Lancet Policy Brief: Urgent Action Needed to Address Climate Crisis

Columbia Mailman researchers contribute to a review of research on the extensive health harms of the warming planet

October 25, 2021

The United States must rapidly implement an all-encompassing, evidence-informed response to climate change that prioritizes and optimizes health and equity, according to a policy brief authored by health experts from over 70 leading U.S. institutions, organizations, and centers around the world. The brief, which accompanies The Lancet 2021 Countdown on Health and Climate Changereviews research on the extensive health risks of climate change and proposes policy changes. Three Columbia University Mailman School of Public Health faculty were members of a Working Group of Reviewers who contributed to the document.

“Climate change effects are not just an abstraction, something that will happen years from now. They are happening today and they impact every aspect of our health, from the air we breathe—more smoke, more pollen—to the nutritional quality of the food you eat—less protein. Yet at present, at the federal level, there is almost no funding for studying these health effects. We are stumbling along with a candle, when we need a searchlight to see—and to respond—to these threats,” says Lew Ziska, professor of environmental health sciences and contributor and reviewer of the research.

"Climate change is real and happening now. The good news is that there is a ton that we can do to change the course we are on. The first step is to understand where we are in terms of impacts and our responses—which is the crucial work of The Lancet Countdown. You cannot change what you cannot measure,” says contributor Cecilia Sorensen, associate professor of environmental health sciences and director of the Global Consortium on Climate and Health Education.

“Not only is climate change already impacting health adversely, but it is also impacting health also inequitably. We must recognize that the vulnerable are more severely affected,” said study contributor and reviewer Jeffrey Shaman, professor of environmental health sciences and director of the Climate and Health Program at Columbia Mailman, and senior associate Dean of Faculty Affairs at the Columbia Climate School.

The policy brief shines a light on the inequitable health risks of climate change. It also highlights opportunities to improve health through swift action. It examines three interrelated hazards—extreme heat, drought, and wildfires—to highlight the complexities and nuances of climate change, including how health risks vary, can be unexpectedly broad, and have far-reaching consequences. As one example, the brief notes that the likelihood of dengue spreading through the Aedes aegypti mosquito in the U.S. has steadily increased since the 1950s, with a much greater potential for an outbreak.

Extreme Heat 

  • In 2020, adults over the age of 65 experienced a total of nearly 300 million more days of heatwave exposure in the U.S. compared to the 1986-2005 average baseline, making it the second highest year of exposure recorded since 1986. Infants under one year experienced a total of nearly 22 million more days of heatwave exposure in 2020 with respect to that same baseline. 

  • Policy failures such as historic redlining or weak OSHA regulations disproportionately expose people of color, outdoor workers, incarcerated persons, and those living below the poverty line.


  • Drought compounds exposure to heat, increasing respiratory and infectious disease risks, worsening water quality, and exacerbating mental health issues—particularly in rural areas. 


  • Wildfires in the Western U.S. correlate with hotter temperatures, and the wildfire season has been lengthening. In September 2020, there were 80,000 wildfires, which is 8 times as many as 2001. 

  • Fine participles (PM 2.5) from wildfire smoke may be up to 10 times more harmful to human health than PM2.5 from other sources—especially to children. 

  • Smoke-related health impacts may worsen with distance from the fire, due in part to oxidation, as well as people not recognizing dangerous air quality and failing to change their behavior. 

  • PM2.5 from wildfire smoke raises susceptibility to COVID-19, possibly by allowing the virus to travel greater distances and cause more lung inflammation. 


The authors centered public health equity in developing evidence-informed policy recommendations with the goal of improving health outcomes for marginalized and frontline communities while mitigating the causes of climate change.

  1.  Urgent and equitable economy-wide greenhouse gas emission reductions: Rapidly reduce economy-wide GHG emissions to 57-63% of 2005 levels by 2030, consistent with a 1.5°C national emissions pathway, with at least 40% of investments directed towards improving air quality in under-resourced communities, and a near-zero-emission economy by mid-century. 

  2. Incorporate health-related costs of fossil fuels into the social cost of carbon: U.S. calculations must include these health-related costs to accurately analyze the costs and benefits of policies that contribute to the release of carbon dioxide. 

  3. Rapidly increase funding for health protections: Local, climate-specific health research conducted through multi-sectoral partnerships can directly inform the development, implementation, and evaluation of equitable health-protective actions.