Study Examines Potential Adverse Health Effects of Climate Change

An examination of the evidence over the past 20 years indicates that climate change can be associated with adverse effects on various health conditions, including heat-related and respiratory disorders, and a projected increase in days with extreme heat could exacerbate various health issues, according to an article published in JAMA. The study is being released early to coincide with the UN Climate Summit 2014. The authors note that substantial health and economic benefits could be associated with reductions in fossil fuel combustion.1

Although uncertainty remains regarding the extent of climate change, this uncertainty is diminishing. Consensus is substantial that human behavior contributes to climate change, caused by activities such as fossil fuel combustion and tropical deforestation. Health is inextricably linked to climate change. It is important for clinicians to understand this relationship in order to discuss associated health risks with their patients and to inform public policy, according to background information in the article.

Jonathan A. Patz, M.D., M.P.H., of the Global Health Institute, University of Wisconsin, Madison, and colleagues conducted a study to provide new U.S.-based temperature projections and to review recent studies on health risks related to climate change and the benefits of efforts to mitigate greenhouse gas emissions. The authors searched the medical literature for articles related to climate change and health, and identified 56 articles that met criteria for inclusion in the analysis. In addition, data were averaged over 13 climate models, and the researchers compared maximum daily 8-hour average ozone with air temperature data taken from the National Oceanic and Atmospheric Administration National Climate Data Center.

Analysis of the data indicated that by 2050, many U.S. cities may experience more frequent extreme heat days. For example, New York and Milwaukee may have 3 times their current average number of days hotter than 90°F, which may exacerbate heat-related disorders, including heat stress and economic consequences of reduced work capacity. In addition, adverse health aspects related to climate change may include:

• Respiratory disorders, including those made worse by fine particular pollutants, such as asthma, and allergic diseases;
• Infectious diseases, including vector-borne diseases (such as transmitted by mosquitos) and water-borne diseases, such as childhood gastrointestinal diseases;
• Food insecurity, including reduced crop yields and an increase in plant diseases;
• Mental health disorders, such as posttraumatic stress disorder and depression, that are associated with natural disasters.

The authors write that substantial health and economic benefits could be associated with reductions in fossil fuel combustion. “Accounting for co-benefits may document that reducing greenhouse emission yields net economic benefits, that labor productivity increases, and that health system costs are reduced. Co-benefits can provide policymakers with additional incentives, beyond those of curtailing climate change, to reduce the emissions of both carbon dioxide and short-lived climate pollutants.”

They add that health professionals have an important role in understanding and communicating potential health concerns related to climate change, as well as the benefits from burning less fossil fuels.

“Because climate change may have important implications for the health of the world’s population, high-quality research must be conducted, and responsible, informed debate needs to continue. However, given that evidence over the past 20 years suggests that climate change can be associated with adverse health outcomes, strategies to reduce climate change and avert the related adverse effects are necessary.”

“Should physicians be concerned about climate change and its associated effects on health or is it outside the remit of medicine much like poverty and war,” write Howard Bauchner, M.D., Editor-in-Chief, JAMA, and Phil B. Fontanarosa, M.D., M.B.A., Executive Editor, JAMA, Chicago, in an accompanying editorial.2

“As physicians have come to recognize that many aspects of daily living affect health, such as working conditions, pollution, education, mental health, and psychosocial aspects of disease, medicine has broadened its research, clinical and policy agendas. Many physicians are now involved in addressing these problems. But is climate change similar to poverty and war, best left to other scientists and politicians, or is it of such fundamental importance — like clean water, clean air and adequate sanitation— that physicians should strive to further clarify the effects of climate change on health, educate themselves and the public, and mount a campaign to ensure that climate change does not lead to an epidemic of eroding health?”

“The great gains in well-being in the 20th century occurred because of the concerted effort to improve the health of entire populations. Today, in the early part of the 21st century, it is critical to recognize that climate change poses the same threat to health as the lack of sanitation, clean water, and pollution did in the early 20th century. Understanding and characterizing this threat and educating the medical community, public, and policy makers are crucial if the health of the world’s population is to continue to improve during the latter half of the 21st century.”


1. doi:10.1001/jama.2014.13186;
2. doi:10.1001/jama.2014.13094;