, and cholera.  

Environmental changes, especially extreme weather events, deforestation, sea-level rise, soil degradation, and food and water scarcity are strongly associated with migration (pathway B; figure 2). In some cases, migration will be a strategy of last resort, with people left with no other choice as a result of loss of habitable land, extreme health risks, or deteriorating livelihoods. In this case, displacement might increase the risks of adverse health outcomes, in particular, for vulnerable groups, such as children and the elderly or the disabled, as well as those who are already suffering from (chronic) illnesses (pathway C; figure 2).  

Migration is not automatically an indicator of vulnerability; it can also be an adaptive response to cope with the effects of climate change, and not just in low-income countries. Moving to a new location might avoid the hazards from extreme weather events and degraded environmental conditions, improve health suffering from undernutrition or freshwater shortages, and eventually enhance access to health care (pathway C; figure 2). Migration, in this case, can improve human security and constitute a form of health-seeking behavior. However, as it is the case with refugees, many of the regions that receive migrants prompted to move by environmental changes are located in developing countries, where public health resources are lacking or inadequate. Thus, the health risks associated with climate-related migration are becoming a key issue and also a source of disability, morbidity, and loss of life. 

The way forward: planetary health 

Planetary health, as a new discipline, was created to safeguard human health in the Anthropocene epoch. It revolves around a new interdisciplinary and transdisciplinary approach that seeks to explore the effects of environmental change on human health. Planetary health focuses in particular on two dimensions: the first situates human health within human systems, looking at the threats faced by our species, such as pandemics or climate change; the second focuses on the natural systems within which our species evolve and looks at the health and diversity of the biosphere. 

Scholarly communities working on environmental changes, migration, and health have not yet coalesced to bring together their data, methods, and expertise. Without a framework to connect the three issues, research agendas are likely to expand in different directions and policy responses to develop in an inconsistent fashion. Planetary health demands new coalitions and partnerships across many different disciplines to meet the pervasive knowledge failures. 

Together, environmental changes and migration will have a multiplying effect on health that we should not ignore. The current COVID-19 crisis should be a wake-up call to address these three dimensions together, rather than two at a time. This approach will require the design of joint research agendas, methods, and projects across scholarly communities as well as between researchers, policy-makers and civil society at large. We contend that the concept of planetary health can prove a very welcomed instrument to achieve such connections, and inform meaningful and consistent policy responses. 

About the autors


François GEMENNE 

Dr François Gemenne leads the Hugo Observatory at the University of Liège (Belgium), a research center that works on the connections between environmental changes and migration. He lectures on these topics at the Free University of Brussels, at the University of Liège and Sciences Po in Paris. He is a lead author for IPCC (WG II) and a co-author of the Atlas of Environmental Migration with IOM. 


Anneliese DEPOUX

Dr Anneliese Depoux leads the Centre Virchow-Villermé, a French-German research center for Public Health, with a branch in Paris - Université de Paris -, and another one in Berlin - Charité Universitätsmedizin. The Centre has pioneered work on the health impacts of climate change, and is widely recognised as a European hub for research on this emerging topic. Dr Depoux founded the 4C-Health research consortium to foster this approach, and she is a member of the Lancet Countdown initiative and the Global Consortium on Climate and Health Education at Columbia University. 


Stefanie SCHÜTTE 

Dr Stefanie Schütte is an epidemiologist, working as a science and business consultant to empower researchers and innovative companies in order to achieve maximum impact in the field of health and life sciences. She is also a lecturer and course coordinator at the Apollon University for Applied Health Sciences in Germany. Prior to this, she worked as a researcher and project manager at the Centre Virchow-Villermé in Paris. 



This article is part of the IOM Series on The COVID-19 Pandemic, Migration and the Environment.

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