Climate Change Endangers Public Health in the United States

The Cancún climate conference has ended with many issues unresolved and U.S. commitments will be hampered by the expected attacks from the incoming Congress on the EPA's authority to regulate greenhouse gases. Meanwhile the urgency for solutions is rapidly increasing and leading medical and public health groups across the country agree: climate change is hazardous to our health.

In the past two decades, extreme heat events have killed tens of thousands around the globe, including populations here in the United States. Heatwaves are more frequent, of longer duration and more intense -- and the lack of nighttime relief accompanying climate change makes today's heat waves all the more lethal. Heat waves can cause illness and death from heart disease, diabetes, stroke, respiratory disease and even accidents, homicide and suicide.

At the same time, increased evaporation arising from warming seas is generating heavier downpours. (The world ocean has accumulated 22 times as much heat as has the atmosphere since the 1950s.) Across the continental U.S., two, four and six inch-a-day rains have increased 14, 20 and 27 percent, respectively, since 1970. This year, sudden, heavy downpours -- some lasting several days -- caused lethal flashfloods in Rhode Island, Tennessee, Arkansas, Oklahoma, Illinois, Iowa, Wisconsin and Minnesota. Rains two inches a day and above are associated with water-borne disease outbreaks, when flooding overwhelms sewer systems and contaminates drinking water.

Increases in winter weather anomalies are emerging. Though winters have become shorter (two-to- three weeks shorter in the Northern Hemisphere, depending on latitude), they have grown more perilous. With warming, more winter precipitation is falling as rain rather than snow, increasing the chance of ice storms when temperatures do drop. Globally, westerly winds are also changing with climate change, affecting the shifts in weather fronts. And such conditions -- along with heavier, wetter snowstorms -- can be treacherous for travel and ambulation. (In Boston, we've dubbed this "orthopedic weather.")

Meanwhile, warmer winters favor insect migration. In the past decade case reports of tick-borne Lyme disease rose ten-fold in Maine and northern counties are experiencing Lyme for the first time. In Alaska, especially warm winters have ushered in swarms of allergy-inducing, stinging insects, along with mosquitoes and devastating pine bark beetle infestations. The spread of forest and crop pests -- requiring chemicals for control -- pose additional long term health and environmental risks.

There's more. Elevated carbon dioxide levels from burning fossil fuels boosts pollen production from ragweed and the pollen grains hitch rides on particulates from diesel and coal combustion, helping to deliver the allergens deep inside our lungs. Meanwhile, the allergy and asthma season has lengthened some two-to-three weeks with climate change, while, since 1980, asthma rates have more than doubled in the U.S.

The American Medical Association is working actively to educate health care professionals about the projected rise in climate-related illness. Medical and public health groups are also taking leading roles in advocating for climate and energy policies, and measures -- like electric vehicles, "smart" grids and healthy cities initiatives -- that will improve public health, create jobs and combat climate change. And physicians and other health care professionals have begun serving as role models for patients by adopting environmentally responsible, energy- and waste-reducing practices in the health sector.

We are deeply concerned that climate instability and changing weather patterns threaten our health and the vitality of our life-support systems. The U.S. must take a leadership role in advancing the clean energy transformation and international climate negotiations over the coming year. The harm to our health and our well-being, and the associated health and social costs, will continue to mount unless we take comprehensive action to stabilize the global climate system.

Cecil B. Wilson, M.D. is President of the American Medical Association and Paul R. Epstein, M.D., M.P.H. is associate director, Center for Health and the Global Environment, Harvard Medical School.