Intended for healthcare professionals


An unequivocal call to climate action for the health sector

BMJ 2022; 376 doi: (Published 18 March 2022) Cite this as: BMJ 2022;376:o680
  1. Naomi Beyeler, managing director1,
  2. Renee N Salas, physician researcher2
  1. 1University of California Center for Climate, Health and Equity, San Francisco, CA, USA
  2. 2Harvard Global Health Institute, Cambridge, MA, USA
  1. Correspondence to: R N Salas rnsalas{at}

Latest UN IPCC report must not be ignored

The word unequivocal is rare in medicine and stands out in the latest report of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC), which states that “the human toll of climate change is unequivocal and growing.”1 The report issues three clear warnings and a call to action for everyone in the health sector.

Accelerating harms

First, the health harms associated with climate change are worse, and happening sooner, than expected.1 Since the IPCC’s last report on impacts and adaptation eight years ago, the climate crisis has accelerated, as has our understanding of the health implications.12 Evidence indicates that some health harms not anticipated until later this century are already being felt. Half of the world’s population live in places vulnerable to climate change, and millions face food and water shortages and major disruptions to their lives and livelihoods.1 This contributes to migration, displacement, and conflict—all with cascading effects on health.

The latest report found evidence for a broad range of health consequences, including increases in heat related deaths, infectious diseases, and malnutrition.1 Most notably, the report identified the devastating effect of climate change on mental health and wellbeing, especially among young people. At 1.1°C above pre-industrial levels, climate change already affects every aspect of our health13 and undermines efforts towards universal health coverage.4

Second, we are rapidly approaching critical risk thresholds.15 The IPCC evaluated multiple climate threats with health implications, from the loss of ecological systems to extreme weather events. In each area of concern, human harm is now expected to occur at lower global average temperatures than previously reported. Moreover, adaptation becomes impossible above a certain level.1 Accelerating warming is projected to surpass important risk thresholds for multiple health outcomes, including heat related deaths.

Third, the report expanded previous warnings about maladaptation to climate change.1Maladaptations are responses that worsen health, amplify vulnerability, deepen inequity, and limit the possibilities for transformational solutions. Air conditioning, as a health adaptation, is energy intensive, contributes to air pollution, and can be unaffordable and inaccessible to vulnerable populations.67 Low income and socially marginalised communities might also have limited access to interventions such as cooling centres and urban green spaces, leading to a greater risk of heat exposure and further widening of inequity.

Effective action

In the face of these warnings, the IPCC offers hope: the health community can take effective action today to dramatically reduce—and in some cases prevent—the worst health outcomes. We must build strong, climate resilient health systems. Expanding access to universal health coverage is fundamental for adapting to climate change, and health systems must increase capacity to cope with rising rates of poor mental health. Early warning systems for heat events, increased emergency response capacity, surveillance of climate sensitive disease, vector control programmes, and water and nutrition interventions are other critical adaptations that should be expanded.18 These efforts must serve the needs of those hit hardest by climate change, including low income countries and communities, migrants, displaced populations, Indigenous people, women, children, older people, and other marginalised groups.19

The report emphasises, however, that adaptation alone is not enough. Limiting global warming to 1.5°C above pre-industrial temperatures through a rapid transition away from fossil fuels is the best path to avoid the most catastrophic threats to human health.10 Affordable options for clean energy and transportation (such as walking and cycling), urban green spaces, healthy buildings, and sustainable food systems are beneficial for both human and planetary health.11 Importantly, these steps would also reduce air pollution from fossil fuels, which currently causes an estimated 8.7 million deaths each year worldwide.12

The move to a sustainable economy can start in the health sector, which contributes nearly 5% of global emissions.3 Decarbonisation of healthcare systems would catalyse action in other sectors, while also strengthening health system resilience.1314 The health response is not only about what we do, but how we do it. Efforts to tackle climate change, including adaptation must promote health and social equity. For wealthy countries, this includes scaling up financing to support the countries most affected by climate change.

The IPCC’s warning comes at a time of major social disruptions, including an ongoing pandemic and a devastating war in Ukraine. Health professionals and the communities we serve are facing tremendous stress, but we must not turn our attention away from the climate emergency.

All health professionals have a responsibility to improve health through equitable adaptation and health system decarbonisation. But, perhaps most importantly, we must use the power of our expertise and moral voice to advocate for the transformational changes required to stop the burning of fossil fuels.

The IPCC’s diagnosis is clear: climate change is the leading threat to health and wellbeing globally, and our window to act is rapidly closing. The only appropriate response is immediate, unequivocal action.


  • Provenance and peer review: Commissioned; not externally peer reviewed.

  • Competing interests: We have read and understood BMJ policy on declaration of interests and do not have any conflicts of interest to declare.


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