Expert Commentary

The 2022 Lancet climate change and health report: Dire warnings and glimmers of hope

The seventh annual report finds climate change is increasingly undermining every pillar of good health and compounding the impact of the COVID-19 pandemic and ongoing conflicts. While mitigation efforts remain inadequate, the report does offer some hope.

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Dr. Renee Salas sees the effects of climate change in the patients she treats in the emergency department at Massachusetts General Hospital.

“Asthma flares, heart attacks, heatstroke, mental health crises; I can put a Band-Aid on these problems but then I send my patients back out into the world,” Salas said during a virtual panel hosted by the American Public Health Association in October. “Prescribing an asthma inhaler isn’t going to fix the cause of an asthma attack for a young boy living next to a highway where cars are producing dangerous pollutants and climate change is driving increases in wildfire smoke pollen and ozone pollution.”

Salas, a Yerby Fellow at the Center for Climate, Health, and the Global Environment at Harvard T.H. Chan School of Public Health, was speaking about the release of the seventh annual Lancet Countdown on Health and Climate Change report on October 25. She’s one of the report’s authors.

The annual report, which is authored by 99 experts from 51 academic institutions and agencies across the world, tracks the impact of climate change on global health. And this year it finds that continued dependence on fossil fuels threatens the health and survival of people around the world.

The report “shows the direst finding yet,” the authors write.  At 1.1 C above pre-industrial levels now, “climate change is increasingly undermining every pillar of good health and compounding the health impacts of the current COVID-19 pandemic and geopolitical conflicts.” Yet, “mitigation efforts remain inadequate to avert a catastrophic temperature rise,” they add.

This year’s report builds on “The 2021 report of the Lancet Countdown on Health and Climate Change: Code Red for a Healthy Future,” which showed that every year, in every region of the world, the impact of a warming climate on human health is getting worse compared with previous years, and that climate change is further exacerbating health inequities.

In his speech in November at the UN climate change conference Framework Convention on Climate Change 27th Conference of the Parties (COP27) in Egypt, UN Secretary-General António Guterres said, “We are on a highway to climate hell with our foot still on the accelerator.”

About the report

The Lancet, a prestigious medical journal founded in 1823, has been publishing the Countdown on Health and Climate Change reports for the past seven years.

The report uses 43 indicators to monitor the association between climate change and health. These indicators explore topics such as the connection between health and heat, extreme weather events like wildfires and drought, the link between climate change and increase in infectious disease transmission, and the impact of climate change on food insecurity. The report also explores climate change policies across countries and the economic impacts of climate change, including the costs of heat-related deaths due to factors such as years of life lost.

Among the new indicators this year are the impact of extreme temperatures on food insecurity, exposure to wildfire smoke, and household air pollution.

The report also has policy briefs for several countries, including the United States.

Global findings, in brief

The 43 indicators in this year’s report are presented in five groups: Health hazards, exposures, and impacts; Adaptation, planning, and resilience for health; Migration actions and health co-benefits; Economics and finance; and Public and political engagement.

Here are some of the global findings:

  • Heat-related deaths increased by 68% between 2000 and 2021.
  • The COVID-19 pandemic not only has impacted health, it also has had an adverse economic effect on small and large-scale investments toward climate action. Nearly 30% of the 798 cities around the world reviewed in the report reduced financing available for climate action in 2021.
  • Warmer coastal waters are welcoming pathogens. The risk of malaria transmission has increased from 1951–60 to 2012–21, and so has the risk of dengue transmission.
  • Dependence on fossil fuels has indirect health effects through climate change, and it has direct health impacts through volatile and unpredictable fossil fuel markets. “Millions of people do not have access to the energy needed to keep their homes at healthy temperatures, preserve food and medication,” the authors write.
  • The health-care sector, including hospitals, is responsible for 5.2% of all global emissions, but 60 countries have committed to low-carbon or net-zero carbon health systems. Meanwhile, insufficient climate change adaptation efforts have left health systems vulnerable to climate-related health hazards, especially after the COVID-19 pandemic, the report finds.
  • When climate change affects people’s livelihoods it also affects their mental health. Climate change can exacerbate conflict and violence and influence people’s decision to migrate. Those who are unable to migrate may feel trapped. “Marginalized and vulnerable populations are often disproportionately affected by mental health impacts related to climate change, which can worsen pre-existing mental health inequalities, especially where health care is inadequate,” the authors write. “Indigenous people may be more strongly affected by climate change-induced ecological breakdown.”

The world is on track to reach 2.4 C to 3.5 C above pre-industrial times by 2100, and there’s a 48% chance that the 1.5 C threshold proposed in the Paris Agreement will be exceeded within the next five years. Geopolitical conflicts and the COVID-19 pandemic have made the 1.5 C threshold less likely to be met, the authors write.

“Current policies put the world on track to catastrophic 2.7 C increase by the end of the century,” they write.

The U.S. report, in brief

As a child, Natasha DeJarnett noticed she couldn’t breathe well when she visited her grandparents, who lived in a different neighborhood from her own.

Years later, through a graduate research project, she discovered that this was because her grandparents lived in an area with poor air quality due to the presence of steel mills, toxic sites, interstates and an airport, recalled DeJarnett, an assistant professor of medicine at the University of Louisville, during an APHA virtual panel. She is the co-lead author of the 2022 U.S. Climate Countdown policy brief, along with Naomi Beyeler. The other authors of the study are Salas, Paige Lester, and Dr. Jeremy Hes.

“The burning of fossil fuels is driving climate change and decreasing the quality of the air that we breathe in,” DeJarnett said during an APHA virtual panel. “Cities that have higher air pollution levels also have higher death rates. In fact, poor air quality is linked with adverse impacts to every major organ system in the body.”

This year’s U.S. policy brief focuses on how air pollution, heat waves, infectious diseases and mental health are hurting people, and everyone is at the risk of experiencing the health impacts of climate change. But health impacts of climate change are not experienced equally, according to the report.

“Structural racism and economic injustice amplify climate change-related health inequities by increasing susceptibility and exposure to climate threats and reducing the adaptive capacity of communities targeted by discriminatory policies,” the authors write.

Heat is the top cause of natural weather-related deaths in the U.S., DeJarnett said.

“This is a great concern because we have an extended and hotter warm season along with heat waves that are longer, more frequent and more intense,” she said.

Heat-related deaths for people over age 65 are estimated to have increased by approximately 74% from 2000-2004 to 2017-2021, the report shows. A total of 3,066 heat-related deaths occurred in the U.S. from 2018 to 2020, according to the report.

Extreme heat can also have adverse physical and mental health impacts on children. High temperatures impair their ability to learn in school and make it harder for kids to safely play outdoors, according to the U.S. policy brief. Extreme heat also increases the odds of poor birth outcomes. For people who work in outdoor settings, it increases the risk of kidney disease.

Climate change creates environmental conditions more conducive to disease transmission, including Vibrio bacteria through water, and lime and West Nile diseases through ticks and other insects.

The 2022 U.S. report also spotlights mental health.

“Susceptibility to the mental health impacts of climate change is higher for communities with close ties to the land, including people living in rural and agricultural areas and Indigenous communities, and for children and young people,” the authors of the brief write. “Systemic stressors, such as economic insecurity and discrimination, can exacerbate climate change threats to mental health and hinder equitable access to protective services and resources.”

“This is a vitally important health outcome, but it’s harder to measure,” said DeJarnett. “There is strong evidence that climate change is associated with more depression, stress, post-traumatic stress disorder and anxiety.”

Other reports have also highlighted the impact of climate change on mental health.

The 2021 report by the American Psychological Association, “Mental Health and Our Changing Climate,” describes the short- and long-term impact of climate change on mental health.

“Heat can fuel mood and anxiety disorders, schizophrenia, vascular dementia, use of emergency mental health services, suicide, interpersonal aggression, and violence,” the report’s authors write. “Drought can lead to stress, anxiety, depression, uncertainty, shame, humiliation, and suicide, particularly amongst farmers.”

The carbon footprint of the American health care system

Of the 37 health systems analyzed individually in the global Lancet report, the U.S. had the most emissions per person — 50 times the emissions from the health care sector in India.

The U.S. health sector is responsible for 8.5 % of the nation’s carbon emissions, according to a 2021 perspective article published in the New England Journal of Medicine.

These emissions stem directly from the operations of health care facilities and indirectly from both purchased sources of energy, heating, and cooling and the supply chain of health care services and goods, according to the article’s authors.

“Ameliorating the sector’s environmental effects and reducing greenhouse-gas emissions could not only improve health for everyone, but also reduce costs of care,” they write.

The National Academy of Medicine has launched the Action Collaborative on Decarbonizing the U.S. Health Sector, a public-private partnership of leaders and organizations from across the health systems, to address the sector’s environmental impact.

“Improving the carbon footprint of the entire health ecosystem can drastically lower the approximately 8.5% of U.S. carbon emissions for which it is responsible, while also having significant health, social, and economic benefits,” according to the collaborative’s website.

The American Medical Association has also added to its existing policy a goal to decarbonize the U.S. health sector, the organization announced on Nov. 15 during its 2022 Interim Meeting.

“Physicians pledge to do no harm, and now it is time for the health sector to do the same by joining forces to commit to decarbonization and public health,” AMA Trustee Drayton Charles Harvey said in a statement posted on the organization’s website.

Glimmers of hope

The report highlights some “emerging glimmers of hope.”

“Although the health sector is responsible for 5·2% of all global emissions, it has shown impressive climate leadership, and 60 countries had committed to transitioning to climate-resilient and/or low-carbon or net-zero carbon health systems as part of the COP26 Health Program, as of July, 2022,” the authors write.

More city leaders are identifying risks of climate change on the health of their populations, “a first step to delivering a tailored response that strengthens local health systems,” the authors write.

And there are signs of change in the energy sector.

“Zero-carbon sources accounted for 80% of investment in electricity generation in 2021, and renewable energies have reached cost parity with fossil fuel energies,” according to the report. “As some of the highest emitting countries attempt to cut their dependence on oil and gas in response to the war in Ukraine and soaring energy prices, many are focusing on increasing renewable energy generation, raising hopes for a health-centered response. However, increased awareness and commitments should be urgently translated into action for hope to turn into reality.”

There’s also more media coverage than ever on the link between climate change and health. The new Lancet report finds in 2021, global newspaper coverage — in print and online — of both climate change and health reached a new record high, with 14,474 articles, 27% more than in 2020.

In 51 English-language newspapers across 24 countries, 20% of 13,017 articles referring to both health and climate change also referred to adaptation measures, and 48% referred to the pandemic. Only 5% referred to health, climate change, adaptation, and the pandemic, according to the report.

Advice for journalists

Climate change affects people’s health and it’s an angle journalists can pursue to engage their readers.

During the APHA briefing, DeJarnett advised journalists to more frequently discuss that angle. “When there is coverage on extreme heat, air quality, wildfires, extreme weather, flooding, drought, etc., I would love to see them highlight the physical and mental health connections,” she said.

In a webinar on Nov. 15, Peter Prengaman, AP’s Global Climate and Environmental News Director, gave journalists three pieces of advice for covering climate change: Don’t be intimidated; think about what is happening in your community — sources of energy, preservation efforts, high electric car sales — and try to connect those things to the larger climate and environment stories; and make your stories about people.

“Start with what people know,” Salas advised in a 2021 interview with The Journalist’s Resource. “I’ve had patients say, ‘My allergies are just so much worse over the past few years,’ or, ‘I just really had a lot more trouble getting my asthma under control,’ or, ‘It’s been so hot I can’t actually go out and run and do the things I want to do.’ I can guarantee that there are multiple ways that climate change is harming health in every region of the U.S. Start there and lead the readers on that path to say here’s what’s happening here.”


  • At The Journalist’s Resource, we have dozens of tip sheets, research roundups and explainers on various aspects of climate change. 
  • Covering Climate Now, an initiative co-founded in 2019 by the Columbia Journalism Review and The Nation in association with The Guardian and WNYC, collaborates with journalists and newsrooms to produce more informed and urgent climate stories, to make climate a part of every beat in the newsroom. The organization also offers best practices for climate reporting.
  • Climate Central is an independent organization of leading scientists and journalists researching and reporting the facts about our changing climate and its impact on the public.
  • World Weather Attribution, an international collaboration provides robust assessments on the role of climate change in the aftermath of extreme weather or climate-related events. 
  • CDC’s Heat & Health Tracker provides local heat and health information so communities can better prepare for and respond to extreme heat events.
  • Climate Reporting Masterclass, a project of Climate Matters in the Newsroom, features climate experts providing journalists with tools, tips and resources for their reporting. 
  • Climate Communication is a nonprofit science and outreach website and information resource, and a project of Aspen Global Change Institute, a nonprofit institute dedicated to furthering the scientific understanding of Earth systems and global environmental change.

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