Planetary Health. An emerging field to be developed

The conditions for life on Earth are changing profoundly. The climate crisis is causing frequent forest fires, heat waves, floods and extreme drought. Biodiversity is rapidly declining, environmental pollution has reached every corner of Earth, nitrogen is accumulating in nature, deforestation and erosion are continuing at an alarming rate, and freshwater sources are drying up. 

If these global environmental changes continue unabated, billions of people worldwide may face serious health risks by the end of this century. Many millions may die every year in that event, and many more could suffer from heat stress, infectious diseases, malnutrition, flooding and mental disorders. Some human communities will find their very existence threatened as their habitat is flooded or scorched by heat or drought. According to the World Health Organization, climate change is ‘the single biggest health threat facing humanity’ in the 21st century.

Yet scientists are only beginning to study the impact of global environmental change on human health, and how this impact can be abated. ‘Planetary Health’ was launched as a new field in 2015 and has since grown rapidly. It is a broad field, going beyond the local environmental threats studied in the past and focusing on changes on a planetary scale.

This report presents the views of the Royal Netherlands Academy of Arts and Sciences (KNAW) on this emerging field. It identifies the main knowledge gaps and proposes a research agenda, assembled in consultation with a wide range of experts. Planetary Health as a scientific field is based on the understanding that all life on Earth is interconnected, and that safeguarding the health and survival of all species is an important moral imperative. For practical reasons, however, this report focuses mainly on human health, to which most research efforts have so far been devoted.

Scientific research shows clearly that global environmental changes are already affecting human health. More people are dying of heat stress, severe drought is causing widespread hunger, and some infectious diseases are spreading to previously uninfected areas, to mention just a few examples. While these problems are already serious ones, health impacts are expected to escalate further in the future if global environmental changes continue at their current pace.

These health impacts are the result of both direct effects, for example through heat stress or flooding, and indirect effects, for example through diminishing food yields and the spread of infectious diseases, and through migration and conflict. Such indirect effects probably affect more people than direct effects, but are much more difficult to investigate because of longer causal chains. Nevertheless, a better understanding of these indirect effects, particularly those through nutrition and infection, is essential for the development of effective countermeasures. 

Not all countries will be equally affected. High-income countries, like the Netherlands, will probably be able to manage the health effects of global environmental change in the short and medium term, although they will need to develop and implement adaptation plans, for instance to reduce the impact of heat waves or floods. Much greater health risks threaten the Global South, which is more vulnerable to these environmental changes and whose populations often lack the resources necessary for taking countermeasures. Because the prosperity of richer countries is based on their larger ecological footprint over many centuries, however, they are largely responsible for environmental changes elsewhere in the world and their health consequences.

Our knowledge of the health effects of global environmental changes varies. We know more about the health effects of climate change and the global pollution of air, water and soil than about the health effects of biodiversity loss and disruption of the nitrogen cycle. In the case of biodiversity loss, for example, empirical evidence is particularly scarce. Yet it is clear that human health depends in part on
nature’s ‘ecosystem services’, including the purification of water and air, support for food production and management of infectious diseases. These will come under increasing pressure when biodiversity declines.

Abating the causes of global environmental changes by effective ‘mitigation’ policies is crucial to preventing their health impacts. Because these changes are ultimately driven by rising human population numbers and increasing production and consumption per capita, it is worrying that both are expected to keep growing in the short and medium term. It is an open question whether technological adaptations, such as the transition to renewable energy, can turn the tide or whether more drastic changes are necessary,
such as a contraction of material production and consumption (‘degrowth’).

In either case, transformative changes will be necessary to the energy supply, transportation, industry, food production and other core sectors. For some, i.e., the transformation of the energy system, technological solutions are in sight, raising hopes that we can halt some of the global environmental changes in time. Yet policymakers, private companies, public institutions and individual citizens will need to fundamentally change their policies and behaviours to achieve these transformative changes. They will need to overcome ingrained habits, vested interests and other major barriers.

Health care also has a substantial ecological footprint, and contributes significantly to greenhouse gas emissions, pollution and other global environmental changes. Like other sectors, it will have to switch to more sustainable ways of delivering its services. In addition, health care has an important role to play in adaptation, for example when it comes to combating infectious diseases induced by climate change.

There are many knowledge gaps in the field of Planetary Health. A review of the literature and a subsequent consultation with experts have resulted in a longlist of more than one hundred specific knowledge gaps. Evidence of the human health effects of global environmental change is incomplete, pathways are insufficiently understood, the effectiveness of mitigation and adaptation policies has not yet been firmly established, and it is currently unclear how timely policy and behaviour change can be realised. 

The longlist is divided into four research areas: (A) effects of global environmental changes on human health; (B) developing effective mitigation and adaptation measures; (C) promoting the implementation of these measures; and (D) data and methods of Planetary Health research. There are important scientific challenges in each of these areas, which in most cases can only be studied through interdisciplinary research and by taking a ‘transdisciplinary’ approach that involves non-scientific partners. Many issues will also require collaboration with partners in low- and middle-income countries. Some examples of open research questions are 
given below.

Examples of open research questions in planetary health

• What is the effect of combined global environmental changes (e.g., climate change, 
  deforestation and biodiversity loss) on the spread of infectious diseases? 
• What is the environmental impact of medicines, single-use gloves and other 
  materials and equipment used in health care, and which should be prioritised for 
  replacement? 
• How does energy poverty change food choices? What incentive schemes for 
  switching to renewable energy have the largest health co-benefits and avoid a 
  widening of health inequalities? 
• What is an optimal diet for Western Europeans and other populations around the 
  world, taking into account climate change, biodiversity protection, health effects and 
  affordability? 
• How can preventive measures, for example proper ventilation, social distancing 
  and face masks, make societies more resilient to pandemics should they occur more 
  frequently as a result of global environmental change? 
• How can societies adapt to more frequent extreme weather events, sea level rise and 
  other climate change-related risks in order to avoid their health consequences? 
• How can health care professionals help their patients adopt behaviour beneficial 
  to their health and at the same time minimise greenhouse gas emissions and other 
  environmental impacts? 
• How can international environmental treaties help advance national health policies 
  so that environmental protection goes hand-in-hand with health improvement?

Experts also selected the most urgent research questions from the longlist, based on relevance to policy and the speed with which results can be achieved. Four priority areas emerged: (1) integral analyses of the effects of global environmental change on human health; (2) research guiding and supporting the transformative changes necessary to avert global environmental change; (3) research on methods for individual and collective behaviour change and governance in relation to global environmental change; (4) research guiding and supporting mitigation and adaptation strategies for the health care sector.

If climate change, biodiversity loss and other global environmental changes continue at their current pace, the foundations for human health will be seriously jeopardised. This means, first of all, that it is essential to reverse these trends. The Academy sees an important role for scientific organisations in communicating the risks of global environmental change and in advocating evidence-based solutions. The Academy also advises health care leaders to increase their involvement in sustainability debates and to help achieve the urgent societal changes necessary to avoid the health consequences of global environmental change.

Science has a key role to play in averting these health risks, not only by actively sharing available knowledge but also by filling important gaps in the knowledge base. This implies that the emerging field of Planetary Health needs to be promoted and developed. Although human health is by no means the only factor affected by climate change, biodiversity loss and other global environmental changes, it is certainly important enough to receive separate attention in research. Not only will better scientific understanding enable more effective policies, but greater awareness of the health risks of global environmental change may also help to speed up the necessary changes in the behaviour of policymakers, private companies, public institutions and individual citizens.

This report proposes an ambitious research agenda for Planetary Health. Researchers from many disciplines may find starting points here for involving themselves in this field. Adding a health dimension to studies of global environmental change, and adding a global environmental dimension to medical and health research wherever appropriate, would already be a solid first step. The Academy also recommends the creation of an interinstitutional and interdisciplinary network for Planetary Health research in the Netherlands, linked to similar international initiatives. While it is true that many universities and research institutes can contribute to this development by clearing more space for Planetary Health issues in their research portfolios, the Academy recommends in particular that the Dutch university medical centres step up their efforts in this emerging field.

Getting started in Planetary Health research will not always require new funding: existing programmes in the Netherlands already provide a few opportunities for obtaining research grants. These are inadequate, however, and the Academy therefore calls on research funders in the Netherlands to explore options for incentivising research in the face of the increasing threats to human health posed by global environmental change. For example, the four priority research areas in Planetary Health mentioned above lack proper funding options, despite being highly relevant to policy. For example, it would be very useful to create more funding opportunities for research into health care sustainability issues with a view to speeding up the transition of the health care system. If funding were conditional on
participation in an interdisciplinary and interinstitutional network, this would also catalyse the formation of a Planetary Health community in the Netherlands.

Finally, this report shows that the research agenda for Planetary Health far exceeds the scope of the Dutch research community. International cooperation will therefore be essential. Such cooperation can be promoted by bringing together national and international actors in this field, including national and international academies and research funders, to discuss the international coordination of research agendas and research funding in the field of Planetary Health.

For an integrated approach to planetary health, knowledge is needed from the medical and health sciences, from natural science disciplines such as biology and geology and from the behavioural and social sciences, to gain insight into the economic drivers of environmental change, into behavioral change and into governance issues. The humanities are needed for historical and ethical aspects, for example.  

The aim of this exploration is to create productive links between the disciplines involved and their knowledge agendas and to ensure that the need for sustainability is reflected better – or even better – in the research priorities.

The committee carried out an exploration of the scientific knowledge that is needed in the field of planetary health and identifies priorities for knowledge development in the Netherlands. 

Chair

• Johan Mackenbach, emeritus professor public health, ErasmusMC, declaration of interests (in Dutch)

Committee members

• Vera Araujo Soares, declaration of interests (in Dutch)
• Lisa Becking, declaration of interests (in Dutch)
• Frank Biermann, declaration of interests (in Dutch)
• Tatiana Filatova, declaration of interests (in Dutch)
• Ron Fouchier, declaration of interests (in Dutch)
• Louise O. Fresco, declaration of interests (in Dutch)
• Pim Martens, declaration of interests (in Dutch)
• Jan Luiten van Zanden, declaration of interests (in Dutch)

Resolution inaugurating the committee 'Planetary Health' (in Dutch)