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National Institute of Environmental Health Sciences

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New Report Distills the Science Behind Climate Change Impacts on Health

By Paula T. Whitacre

Earlier this month, the U.S. Global Change Research Program (USGCRP) released a new assessment of the public health threat caused by climate change. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment report has a U.S. focus, but its findings have global implications.

Flyer about the impacts of climate change on human health int he United States

The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment
(Photo courtesy of

“The impacts of climate change on human health interact with underlying health, demographic, and socioeconomic factors,” the report states. “Through the combined influence of these factors, climate change exacerbates some existing health threats and creates new public challenges.”

Building on previous assessments developed by the USGCRP, which coordinates the climate change efforts of 13 federal agencies, the report links health impacts of climate change with the science behind them. A USGCRP working group led by John Balbus, M.D., of NIEHS, Juli Trtanj of the National Oceanic and Atmospheric Administration, and George Luber, Ph.D., of Centers for Disease Control and Prevention, coordinated the effort.

“This assessment not only provides the latest science on questions like how climate change affects our health and who is most vulnerable, it starts to answer the key questions of how much of an impact climate change will have on different health problems and how many people in the U.S. will be affected,” said Balbus.

Global Links

In addition to major US media coverage, outside the U.S., the report received coverage through traditional media, such as in the Times of India, and via Twitter and other social media. "The report is tremendously useful for the international research community and has applications in countries like India despite different national priorities,” noted Rais Akhtar, Ph.D., of the International Institute of Health Management and Research in New Delhi, a lead author in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

The report also complements a global effort by the World Health Organization (WHO) to characterize the health impacts of climate change on a country-by-country basis through health and climate country profiles. Beginning with 15 countries, the profiles provide a snapshot of up-to-date information about current and future impacts of climate change on human health, current policy responses at the country level, and opportunities for health co-benefits from climate mitigation actions.

Health to Center Stage

In releasing the report, U.S. administration officials stressed that human health considerations make it all the more important to address climate change now rather than at some point in the future.

Each chapter highlights three to five key findings and summarizes the supporting scientific evidence for the findings and health impacts. In keeping with its intended use and audience, the report is accessible online and includes infographics and highlights that make it easy to scan and search. Separate chapters cover health impacts related to temperature extremes, poor air quality, extreme events such as hurricanes and droughts, vector-borne diseases, water-related illnesses, and food safety and nutrition. Finally, the report looks at how climate change affects people’s mental health and well-being and discusses populations of concern including children, the elderly, workers, indigenous people, and low-income groups.

The assessment’s findings provide information that can help health care providers, public health officials, and the public better protect health by adapting to climate change impacts. For example, evidence of worsening asthma and allergy conditions or an expansion of tick activity and range could prompt changes in policies, health care protocols, or individual actions to prevent exposures. Health care providers can also recommend specific measures to help protect vulnerable patients, such as people taking medications that make them more sensitive to heat exposure.


Balbus and Kimberly Thigpen Tart, J.D., program analyst in the NIEHS Office of Policy, Planning, and Evaluation, each authored two of the report’s chapters and represented the National Institutes of Health on the assessment’s steering committee.

NIEHS also developed a bibliographic database for use in the literature review conducted by the report authors. The database categorizes the wide body of literature on climate change and health according to factors such as type of study, geographic region studied, and coverage of crosscutting issues such as vulnerable populations or potential health co-benefits. This bibliographic database is being expanded into a searchable, online tool that will be available to the public.

“This assessment report is one part of an ongoing effort by the USGCRP to provide scientists and the public with information, data, indicators, and tools related to climate change in a sustained manner,” explained Balbus. “NIEHS will continue to support this effort by updating its information and data resources, as well as supporting research to add to our understanding.”

To help engage the climate change community in developing tools to better understand potential health impacts of climate change, NIEHS also recently conducted a Climate Change and Environmental Exposures Challenge. The institute challenged participants to produce visualizations, tools, or applications that can help to convey the potential risks of environmental exposures that may be worsened by climate change (see box).

Next Steps

Immediate next steps involve disseminating the assessment and its findings to a wide audience of stakeholders and engaging various groups in thinking about how the assessment can be used to support health protective actions.

“The assessment is impressive, both visually and in terms of painstaking attention to evidence review,” observed Nitish Dogra, M.D., member secretary of the Understanding Climate and Health Associations in India initiative. “Developing countries can learn a great deal from the report. At the same time, for a subsequent edition, the United States could draw upon unexplored areas from international settings like India. As illustrative examples, these include the issues of sea-level rise, migration, and conflict, all not necessarily disconnected."

Indeed, the assessment identifies a number of areas in need of further study, so the working group will engage with researchers in the United States and around the world to encourage research and collaboration that will push our understanding of climate change’s health impacts even further.

Innovations to Help Decision Makers and the Public

One tool identifies areas most vulnerable to combined climate change and air pollution risks. Another maps risks from flooding in a specific neighborhood of Indianapolis. These are some of the innovative data tools and visualizations submitted by participants in the first-ever NIEHS Climate Change and Environmental Exposures Challenge.

Challenge entries were judged on scientific validity, innovation and usability, and clarity of purpose and audience. "The challenge provided an exciting incentive,” said Kimberly Thigpen Tart, who served as one of the judges of the challenge. “By focusing the attention and energy of people across disciplines on creating tools to help identify and support solutions to the health problems posed by climate change.”

The winning submissions are described and accessible on the Challenge website.