Addressing climate change to improve population health

The need to decarbonise healthcare is growing ever more urgent

Climate change is the greatest threat to population health in the 21st Century.

However, the delivery of modern healthcare comes with a very high environmental cost. Healthcare is a major emitter of greenhouse gases and carries a carbon burden of 4 to 8 per cent.

The top three healthcare emitters – the United States, China, and the European Union – comprise more than half of the global footprint of healthcare delivery. NHS data from 2019 identified that 62 per cent of healthcare emissions were derived from the healthcare supply chain, 24 per cent from delivery of care, and 10 per cent from healthcare-related travel (Figure 1(a) and (b)).

Figure 1(a): 2019 Contributions of different sectors to the greenhouse gas emissions of the NHS in England

Understanding the symbiotic nature of planetary and population health and taking steps to decarbonise the delivery of healthcare is an essential competency for all clinicians now and into the future.

The global policy framework to achieve net-zero emissions by 2050 aimed at curtailing climate change acceleration will also result in significant population health benefits.

This ‘co-benefit’ of climate action underscores the rationale for integrating environmental sustainability into population health strategies (Figure 2).

This opinion piece offers an overview of the current challenges, the global policy framework driving net-zero emissions by 2050, and the critical actions that can be taken at the local level to foster sustainable healthcare.

Climate change as a multi-faceted health challenge

Humanity has become a planetary force of change due to the rapid and widespread increase in human activity, which began in the mid-20th Century. This human activity, termed the ‘great acceleration’, has had a profound and deleterious impact on our planet’s health. It has led to rising global temperatures, the depletion of earth’s finite resources, and the loss of biodiversity. A significant and alarming milestone occurred in 2024, when global temperatures increased more than 1.5 °C above pre-industrial levels for the first time.

Without immediate and drastic intervention, in the next few decades, mankind will face severe consequences, such as declining health, climate devastation, millions of environmental migrants, and more pandemics. Modelling suggests that one person will die prematurely for every 1-4 kt CO² emitted, due to the diverse health effects of climate change.

Prof Cory Bradshaw (PhD), Professor of Global Ecology, Flinders University, Adelaide, Australia, reviewed over 150 conservation studies in 2021 and concluded that a “sixth major extinction” is already underway.

The World Health Organisation (WHO) has long highlighted the impact that climate change, air pollution, and biodiversity loss – ‘the triple planetary crisis’ – have on human health.

Air pollution is the leading cause of premature death worldwide. Over seven million people die each year because of the air they breathe. There is no safe level of long-term exposure to poor air quality and particulate matter. Worldwide, nine out of every 10 people breathe air that contains levels of pollutants that exceed WHO guidelines. In industrialised countries, air pollution is mainly caused by the use of non-renewable energy sources in factories and the burning of fossil fuels to drive transport. The Environmental Protection Agency in Ireland estimates that approximately 1,300 people die prematurely each year as a result of air pollution (Figure 3). The dramatic rise in car ownership over the past 50 years is the main contributor to poor air quality in Ireland, with almost 2.5 million cars on Irish roads burning fossil fuels.

In low-to-middle-income countries, an estimated 3.2 million people die every year due to indoor household air pollution from the burning of fossil fuels. Traditional cooking methods, such as using charcoal fires in poorly ventilated homes, are a significant source of toxic particulate matter causing air pollution. Rising global temperatures causing unprecedented widespread and prolonged wildfires are also contributing to a rise in air pollution.

Action on air quality can be improved by changing our behaviour, individually and collectively, so that we burn fewer fossil fuels to heat our homes and businesses and make the move to electric vehicular transport.

Increasingly, healthcare is on the frontlines in dealing with the impact of climate change, especially in the emergency and primary care settings. Prolonged unseasonal rises in temperatures result in surges of heat-related illnesses, vector-borne diseases, and mental health disorders. This places significant strain on healthcare systems.

Safe climate-resilient and environmentally sustainable healthcare facilities play a vital role in healthcare decarbonisation by ensuring that health systems can withstand and adapt to the impacts of climate change. A zero-emissions healthcare agenda must evolve alongside efforts to establish infrastructure, systems, and community resilience. This involves creating robust healthcare facilities and operations that can continue to function effectively during climate-related disasters and emergencies.  By integrating resilience with decarbonisation efforts, healthcare systems can better protect population health, reduce vulnerabilities, and maintain high-quality care in the face of climate challenges. The WHO has issued guidelines with this in mind to ensure that healthcare facilities can continue to function without disruption in an environmentally sustainable way despite the potential impacts of climate change. 

Healthcare’s carbon footprint: A call for decarbonisation

Decarbonising healthcare delivery is a key EU priority to achieve net-zero emissions by 2050 and help mitigate climate change. The main source of healthcare’s climate emissions is the burning of fossil fuels such as coal, oil, and gas. This accounts for 84 per cent of emissions from powering hospitals, healthcare travel, and the production and transport of healthcare products. To decarbonise, healthcare must switch entirely to clean, renewable energy across all aspects of its operations, including facilities, transport, supply chain, water and waste management, and models of healthcare. The HSE Climate Action Strategy is committed to achieving net-zero emissions by 2050, through the delivery of environmentally sustainable healthcare. Climate-smart solutions can also save money for healthcare systems and reduce the financial burden associated with the delivery of healthcare by lowering disease rates caused by pollution. Ms Kathy Gerwig is an international expert on healthcare decarbonisation. In her book Greening Health Care: How Hospitals Can Heal the Planet, she states that if “the healthcare industry conserved energy, reduced waste, and more efficiently purchased operating supplies, it could save more than $15 billion over 10 years”.

To achieve zero-emissions in healthcare, seven high-impact actions need to be implemented.

1. Switching to renewable sources of energy by using 100 per cent clean, renewable electricity.

2. Build and maintain zero-emissions energy-efficient healthcare buildings and infrastructure.

3. Transition to zero-emissions vehicles and promote sustainable travel options.

4. The provision of healthy, sustainably grown food and reduce food waste.

5. The production and use of low-carbon pharmaceuticals.

6. The implementation of sustainable waste management and circular economy principles.

7. Improve health system effectiveness by eliminating inefficiencies and enhancing resilience.

Changing clinical practices by introducing policies reflecting ‘green models of healthcare’ is crucial for decarbonising health systems, as it directly impacts the carbon footprint of healthcare delivery. By adopting sustainable practices, healthcare providers can reduce unnecessary and low-value care, which not only minimises waste, but also decreases emissions associated with medical procedures and treatments. This approach to delivering patient-centred care ensures that care provided is both effective and environmentally responsible, contributing to the overall goal of reducing the healthcare sector’s carbon burden. Additionally, promoting sustainable practices on the frontlines of care can lead to significant improvements in resource utilisation and energy efficiency, further aiding in the reduction of greenhouse gas emissions.

The Irish and UK surgical policy document, the Intercollegiate Green Theatre Checklist, is an example of such a model.  The document is a compendium of evidence with guidelines aimed at reducing the environmental impact of the delivery of surgical care. The carbon footprint of a typical surgical operation is estimated to generate between 150-170kg CO²e, which is equivalent to driving 450 miles in an average petrol car.

The main sources of carbon emissions in surgery include:

1. Anaesthetic gases: Anaesthetic gases contribute an estimated 2 per cent of the NHS’s total carbon emissions. Volatile anaesthetic agents, such as desflurane and nitrous oxide, have high global warming potential.

2. Single-use equipment: Consumables typically contribute 32 per cent of carbon emissions in surgical operations. Single-use components, especially in minimally invasive and robotic surgeries, significantly increase the carbon footprint.

3. Energy consumption: Heating, ventilation, and air conditioning systems contribute to more than 90 per cent of surgical theatres’ energy usage.  Anaesthetic gas scavenging systems and overhead radiant heaters also account for a significant portion of electrical energy used.

4. Waste management: Waste disposal, although accounting for less than 0.1 per cent of a typical operation’s carbon footprint, still contributes to the overall emissions.  The choice of waste stream can have a significant impact on the carbon footprint.

These sources collectively contribute to the high carbon footprint associated with surgical procedures. The checklist empowers the whole surgical team to take safe and effective steps along the patient’s surgical journey to deliver environmentally sustainable care.

Clinical leadership and advocacy

Clinicians play a crucial role in delivering the healthcare decarbonisation agenda. 

Without immediate and sustained intervention, emissions from healthcare systems could triple by 2050, undermining both climate and population health objectives.

Clinicians serve as advocates for environmental sustainability by influencing institutional policies, integrating climate-conscious practices into healthcare delivery, and supporting sector-wide initiatives to achieve net-zero emissions.

Clinicians are well positioned to drive interdisciplinary research collaboration towards the development of innovative, climate-resilient healthcare models. By aligning sustainability efforts with high-quality patient-centred care, they contribute to the evolution of a more effective and environmentally responsible health system. Clinicians as climate activists can fulfil both their ethical and professional obligation to protect population health and planetary health.

“Climate change is intrinsically linked to public health, food and water security, migration, peace, and security. It is a moral issue. It is an issue of social justice, human rights and fundamental ethics. We have a profound responsibility to the fragile web of life on this Earth, and to this generation and those that will follow.”

Former United Nations Secretary-General Mr Ban Ki-moon

Authors: Prof Camilla Carroll, Consultant Otorhinolaryngology Head and Neck Surgeon, Royal Victoria Eye and Ear Hospital, Dublin; and Mr Muhammad Umair, Consultant Colorectal Surgeon, Midland Regional Hospital, Tullamore, Co Offaly