In what ways might the concept of ‘planetary health’ lead us to think differently about contemporary global challenges? How could the resulting insights promote the changing of current practices?

“What is the use of a house if you haven’t got a tolerable planet to put it on?”

- Henry David Thoreau

In a world characterized by complexity and uncertainty, the need for a comprehensive understanding of our planet’s health has become abundantly clear. The concept of planetary health stands out as a critical lens for examining the impact of human actions on the Earth’s ecosystems and, in turn, on human health itself. Firstly, this essay will discuss the definition of planetary health and elucidate how human activities have led to unprecedented environmental changes, highlighting the importance of recognizing and addressing these impacts. Subsequently, it will assess the various ways in which these environmental changes directly and indirectly affect human health. It will then discuss ethical and philosophical considerations from a planetary health perspective. Lastly, this essay will explore potential avenues and strategies for mitigating these impacts, promoting a shift towards sustainability that aligns with the principles of planetary health.

What is planetary health?

Fundamentally, planetary health can be defined as ‘the health of human civilisation and the state of the natural systems on which it depends’ (Horton et al. 2014). Planetary health represents a paradigm shift in understanding the impact of humanity’s environmental footprint on human health and well-being, and can be viewed as an expansion of the public and global health spheres. Public health traditionally concentrates on health issues within specific populations, employing preventative measures and interventions to safeguard and improve health outcomes, whilst global health extends this scope to consider health issues that transcend national borders (Beaglehole and Bonita 2010; Gatseva and Mariana 2011). However, whilst addressing key aspects of health, both fields have long overlooked the profound implications of human activity on environmental degradation and ensuing human health. The field of planetary health investigates the connections between anthropogenic activities, environmental changes and resultant impacts on human health (Myers and Frumkin 2020). For example, climate change continues to be labelled as the most significant threat to human health globally, yet it is predominantly driven by the abundant release of greenhouse gases by humans (Romanello et al. 2023). Furthermore, the ‘triple planetary crisis’ of climate change, pollution, and biodiversity loss have been shown to interact in complex ways that threaten human health (UN Climate Change 2022). Planetary health acknowledges the reality that human behaviours and systems can no longer be addressed separately from environmental factors, given that humanity has emerged as a major driving force shaping the biophysical state of the Earth and thereby directly influencing such factors (Whitmee et al. 2015). In essence, what were previously viewed as distinct determinants of health are in fact deeply interconnected, and therefore necessitate an integrated approach to manage.

Central to the concept of planetary health are planetary boundaries, a framework that identifies nine critical thresholds in Earth’s biophysical systems (which include climate change, biosphere integrity, land-system change, freshwater use, biogeochemical flows, ocean acidification, atmospheric aerosol loading, stratospheric ozone depletion, and novel entities or ‘chemical pollution’) beyond which the stability and resilience of these systems, and consequently the well-being of human societies, may be compromised (Stockholm Resilience Centre 2023). The notion of ‘tipping points’, where biophysical systems may undergo rapid, non-linear change once certain thresholds have been surpassed, present dire risks to humanity (Barnosky et al. 2012; Steffen et al. 2015). Perhaps most daunting is the scientific consensus that such changes may be irreversible (Richardson et al. 2023). The status quo, characterized by the transgression of six out of nine planetary boundaries, poses an unprecedented threat to human health and the planet’s ability to support life (Richardson et al. 2023).

There are numerous ways in which planetary health can help us to perceive current global challenges differently, as will be discussed below.

Interconnected variables

Planetary health research reveals how the health effects of humanity’s environmental footprint are far more extensive than were previously imagined, such as the implication of human-driven ecological changes in the spread of infectious disease. According to Myers and Patz (2009), the combined effects of river damming and eutrophication from fertilizer use can increase populations of schistosomiasis vectors. Furthermore, climate-related shifts in temperature and precipitation favour the proliferation of mosquitoes, elevating the risk of malaria, dengue and other vector-borne diseases in endemic regions (Brown, Medlock, and Murray 2014). The prevalence of plastic waste has also been shown to contribute to the spread of dengue-carrying mosquitoes in sub-Saharan Africa, exacerbating the problem (Veidis et al. 2022). Such phenomena may occur against the backdrop of deforestation and land-system change, which have been shown to facilitate the transmission of zoonotic diseases such as the Ebola virus (Whitmee et al. 2015). The emergence of the SARS-CoV-2 virus, which resulted in the COVID-19 pandemic, has also been linked to biodiversity loss (Lawler et al. 2021).

Additionally, the abundance of road dust and associated pollutants may act as transport vectors for pathogenic viruses including SARS-CoV-2, increasing the spread of infectious disease (Alex et al. 2023). Recent events, such as the COVID-19 pandemic, have exposed the vulnerability of the global economic and health systems to infectious diseases outbreaks (Naseer et al. 2023). A worsening planetary health crisis may increase the risk of these systems collapsing. Research has also revealed the effects of air pollution on non-communicable diseases (NCDs). A recent review has linked air pollution with an increased risk of NCDs at all levels of life, such as male infertility, impaired foetal development during pregnancy, and cognitive impairment during adolescence (Fuller, Friedman, and Mudway 2023). Undernutrition may also be aggravated by pollution. Myers et al. (2014) estimate that increasing levels of atmospheric carbon dioxide will put millions of people at risk of micronutrient deficiencies secondary to reduced crop nutrient profiles.

Furthermore, food and water scarcity have been shown to result from the concurrence of drought, arable land degradation and loss of pollinator species (Whitmee et al. 2015). Faced with dire circumstances, vulnerable populations may resort to large-scale migration, the beginnings of which we have already observed in communities fleeing the effects of desertification in the Sahel (British Red Cross n.d.). Historical analysis has shown uncontrolled migration to be associated with numerous risks, such as the outbreak of conflict over land and resources which can result in immense human suffering including famine, physical trauma and loss of life (Abel et al. 2019). Furthermore, the collapse of local health systems during such conflicts is likely to worsen health outcomes further. It is also worth mentioning that such conflicts have the propensity to grow into regional wars (Howard 2018). If involving nuclear armed states, the consequences could be devastating.

The risk of declining mental health is often devoid from discourse on health and the environment. Links between poor physical health, especially NCDs, and worsening mental health have been well established (Ohrnberger, Fichera, and Sutton 2017). ‘Solastalgia’, which refers to distress caused by environmental change, may become more prevalent in areas projected to be most affected by climate change, such as Pacific Islanders who face the prospect of their homes submerging under rising sea levels (Albrecht et al. 2007; Thomas et al. 2020). It is also worth emphasizing how little we know about the health impacts of microplastics and domestic chemicals, of which research is ongoing (Ali et al. 2024; US EPA 2023).

A robust moral imperative

Developed countries, which have historically contributed the most to the environmental crisis, have placed a disproportionate burden on the planet’s ecosystems (Rockström et al. 2009). Unfortunately, it is the poorest nations who are poised to suffer the most from the impending planetary health crisis, highlighting a stark inequality in the impacts and costs of global environmental changes (IPCC 2014). This raises a question for us as individuals – If we claim to uphold sound ethical principles, how can we continue to persist in the mindsets, actions and systems that are not only harming ourselves, but impacting the poorest and least responsible populations most? Are we truly balancing the duty of care we have towards ourselves and others? As a society, by not prioritizing sustainability and altering lifestyles that directly contribute to the planetary health crisis, are we truly upholding the ethical pillar of justice? As research continues to reveal the deleterious health effects of humanity’s ecological footprint, this imperative becomes difficult to deny.

Recognising our shortcomings

The question arises – How did we find ourselves in this predicament? Perhaps the issue lies not within science itself, but in the persistent inclination towards a version of scientism stripped of essential values like moderation, humility, and caution, whilst dismissing alternative viewpoints that align with planetary health, such as indigenous and faith-based traditions. Whilst the advancement of science has undeniably brought significant benefits to human civilization, an unprecedented cost has been incurred in the process. The flaws and failures of neoliberal ideology, consumerism and materialism, which have led to the deterioration of Earth’s biophysical conditions, signal an imminent need for us to rethink the philosophical foundations of our global systems.

Whilst formidable, the insights derived from a planetary health perspective will fall short without the ability to be transformed into practical actions, which will be discussed next.

Inducing grassroots-level change

Contemporary media coverage on climate change and the wider environmental crisis has been dominated by vague rhetoric of uncertainty and the selective reporting of issues such as extreme weather events (Perga et al. 2023). Although public awareness on issues such as climate change are high, significant disparities exist in the perceptions of associated health impacts (Ejaz, Mukherjee, and Fletcher 2023). For example, a multinational survey by Van Wijk et al. revealed low levels of public knowledge on the role of climate change in the spread of infectious diseases (Van Wijk et al. 2020). This indicates that there is a deficit in the distribution of planetary health research findings amongst the public.

Change must begin by propagating a truthful sense of the imminence of a planetary health crisis and disseminating information to the public on the actions and risks associated with declining planetary health. Information must also be paired with empowering messages to counter sentiments of defeatism (Heyd 2011). It must be noted that people are more likely to change by conforming to social norms than through information alone (Bergquist et al. 2023). Therefore, by working with public figures and influencers to showcase examples of sound planetary health behaviours, enough social pressure can be established to invoke this avenue of change. Furthermore, sharing practical advice for making change, such as writing to politicians and boycotting goods from unsustainable companies, can also be helpful in challenging the entrenched systems and interest groups that perpetuate the status quo (Roser-Renouf et al. 2016). Customizing messages to resonate with distinct demographics can significantly enhance their effectiveness. For instance, urban residents in Texas might respond more positively to information about the detrimental effects of urban heat islands and residential carbon emissions (Yang et al. 2016). In contrast, farmers in Belize could gain more from understanding the adverse health consequences of excessive fertilizer use (Whitmee et al. 2015). Additionally, engaging with indigenous communities and various religious groups to champion planetary health introduces a unique opportunity for behavioural change. By exchanging insights and identifying how planetary health principles integrate with their belief systems, broader acceptance and implementation of environmentally sustainable practices can be fostered (Redvers et al. 2022).

Policy and accountability

Information interventions, whilst valuable, often fall short in driving behavioural change when compared with incentivization strategies (Bergquist et al. 2023; Mitev et al. 2023). Policy changes that offer reward schemes and credits for households that demonstrate environmental stewardship may be more effective methods in inducing climate action than increasing awareness. The implementation of mandatory sustainability requirements and planetary impact assessments for new industries and businesses prior to their establishment should also be a priority. This involves quantifying and accounting for planetary health costs in economic evaluations. Greater accountability strategies will be needed in concordance with these changes to ensure compliance amongst individuals, organizations, and governments. Efforts must also be intensified to counter the spread of misleading reports and statistics that detract from the objectives of planetary health, highlighting the importance of accurate information dissemination in environmental conservation (Lewandowsky 2021).

Research and education

More investment in cross-disciplinary research will help to investigate the knowledge gaps that currently exist within planetary health, such as the disproportionate health effects on developing nations. Incorporating planetary health into university curricula will help to educate future leaders on the inextricable relationship between human and environmental health. From my experience as a medical student, the first time I encountered the concept of planetary health was in preparation for this essay. Whilst my undergraduate studies have involved teaching on sustainability, planetary health has yet to be introduced.

Personally, I view the concept of planetary health as an abrupt wake up call for humanity. A humbling moment in human history where for the first time, adopting a lifestyle of moderation, consideration and responsibility is no longer a choice, but a societal necessity. I think it prompts reflection – Do we revisit and uphold forgotten virtues, or continue towards a path marked by self-destruction? At this critical juncture, I believe that we must all embrace intellectual humility and acknowledge the flaws in our current practices as a prerequisite to finding long-term solutions to the challenges ahead. The mere ability to act does not justify all actions; it’s a reminder of the importance of thoughtful stewardship and the ethical considerations that should guide our interaction with the Earth.

Conclusion

The planetary health movement calls for a profound re-evaluation of humanity’s relationship with the Earth, advocating for a transition towards lifestyles and practices that prioritize sustainability and respect for our planet, for the sake of our own health and wellbeing. By exposing our dependence on the fragile integrity of natural systems, we can begin to address the fundamental causes of our environmental and health crises from a comprehensive perspective. Understanding the interconnectedness of our health with the health of our planet underscores the urgency of adopting an integrative, holistic approach that promotes individual and collective action towards wiser stewardship of the planet and a more equitable, sustainable, and healthier future for generations to come.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Sayed Adam Bukhari

Sayed Adam Bukhari is a medical student at King’s College London. His interests lie within planetary health research and education, specifically how such works can influence policy.