Intended for healthcare professionals


Remembering the mission on healthcare’s path to decarbonisation

BMJ 2021; 375 doi: (Published 19 November 2021) Cite this as: BMJ 2021;375:n2847

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  1. Renee N Salas, physician researcher1
  1. 1Department of Emergency Medicine, Harvard Medical School, Boston, MA, USA
  2. Twitter: @ReneeNSalas_MD


Clinicians are driven by a common mission: to optimally improve health, prevent harm, and advance equity. This means we cannot be satisfied with just a 5% reduction in the haemoglobin A1c for diabetics or blood pressure for those with hypertension. These small reductions only serve as an intermediate step on a path to fully treating the condition in the patient in front of us.

This same mission must be applied to the climate crisis, a health emergency that is inequitably jeopardizing the health of people around the globe. Only a swift reduction in global greenhouse gas (GHG) emissions to net zero, primarily carbon dioxide, will fully treat this condition. This includes the intermediate step of decarbonising the healthcare sector, which currently represents nearly 5% of global emissions and upwards of 8.5% of domestic emissions in the United States.12 Improving health and advancing equity can serve as a guide for not only the necessity and motivation driving healthcare decarbonisation, but also ensuring it urgently catalyses global economy-wide decarbonisation.

Healthcare decarbonisation is a prescription for improved health and equity

The burning of fossil fuels drives both climate change and air pollution, which directly and indirectly harm health across every organ system—disproportionately impacting the vulnerable—and disrupting the delivery of healthcare.3 Meanwhile, the healthcare sector produces more GHGs, creating a vicious cycle that must be broken.

The harms to our patients are occurring here and now, ranging from the clinically insignificant, like a transient cough from poor air quality, to significant morbidity and mortality. Secondary diagnoses are often conditions that make it harder for us to prevent or manage a patient’s primary ailment. Thus, climate change and air pollution are critical secondary diagnoses that frequently go unrecognised.4

Yet, once these diagnoses are made, our common mission of improving health and equity mandates that we use treatments outside of our usual toolbox, which includes healthcare decarbonisation. The burning of fossil fuels is like an outdated medical treatment. In the past, it was all we had, but now there are healthier and safer options, like solar and wind energy. We just need the collective will to rapidly proceed with an equitable energy transition, and the healthcare sector must lead by example because our mission demands it.

Healthcare decarbonisation can catalyse global economy-wide decarbonisation

The theory of change model operationalises the concept of mission-driven change.5 By identifying the ultimate end goal, one can then determine what the ideal intermediate steps are along the way to achieve it. This ensures that each intermediary step within the sphere of influence is developed and measured to optimise its impact on the end goal—never losing sight of the ultimate mission.

The end goal for climate change is a reduction of half of the globe’s GHG emissions by 2030 and reaching net zero by 2050—and leaving fossil fuels in the ground. Just like managing hypertension, our goal is 100% reduction and not just a 5% reduction within the healthcare sector.

Applying the theory of change model, healthcare decarbonisation becomes a crucial intermediate step on the path to this goal of global decarbonisation.6 With this view, it can be optimally developed and measured to serve as a catalyst that accelerates wider action to the breadth and speed required to forestall the worst impacts of climate change. The first domino to fall. Healthcare makes up 10% of the global gross domestic product and can use its economic influence to push vital levers of action, such as those within the electricity sector and supply chain system.7 Once the dominos start to fall, nothing can stop the chain reaction.

And the dominos must start falling soon. The latest report from the Intergovernmental Panel on Climate Change says we are on a path to potentially reach a global average temperature that is 1.5°C above the pre-industrial average within the next two decades.8 A recent study also revealed that nearly 90% of the world’s coal must remain unextracted to have even a 50% chance of limiting warming to 1.5°C by 2050, and approximately 60% of oil and fossil methane gas must be left in the ground.9 Even achieving these goals leaves us with odds equivalent to a coin toss. Increasing our chances with more ambitious effort is essential because every fraction of warming translates to worse health and more health system disruption.

The healthcare sector is bonded together in our common mission, which is our strength, and it demands that the catalysing power of healthcare decarbonisation be optimally harnessed. We cannot be satisfied until climate change is fully treated.


  • Renee N. Salas is affiliated faculty and previous Burke Fellow at the Harvard Global Health Institute, a Yerby Fellow at the Center for Climate, Health, and the Global Environment at the Harvard T.H. Chan School of Public Health, and an emergency medicine physician at Massachusetts General Hospital and Harvard Medical School.

  • Competing interests: none declared

  • Provenance and peer review: commissioned, not peer reviewed


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