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JAMA Forum Archive, 2012-2019: Health policy commentary from leaders in the field
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Private and Public Sector Responses to Climate Change

Three developments in late 2017 heightened attention to the critical intersection between science, climate change, and health:

Image: ChrisGorgio/Thinkstock

  • The US Global Change Research Program’s Fourth National Climate Assessment (NCA4) identified the last 3 years as the warmest in modern history, with human activities related to greenhouse gas emissions (carbon dioxide, methane, hydrofluorocarbons) extremely likely to be the dominant cause. The NCA4, the authoritative assessment from the nation’s leading climate scientists, found no convincing alternative explanation for such warming.

  • Leaders from nearly 200 countries met at the United Nations Framework Convention on Climate Change 23rd Conference of the Parties (COP23) to advance guidelines and procedures for implementing the 2015 Paris Agreement pledges to collectively limit global warming to 2oC (3.6oF) higher than preindustrial levels by 2025. Of note, COP23 took place during a season of extreme US weather events. These included Hurricanes Harvey and Maria (ranked as the second and third costliest tropical cyclones ever recorded) and the 2017 California wildfires (the costliest wildfire event on record).

  • The Lancet Countdown on health and climate change urged the global health community to shift away from 25 years of inaction, pledging to report regularly on health outcomes related to Paris Agreement commitments. Because US health care activities contribute substantially greenhouse gas emissions (resulting in nearly 10% of greenhouse gas emissions in 2013), more research should focus on detecting and attributing the health effects of climate change. A 2017 modelling analysis, part of evolving scientific studies in this area, provides early evidence that the carbon footprint of US health care activities can be linked to 123 000 to 381 000 disability-adjusted life-years lost annually from 5 factors affecting health (malaria, floods, malnutrition, diarrhea, and cardiovascular disease).

All these developments heighten urgency for climate change action, including decreasing reliance on carbon-intense fuels, reducing energy consumption, and improving fuel economy. As the US government has announced its intention to withdraw from the Paris Agreement by November 2020, private and nonfederal public-sector leaders are striving to reduce greenhouse gas emissions 26% below 2005 levels by 2025.

Health Systems and Hospitals

A global effort, the 2020 Healthcare Climate Challenge, involves 160 participants representing more than 14 000 health institutions in 24 countries. Many US health systems and hospitals are contributing to such efforts through partnerships with organizations such as the American Hospital Association, US Environmental Protection Agency, and American Nurses Association. For example, Health Care Without Harm urges health professionals and systems to adopt more sustainable and efficient energy sources and has collaborated with about 1600 hospitals to adopt best practices (in areas that include ventilation, heating, cooling, and lighting). Practice Green Health advocates tracking progress in reducing health care facility–related pollution through 6 challenge areas (including engaged leadership, healthier food, and less waste).

In one prominent example of energy independence, which included interventions involving wind turbine sites, solar projects, a biomass boiler, and a geothermal heat pump, the La Crosse, Wisconsin–based Gundersen Health System in 2014 became the world’s first health system to produce more power than it consumed.

The newly formed Medical Society Consortium on Climate and Health, representing 21 medical societies that collectively comprise more than half of US physicians, emphasizes that clinicians and health professionals can serve as trusted leaders in addressing climate change. In particular, physicians can effectively communicate the health effects that disproportionately burden vulnerable populations through heat-related disorders, respiratory problems related to air pollution, vector-borne infectious diseases, flooding-related waterborne illness, and mental health sequelae from natural disasters.


Motivated by market forces, external accountability standards, and shareholder pressure, businesses are increasingly weaving clean energy strategies into operations. For example, in a well-publicized 2017 annual meeting, shareholders pushed Exxon Mobil to report measures limiting climate change to 2oC. About 125 companies, including Walmart and Bloomberg, have pledged to procure 100% of their energy from renewable resources by 2025. More than 40 US supermarket chains have committed to reducing hydrofluorocarbons used in refrigeration.

More than 200 Fortune 500 companies (43%) have begun implementing strategies to reach targets for sustainability or renewable energy. And although the US economy grew by 15% from 2005 to 2015, net greenhouse gas emissions declined by 11.5%, mostly due to shifts from coal to natural gas. “Greener” power plants, based on gas-fired and renewable energy technology, are increasingly replacing coal-fired ones.

States and Cities

The US Climate Alliance, a bipartisan coalition of 16 states (and Puerto Rico) representing more than 40% of the US population, collaborates on a broad range of greenhouse projects, including updating electric grids for wind and solar power and facilitating electric vehicles. They have also committed to mapping risks and strengthening resilience to climate change–related natural disasters.

Another collaboration, the Regional Greenhouse Gas Initiative, features 9 Eastern states that leveraged cap-and-trade strategies from 2009 through 2015 to cut power plant–related greenhouse gas emissions nearly in half with plans to reduce the emissions cap another 30% by 2030—65% lower than the 2009 starting cap.

Individual states committing to renewable energy sources include Texas, Oklahoma, and Iowa, the nation’s leading producers of wind energy. Texas and Iowa lead the nation in biodiesel production. Other notable contributions have come from California, which recently extended its cap-and-trade emissions program and aims to place 5 million zero-emission vehicles on the roads by 2030; Washington State, and New York. Meanwhile, the US Conference of Mayors, a large bipartisan organization, supports the goal of 100% renewable energy in cities nationwide by 2035.

Next Steps

America’s Pledge, an initiative that aggregates and quantifies the actions of US states, cities, and businesses to lower greenhouse gas emissions, recently reported that half the US economy and population has declared their support for Paris Agreement goals. With NCA4 highlighting the scientific urgency for action, the United States is stepping up through commitments from the private and the nonfederal public sectors. The health sector, which has long recognized that environmental change usually arises from the bottom up, can further accelerate these actions for the benefit of the planet.

About the authors:
Howard K. Koh, MD, MPH, is the Harvey V. Fineberg professor of the practice of public health leadership at the Harvard T. H. Chan School of Public Health and the Harvard Kennedy School. He is also the former Massachusetts commissioner of public health and the 14th assistant secretary for health for the US Department of Health and Human Services. Dr Koh has earned board certification in internal medicine, hematology, medical oncology, and dermatology, and has published more than 250 articles in the medical and public health literature, earned more than 70 awards for interdisciplinary achievements in public health, and has received 5 honorary doctorate degrees. (Image: Harvard T.H. Chan School of Public Health)
Gina McCarthy, MS, served as administrator of the US Environmental Protection Agency under President Barack Obama as the nation’s leading advocate to protect public health and the environment, including initiatives at the federal, state, and local levels to take action on climate change. McCarthy currently serves as professor of the practice at Harvard’s T. H. Chan School of Public Health with a joint appointment at The Kennedy School of Government. She is  Director of Harvard Chan’s Center for Health and the Global Environment, focused on the intersection of climate, health, and sustainability, and serves as an advisor to Pegasus Capital Advisors, a private equity firm focused on sustainability and wellness investments. (Image: Credit: US Environmental Protection Agency)
Any references to a business, product, or service do not represent endorsement on the part of the authors.
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