IN A 2011 EDITORIAL IN THE BRITISH Medical Journal (BMJ), Fiona Godlee, editor-in-chief, wrote that “the greatest risk to human health is neither communicable nor noncommunicable disease — it is climate change”.

Writing this took courage: at that time, only 10 years ago, it felt risky to persuade busy doctors to worry about climate change. But things have changed: human and planetary health are now central to the global climate agenda. In the run-up to COP26, the BMJ and more than 200 other health journals published a joint editorial calling for emergency action to limit global temperature increases, restore biodiversity, and protect health. The medical establishment was slow in realising this.

Scientists and a growing number of activists have argued since the 1960s that burning fossil fuels produces greenhouse gases that change the climate. Those changes affect all life and harm our health and health systems.

This article explores the relationship between modern health systems and climate change, and the implications of that relationship.

Climate change affects our health

There are primary, secondary, and tertiary health risks from climate change:

• Primary risks are direct results of extreme weather events: heat waves, floods, droughts, hurricanes and cyclones.

• Secondary risks come from changes in natural and biological systems including water flows and disease vectors like mosquitos, ticks and bats, and food production.

• Tertiary risks are more indirect. They include mental health impacts, social insecurity, population displacement, conflicts, and war over dwindling resources.

A flooded market centre in Kisumu, Kenya. Primary health risks are direct results of extreme weather events: heat waves, floods, droughts, hurricanes and cyclones.

These risks are most felt in the low-and middle-income countries (LMICs) least prepared to cope with them. Sub- Saharan Africa is one of the regions least responsible for climate change. Yet it is the most vulnerable region on the planet. The most vulnerable people are children and women, the poor, the unemployed, those living in crowded homes in peri-urban slums, and those in rural areas. And those are the people who have the least access to good health services.

Health systems contribute to climate change

“The medical establishment has become a major threat to health.” – Ivan Illich, 1974

If climate change is a major threat to health, it is ironic that modern health care is also a threat to the climate. It produces almost 5% of global greenhouse gas (GHG) emissions. If the world’s health systems were a country, it would be the fifth-largest climate polluter on the planet. Instead of promoting and protecting our health, our health systems are actually undermining it.

The Sustainable Development Unit of the National Health Service (NHS) in England is a leading institution on health system emissions. It has been tracking and reporting on NHS emissions since 2008.

Most NHS emissions come from supply chains – the production, transport, and eventual disposal of goods and services, including medicines, food and agricultural products, medical instruments, and hospital equipment. About a quarter comes from the transport of goods, and travel by staff, patients, and visitors.

In 1990 the NHS emitted 33.8 million tons of CO2 equivalent (MtCO2e) per year. By 2000 it had fallen to 27.5 MtCO2e, mainly due to phasing out chlorofluorocarbon propellants in inhalers, reducing reliance on coal and oil for on-site heating, and reductions in supply chain emissions from pharmaceuticals, chemicals, and gases.

Hospital admissions resulted in greater GHG emissions than outpatient visits. This implies that eliminating unnecessary hospital admissions and reducing the need for admissions would mitigate health system emissions.

Other key steps would include shifting admissions from central to district- and community-based settings and reducing unnecessary medical and surgical interventions through the use of relevant peer-reviewed evidence.

But mitigating health GHG emissions through optimal use of resources in the delivery of clinical care, though essential, is not enough to ensure sustainable health care.

We must rediscover old ways and find new ones to understand, imagine, and think about health, about being healthy, and about health care.

Comprehensive Primary Health Care essential

We must revitalise the global project to achieve Health for All through Primary Health Care (PHC), as set out in the spirit of the 1978 Declaration of Alma-Ata.

The most vulnerable people are children and women, the poor, the unemployed, those living in crowded homes in peri-urban slums, and those in rural areas. Those are the people who have the least access to good health services.

PHC is a profoundly political rather than a technical project. It regards health as a fundamental human right and addresses not only universal access to health care but also the structural determinants of health – the goods, services, and environmental conditions that are essential for good health. PHC challenges power blocs with material vested interests in technical approaches to health and health care and – as is becoming clearer – technical approaches to addressing climate change through the “net zero” idea.

We must revitalise Comprehensive Primary Health Care (CPHC). Quality CPHC sees equity as fundamental and includes health promotion, disease prevention, low-impact curative care, and rehabilitation. Activities occur predominantly at lower-level facilities (health centres and clinics) and at the community and household level. Quality health care should be freely and universally accessible within the community and close to home.

CPHC will mitigate the burden of ill health, reduce the transport needs of the health system, cut the need for hospital admissions and their waste, and thus eliminate a large proportion of health system GHG emissions.

Well trained and equipped community health workers (CHWs) with decent working conditions, remuneration and support systems are essential for such systems. They should provide much of the care in the household. CHWs recruited from local communities can facilitate meaningful community participation in matters concerning health – a fundamental requirement of CPHC.

But making health systems greener will not fully address the complex health challenges associated with the global ecological crisis. Underneath lie deep structural inequalities – of income and wealth, of vulnerability to risk, of gender and race, and of political power. For economic and political reasons, large sections of the world’s people lack access to the social determinants of health.

Improving equity in access to the SDH needs collaborative intersectoral action by state sectors, including those responsible for education, agriculture, the environment, transport, safety and security, and so on. Addressing the SDH is therefore beyond the scope of the health sector alone.

Adaptation: some thoughts

Climate change will continue to degrade the natural world on which we all depend for our health. The Covid-19 pandemic is far from over, and new pandemics will follow. Extreme weather, heatwaves, droughts, hunger, insecurity, conflict and societal breakdown are already compelling people who have the ability and the means however meagre, to migrate for their survival, or simply out of desperation. What will they encounter on the way? Who will they meet? Will they find asylum? Will they survive?

Involuntary migration whether due to extreme weather, human rights violations, persecution or conflict – and these often flow together – adds to already stretched services and infrastructure, including education and health systems. New conflicts for available resources emerge, with waves of intolerance, xenophobia, racism, and interpersonal violence. We can see this unfolding in many parts of the world already, including in the Global North. But the major impacts are on vulnerable people in the Global South, especially children, women, and the disabled. And these are the people with the tiniest, most marginal, footprints on mother earth.

History shows that we can’t rely on governments or the market to respond adequately to the challenge. It is incomprehensible but true: enormously powerful vested interests continue to drive this destruction of the future. The global ecological crisis will continue while capitalism dominates.

In its elaboration of Primary Health Care, the Declaration of Alma- Ata emphasised a transformative, developmental approach to health. It supported the call from the Non-aligned Movement for a just New International Economic Order (NIEO) to allow “developing” countries to achieve the economic equivalent of their newly- acquired political independence.

This vision of a NIEO threatened the prevailing status quo, which was biased in favour of industrialised countries. As expected, it didn’t go down well in the corridors of power, particularly in the UK and the USA, where the foundations of neoliberalism were being laid. The result was that, instead of a more just global economic system, the NIEO that came to prominence in the 1980s was based on endless growth through extractive capitalism.

Today we are dealing with the devastating impact on society and the ecosystem. How should we respond to a world that is changing so quickly and with such momentum? Clearly, our health systems must decarbonise, adapt themselves to deal with the inevitable changes in disease patterns that emerge. Furthermore, they must transform themselves to be able to revitalise PHC in its radical, transformative interpretation.

And all of us must reimagine what “development” means and develop an alternative to the endless growth model. We have no option but to continue the struggle for a better world. To do so, we must keep our humanity, our love and respect for others and the planet consciously alive.

Louis Reynolds is a retired associate professor of paediatrics and a longstanding activist in the People’s Health Movement. This article is written in his personal capacity.