Climate Change and Health Resource Center

Climate Change and Health Resource Center


Intergovernmental Panel on Climate Change. Sixth assessment report. Accessed Oct. 14, 2021.

Disclosures: Brown, Dacones, Damle, Dresser, Ebi, Eckelman, Freedman, Kuwahara Mark, Salas and Tummala report no relevant financial disclosures. Strak reports receiving support from the Health Effects Institute. Healio Primary Care could not confirm Lawrence and colleagues’ relevant financial disclosures at the time of publication.
October 29, 2021
11 min read

PCPs face mounting responsibility to address health effects of climate change


Intergovernmental Panel on Climate Change. Sixth assessment report. Accessed Oct. 14, 2021.

Disclosures: Brown, Dacones, Damle, Dresser, Ebi, Eckelman, Freedman, Kuwahara Mark, Salas and Tummala report no relevant financial disclosures. Strak reports receiving support from the Health Effects Institute. Healio Primary Care could not confirm Lawrence and colleagues’ relevant financial disclosures at the time of publication.
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Human influence has had an unequivocal impact on Earth’s climate, causing significant changes that threaten people’s security and physical and mental health, according to a landmark report from the Intergovernmental Panel on Climate Change.

The report stated that life-threatening climate extremes like heatwaves, tropical storms and droughts will become more common, and some changes on Earth’s climate are now irreversible.

Graphical depiction of data included in article.
Health care’s climate footprint. Accessed Oct. 14, 2021. 

“We are getting close to the point of no return,” Nitin Damle, MD, MS, MACP, past president of the ACP, told Healio Primary Care in reaction to the Intergovernmental Panel on Climate Change (IPCC) report.

Primary care physicians have a responsibility to educate patients about the health risks associated with climate change, he said.

Glimpse at current state of climate change

The IPCC estimates that emissions from greenhouse gases due to human activity have caused a global warming of about 1.1°C since 1850. Temperatures are expected to rise 1.5°C or more in the coming decades. A warming of 1.5°C will cause more heat waves, lengthier hot seasons and shorter cold seasons. At 2°C of warming, “heat extremes would more often reach critical tolerance thresholds for agriculture and health,” according to the IPCC. The authors of the report called the warning a “code red for humanity.”

Several media outlets have reported that extreme weather events predicted for future years have already begun. In 2021 alone, there were droughts, wildfires, record-breaking heat waves, rainfall and tropical storms.

Physical health effects

Climate change-fueled events and disasters have an excessive impact on populations, causing mass migrations and food insecurity. Rising temperatures and more frequent extreme heat events are associated with increased hospitalizations, lower safety and productivity among outdoor workers, limited outdoor exercise and exacerbated asthma, respiratory issues and airborne allergies, the IPCC report stated.

Other climate-sensitive health issues include wildfire smoke-associated particulate matter pollution, food-related leptospirosis and vector-borne diseases, Renee N. Salas, MD, MPH, MS, an attending physician in the department of emergency medicine at Massachusetts General Hospital and assistant professor at Harvard Medical School, and Kristie L. Ebi, PhD, MPH, a professor in the Center for Health and Global Environment at the University of Washington, reported in the Annals of Internal Medicine.

“Climate change is a health crisis, above all else, and the health community has an obligation to intervene,” Salas and Ebi wrote.

In regions impacted by wildfires, individuals have a 2% greater risk for cardiovascular, respiratory and all-cause mortality per 10 g/m3 of fire-related PM2·5, according to an editorial published in The Lancet Planetary Health. A recent study in The BMJ found that long-term exposure to outdoor air pollution was linked to mortality even at pollution levels below air quality standards in the U.S. and Europe. In light of emerging research on the health effects of climate change, WHO recently updated its air quality guidance to protect people from pollutants, which are a major cause of noncommunicable diseases like ischemic heart disease, stroke and cancer, in addition to respiratory diseases, WHO Director-General Tedros Adhanom Ghebreyesus, PhD, MSc, said during a press briefing.

Overall, the prevalence of physical health effects of climate change has been “accelerating,” Caleb Dresser, MD, MPH, instructor at Harvard Medical School and emergency physician at Beth Israel Deaconess Medical Center, told Healio Primary Care.

Caleb Dresser

“More abrupt events such as wildfires and floods have put an urgent spotlight on the impacts climate change is having on our well-being,” he said.

Mental health effects

Mental health conditions are also expected to become more frequent following severe weather, according to Emma Lawrence, DPhil, a mental health innovations fellow at the Institute of Global Health Innovation in the U.K., and colleagues. In a recent article, Lawrence and colleagues reported that a 1°C increase in temperature correlated with an approximate 1% increase in suicide. Based on this trend, the researchers estimated there could be 22,000 additional suicides in the U.S. and Mexico alone by 2050. They also noted that socioeconomic disruption such as poverty and migration due to climate change has been linked to depression, anxiety and PTSD.

“Climate change and mental health are two of the most significant and pressing challenges facing societies across the world. Yet, growing awareness of these global issues has not been met with sufficient action to mitigate their impacts,” Lawrence and colleagues wrote.

Lily Brown

Lily Brown, PhD, the director of the Center for the Treatment and Study of Anxiety at the University of Pennsylvania, conducted a study in 2016 to explore how exposure to natural disasters can impact mental health. She and her colleagues interviewed nearly 3,000 individuals before and after they experienced a major earthquake in Chile. They found that people who already had trauma exposure and PTSD prior to the natural disaster were much more likely to consider suicide.

“Those individuals essentially became sensitized to the impact of the disaster, meaning it impacted them to a greater extent in terms of their thoughts about suicide,” Brown told Healio Primary Care.

Individuals who survive a severe climate event may warrant a PTSD diagnosis, Brown said, while others might suffer from a generalized anxiety disorder.

In the event of a migration, the mental health consequences “can affect people’s ability to integrate into a new community,” Dresser said. This could prevent them from reestablishing “effective health care,” he added.

Marginalized populations disproportionately affected

Damle said that physicians in primary care practices, EDs and urgent care centers in the U.S. will see an increasing number of patients with conditions related to climate change. Certain populations are more vulnerable to these health effects. 

Neelu Tummala

“Outdoor workers are especially susceptible to the health impacts of heat extremes as they work outdoors for extended periods of time. Until recently, there was no national standard in place to protect the health of these workers, but the Biden administration recently announced plans to draft guidelines to protect outdoor workers,” Neelu Tummala, MD, a physician in the otolaryngology department at George Washington University’s Medical Faculty Associates, told Healio Primary Care. “Low-income communities are also at increased risk as they are less likely to have adaptation strategies in their homes, including access to shade, air conditioning and sufficient water to adapt to these heat extremes.”

Darcy Freedman

Heat stress also disproportionately impacts Black and Brown communities “due to racialized patterns in who has access to parks with pools or tree-lined neighborhoods,” according to Darcy Freedman, PhD, MPH, the Mary Ann Swetland Professor at Case Western Reserve University School of Medicine. A study in Earth’s Future showed that among 1,056 U.S. counties, 71% had significant racial urban heat disparities. This finding persisted after adjustments for income.

Climate change is an issue of health equity and “one of our most significant health threats,” according to Rita K. Kuwahara, MD, MIH, a primary care internal medicine physician and health policy fellow at Georgetown University and Healio Primary Care Peer Perspective Board member.

“A person’s zip code already correlates with life expectancy in the U.S., driven largely by historic segregation and racism. Communities most impacted by the ill effects of climate change are often communities of color and located in regions where individuals have historically experienced worse health outcomes,” she said.

Beth Mark

Although climate change affects everyone, Beth Mark, MD, MES, a psychiatrist at the University of Pennsylvania’s Counseling & Psychological Services, as well as a member of the Climate Psychiatry Alliance’s Steering Committee, said it is “essential to highlight that people with less types of privilege are more severely impacted, and people with more privilege can, at least for now, literally buy some time and a bit of distance from the most severe impacts.”

Assessments and universal screenings

As climate change becomes an increasingly present threat, Mark encouraged physicians to assess patients for climate-related distress.

“Once the physician signals that it’s not only OK to talk about [climate change] but that it’s important to maintain health, the patient is more likely to feel comfortable bringing up any climate-related concerns they may have,” Mark said. “I think that it’s important patients hear from their doctors that to be worried and upset about climate change is a normal reaction to a real threat.”

Brown hypothesized that the mental health effects of climate-related disasters could accumulate over time. PCPs can help address these accumulating mental health effects through universal screenings, she added.

Although PCPs are “exceptional” at assessing for depression, Brown said they often do not ask patients about exposure to trauma or PTSD.

“People have varying degrees of comfort with self-disclosing that they have been struggling with anxiety, depression or PTSD,” Brown said. “What I tend to recommend is to think about asking the same questions to everyone and not assuming that just because a mental health characteristic isn’t obvious to you and your evaluation with a patient, that doesn’t mean that it’s not a significant concern for that patient.”

Brown encouraged PCPs to consider including these assessments during routine examinations, as they are “very relevant” to climate change and “other stressors that the world is currently experiencing.”

Mark said that physicians have a duty to help patients protect themselves from the harmful effects of climate change. For example, physicians should advise patients who take medications that effect thermoregulation that due to rising temperatures, they need to pay extra attention to their surrounding temperatures both inside and outside and seek cooler environments when appropriate. Similarly, physicians should advise student athletes who present for a sports physical to keep track of the temperatures they are active in, seeking shade when possible (if outdoors) and keeping hydrated. Physicians should review the signs of heat illness with their patients and what their patients can do to minimize risk, Mark said.

“A lot of what primary care is about is doing a good job of keeping people healthy. I think part of the conversation, just as we talk about social determinants or social influencers of health, has to be about climate determinants or climate influencers of health, such as whether you live in a neighborhood that gets exceptionally hot during summertime heat waves,” Dresser said.

Community awareness and education

According to a 2020 U.S. Government Accountability Office report, “unclear federal leadership is the key challenge to climate migration as a resilience strategy.” Due to an absence in leadership, health care workers have a greater responsibility to educate patients about the threats associated with a warming climate.

“We need to spread the word as physicians to our patients about the health effects of climate change, if not in the exam room, then in a community setting,” Damle said. Physicians can give talks at community centers, town halls or schools about climate change and its effects as well as more sustainable and healthy behaviors such as a plant-based diet. Discussing this topic directly with patients can be challenging, however.

Nitin Damle

“Having conversations around climate change and its effects is difficult because exam rooms should be politically neutral places, where patients feel safe. They shouldn't feel like they have to defend their position,” Damle said. “However, if they bring it up and they want to know more, then certainly I think it’s an appropriate place to talk about it. If they don’t, then I think you can talk in broad, general terms such as heat waves and heat stroke or air pollution and asthma.”

Kuwahara recommended that PCPs engage in conversations with policymakers on the detrimental health effects of climate change “in order to truly effect change.” She added that, “while it is vital for us to hear from our patients how climate change negatively affects our patients’ health, it is not enough to just have these conversations with our patients.”

Instead, Kuwahara said that PCPs should advocate for patients and “regularly speak with elected officials to push for strong and sustainable solutions.”

Rita K. Kuwahara

“As physicians, we should collectively stand up and speak with our elected officials about the negative health effects of climate change that we are witnessing firsthand from our patients and share the stories our patients tell us regarding how their lives and health have been disrupted and worsened by climate change, in order to push the administration and Congress to prioritize and adopt policy changes that comprehensively address climate change, so that we may improve the health of communities throughout our nation,” Kuwahara said.

An unsustainable industry

Although PCPs hold a responsibility to educate and warn about the physical and mental effects related to climate change, the health care industry itself perpetuates climate-related illnesses. The industry is one of the most carbon-intensive service sectors in the industrialized world, according to Matthew J. Eckelman, PhD, an associate professor in the department of civil and environmental engineering at Northeastern University, and colleagues. It produces more than 4% of worldwide greenhouse gas emissions and a similar amount of worldwide toxic air pollutants.

“U.S. health care activities contribute to substantial quantities of environmental emissions and disease burden, contrary to the mission to ‘First do no harm,’” Eckelman and colleagues wrote.

A 2019 Health Care’s Climate Footprint report from Arup and Health Care Without Harm revealed that the U.S. is the world’s greatest emitter of greenhouse gases from health care activities (27%), followed by China (17%). Globally, sources of health care emissions include health care facilities and vehicles (17%), energy sources that power electricity, cooling and heating (12%) and the health care supply chain (71%). Moreover, hospitals alone produce upwards of 5 million tons of waste annually, according to Practice Greenhealth. This total amounts from facilities generating about 29 pounds of waste per hospital bed each day.

There have been some positive changes, however. Findings published in The Journal of Climate Change and Health showed that the increasing use of telehealth services over in-person visits has led to a dramatic decrease in carbon intensity associated with ambulatory visits.

In a retrospective review, Imelda Dacones, MD, FACP, a board member of the Foundation for Medical Excellence, and colleagues reported that in 2020, in-person ambulatory visits declined 46.2% in an integrated health system in the Pacific northwest of the U.S., while transportation-related greenhouse gas emissions decreased by nearly 10 kt CO2-eq. An increase in telehealth appointments cut the carbon intensity of ambulatory visits in half, showing that telehealth can help decrease health care-related emissions.

“Everything from health care centers to smaller hospitals to private practices can have an impact. We could move to more energy-efficient sources such as solar panels in our offices and homes, more efficient heating systems or cooling systems, planting trees, eating well, driving less and using products that we can recycle,” Damle said. “These are small things, but they can all add up when you have many people doing them.”

Dresser agreed that there are several steps physicians can take to make their clinic’s footprint smaller, like switching from single-use to reusable products.

“For a clinician who is concerned about these issues, organizations such as Health Care Without Harm and Practice Greenhealth are actively working to support clinicians in moving their health care institutions toward a sustainable practice pattern,” he told Healio Primary Care.

Freedman also stressed the need to act.

“The challenge remains: how do you get people to act for planetary health? At some point the human health impacts will become so prominent that the pendulum will shift so we can swallow a little easier the pill for planetary health,” Freedman said. “The antidote to climate change is complex, but it will involve redefining some common ways of living, like how we travel, plan our meals, and build our communities. Perhaps a refocus on how investments in planetary health will alleviate pains of insecurity among individuals and communities will grow the momentum needed to begin to tip the system one unit cooler.”


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