There Are No Healthy Humans on an Unhealthy Planet
I was running through Forest Park on a morning I still think about.
No headphones. Just the sound of wind moving through the trees, a creek somewhere below the trail, birds doing their thing. My two boys were three and one at the time. And out of nowhere, a thought arrived that I didn’t ask for and couldn’t shake: that they might never get to hear this. If we let climate change go unchecked. If we just don’t do enough.
I remember thinking: I’m just an Emergency Room doctor. What can I do about this?
That question sent me down a path I haven’t stopped walking. And what I found surprised me.
Why This Belongs in Medicine
Climate change is real, it is driven by human activity, and it is already making people sick. That is not a political statement. It is a medical one.
A 2020 paper by Sorenson and colleagues was the one that crystallised it for me. It outlines in detail the range of pathologies directly exacerbated by a warming planet and argues that the emergency physician’s role is one of advocacy and action. When I read it, my trail-run question started to have an answer.
Here is the clinical picture, condensed:
• Air pollution — the most significant environmental cause of disease and premature death on Earth. In 2015, pollution-related diseases caused an estimated 9 million premature deaths, representing 16% of all deaths worldwide. Three times more than AIDS, tuberculosis, and malaria combined. The main driver is fossil fuel combustion. And the equity dimension is stark: burning fossil fuels in high and middle-income countries generates 85% of airborne particulate pollution in low-income countries. We export the pollution; they absorb the consequences.
• Heatwaves — following a 2011 heatwave in Sydney, all-cause ED visits rose by 2%, ambulance calls by 14%, and mortality by 13%. In France in 2003, an unprecedented heatwave caused 14,800 excess deaths. Projections suggest a 1.6% increase in all-cause mortality and a 25% increase in heat-related mortality by century’s end, with disproportionate effects on those under 18 and over 65.
• Wildfire smoke — PM2.5 exposure from wildfires drives measurable increases in asthma exacerbations, COPD presentations, and ischemic heart disease. The effects on ED presentations can persist for up to three days after the inciting event.
• Infectious disease — as human settlements expand into previously wild areas, the conditions for zoonotic disease breakthrough grow. SARS-CoV-2 was not an anomaly. It was a preview.
• Natural disasters — in 2017, Hurricane Harvey flooding reduced hospital capacity by approximately 40%, with beds lost to water damage, staff unable to reach facilities, and patient transfers halted.
And across all of the above, the communities absorbing the highest burden are the same ones already marginalised by income, race, age, and geography. Climate change is a health equity issue. It arrives in our ED every shift.
The Uncomfortable Truth About Healthcare Itself
The US healthcare sector is responsible for approximately 8.5% of national greenhouse gas emissions. If it were a country, it would rank in the top 15 global emitters. About three-quarters of those emissions originate from the supply chain — procurement decisions, device manufacturing, pharmaceutical production.
We are part of the problem. Which means we have standing — and responsibility — to be part of the solution.
When residency programs at Oregon Health and Science University shifted to virtual interviews during COVID-19, our analysis estimated median savings of 0.47 metric tons of CO₂ and $490 per applicant per cycle — the carbon equivalent of approximately 22 mature trees sequestering carbon for a year. Austin–Travis County EMS transitioned to hybrid and biodiesel ambulances, saving 14.2 metric tons of CO₂ annually while cutting fuel costs.
Change is possible. It just requires people inside the system to decide to act.
The Educate, Mitigate, Advocate Framework
Here is the practical framework I use when I think about what physicians and healthcare workers can actually do. Three verbs. Scalable to where you are.
Educate
The ED visit is often the only healthcare touchpoint some patients have in a year. That 30-second conversation at the bedside matters. When you discharge a patient after a smoke-related asthma exacerbation, pull up AirNow.gov together and show them how to read the air quality index for their neighbourhood. When you see an elderly patient during a heat wave, review which of their medications increase heat risk, and tell them where their nearest cooling centre is. Document it in the chart the same way you would tobacco counselling. Normalise it.
For those in graduate medical education: our scoping review of GME climate curricula found only 17 published accounts of climate-related topics across all US GME programs. Seventeen. Emergency Medicine had the most — and it still wasn’t enough. A single slide embedded in an existing lecture is a starting point. Climatehealthed.org has ready-made, evidence-based decks. Start there.
Mitigate
Select one sustainability goal per year and build a quality improvement cycle around it. Track CO₂ equivalents alongside your usual QI metrics. Frame it in the language administrators understand: resilience, risk reduction, cost savings. A renewable energy source that keeps the hospital running during grid failures in a disaster event is not an environmental luxury — it is patient safety infrastructure.
Advocate
When contracts come up for renewal, ask vendors for Environmental Product Declarations or Scope 1–3 emissions data. Make sustainability a bid criterion. Run tabletop drills with climate-specific scenarios — wildfire smoke, flooding, extreme heat. Mentor your trainees. One resident-led QI project on heat protocols or waste stream analysis can seed a departmental movement. Seeing faculty care about this topic gives trainees permission to engage.
The Diet Piece
Deforestation is driven largely by land cleared for animal agriculture. So when we talk about reducing red meat consumption, we are having a climate conversation and a health conversation at the same time.
The EAT-Lancet Commission demonstrated that universal adoption of a plant-rich diet with severe limitation of red meat consumption could prevent approximately 11 million premature deaths per year through 2050.
In practice: when a patient presents with chest pain and we discuss diet, I ask what they know about the link between red meat and heart disease. Then I also tell them what it costs the planet to produce that beef — and what happens when you swap it for beans, lentils, or tofu. One conversation. Two wins.
How Should This Modify Your Practice?
• If you are a healthcare professional: Pick one thing from the Educate, Mitigate, Advocate framework and commit to it this month. Document one climate health conversation. Launch one QI cycle. Bring one data point to your next faculty meeting.
• If you are a member of the general public: Bookmark AirNow.gov. On high-pollution or high-heat days, modify outdoor activity if you have lung or heart disease. Look at your diet — even one or two plant-forward meals per week is a meaningful start.
• Everyone: Use your voice. At the ballot box, in community meetings, in conversations with your GP. Physicians rank among the most trusted messengers in public discourse on health. So do you.
The time to act was in the 1980s. We didn’t act fast enough. But we are not out of options. The evidence on what happens when communities and healthcare systems commit to action is genuinely hopeful. We just have to be brave enough to start.
There are no healthy humans on an unhealthy planet.
Fewer bad days. More good decades.
Extend Yourself
This episode of Overheard in the Emergency Room goes deeper — including a full clinical breakdown of climate-related disease categories, the Educate-Mitigate-Advocate framework in detail, mythbusting on electric vehicles and regenerative beef, and a practical three-step action plan for this month.
You can listen on Spotify, watch on YouTube, and find the full episode notes and references at drcois.com.
Dr Cois
Emergency Physician. Creator of Overheard in the Emergency Room. Founder of DrCois.com — evidence-based medicine for everyday people. Fewer bad days. More good decades.
References
1. Sorensen C, Murray V, Lemery J, Balbus J. Climate change and women’s health: Impacts and policy directions. PLOS Med. 2018;15(7):e1002603. doi:10.1371/journal.pmed.1002603
2. Cois A, et al. [Resident’s Perspective on climate change and emergency medicine — Author’s own publication; full citation to be confirmed against published version]
3. Neumann JE, Anenberg SC, Weinberger KR, et al. Estimates of present and future asthma emergency department visits associated with exposure to oak, birch, and grass pollen in the United States. GeoHealth. 2019;3(1):11-27.
4. Johnston FH, Hanigan IC, Henderson SB, Morgan GG. Evaluation of interventions to reduce air pollution from biomass smoke on mortality in Launceston, Australia. Bull World Health Organ. 2013;91(3):219-224.
5. Kenney CM, Bhatt DL, Bhavnani SP, et al. Impact of Hurricane Harvey on regional cardiovascular emergency care. Am Heart J. 2021;234:79-88.
6. Eckelman MJ, Sherman J. Environmental impacts of the U.S. health care system and effects on public health. PLoS ONE. 2016;11(6):e0157014. doi:10.1371/journal.pone.0157014
7. Domingo A, Singer J, Cois A, et al. Carbon footprint and cost of virtual residency interviews. [Full citation to be confirmed against published version]
8. Giudice EL, Rublee CS. Climate change, air quality, and emergency medicine. Ann Emerg Med. 2023. [Full citation to be confirmed]
9. Cois A, et al. Climate change in US graduate medical education: A scoping review. [Full citation to be confirmed against published version]
10. Willett W, Rockström J, Loken B, et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet. 2019;393(10170):447-492.
11. International Council on Clean Transportation. Lifecycle emissions from electric vehicles. ICCT White Paper. 2021. [Full citation to be confirmed]
