by Kim Krisberg

With the world’s top scientists declaring human behavior at the root of global warming and new warnings that work must begin now to prevent its catastrophic effects, climate change has firmly cemented its place on the international stage.

The complex causes of climate change and the domino effects of rising global temperatures are predicted to have direct consequences on people’s health and lives. The effects could range from the deadly — such as hurricanes and heatwaves — to the less serious — such as when warmer air and higher concentrations of carbon dioxide spur increased ragweed pollen production. The good news, though, is that people can help mitigate the effects of global warming by changing how they interact with their environments, and public health workers will be key in driving that message home.

Jonathan Chan raises his arms in a Greenpeace event protesting global warming at a beach in Dania, Fla., in November. The event drew attention to rising sea levels along the U.S. coast.  Photo by Roberto Schmidt, courtesy Getty Images

MD, DrPH, director of the National Center for Environmental Health at the Centers for Disease Control and Prevention. "This ought to become a very important priority for public health."

Armed with clear and compelling science, public health is just one of the many sectors with a role to play. In February, the United Nations Intergovernmental Panel on Climate Change released its fourth assessment report, finding it very likely that "global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change" and that global warming is "unequivocal." A few weeks after the panel’s report, the United Nations Foundation released a "roadmap" for mitigating and adapting to climate change, calling on world policy-makers to immediately act to reduce greenhouse gas emissions — a cause of global warming — by improving vehicle efficiency and building design and investing in cleaner energy. The road-map also calls on communities to improve prepared- ness efforts to "adapt to ongoing and unavoidable changes in the Earth’s climate system," drawing specific attention to the poorest and most vulnerable nations, which are the least offending nations in terms of emissions but whose populations could bear the brunt of global warming.

CDC is now bringing together experts to help the agency chart its course on climate change, Frumkin said, and CDC Director Julie Gerberding, MD, MPH, has committed to making climate change an agency priority. Fortunately, many conventional public health activities can be used to help mitigate and study global warming, and the recommendations proposed to fight global warming will also address priority public health problems, such as obesity and low physical activity rates, Frumkin told The Nation’s Health. Specifically, public health work to create healthier built environments — which encompasses all of the man-made structures that constitute a person’s living space, from housing developments to parks to roads — targets the same behaviors and lifestyles that contribute to global warming.

"There is a very promising overlap between built environment issues and climate change issues," Frumkin said. "As we better understand how to create healthier communities, the same interventions that promote health will also protect the public from climate change."

For example, he said, community designs that feature low-density land use and wide distances between destinations mean people are more dependent on cars, leading to more sedentary lifestyles and added greenhouse gas emissions from vehicles. In cities, trees and foliage are replaced with black asphalt surfaces and concrete buildings, both of which retain heat and make cities warmer than their surrounding countrysides. The result is called the "urban heat island effect," Frumkin said. Climate change is expected to exacerbate the problem and in turn, city residents’ health will be more threatened.

"We absolutely have to consider the design of our built environment," said Jonathan Patz, MD, MPH, associate professor in the Nelson Institute’s Center for Sustainability and the Global Environment as well as the Department of Population Health Sciences at the University of Wisconsin-Madison. "Urban design and global warming policy go hand in hand and they’re both good public health policy as well."

Patz, who co-authored a 2004 Journal of the American Medical Association article on climate change and health, said that while climatologists can’t easily link specific extreme weather events to long-term climate changes, the frequency and intensity of weather disasters is consistent with global warming predictions. Also, much of what is understood of global warming health effects comes from past experiences, he said. Patz led a study on water-borne disease outbreaks in the United States between 1948 and 1994 and found that two-thirds of such outbreaks were preceded by very heavy rainfalls — a weather event predicted to increase with continued global warming. Already, almost 1,000 U.S. communities depend on infrastructures that combine storm water runoff and sewage, with more than 1 trillion gallons of sewage and run-off contaminating surface water — and potentially drinking water — annually due to heavy rainfalls, Patz told The Nation’s Health.

Health risks of climate change varied, dire

Another side effect of climate change could be an increase in vector-borne diseases. In a mosquito, a "half of a degree in temperature could mean the difference between that mosquito being infectious or not infectious," Patz said. For example, while global warming didn’t bring West Nile virus to the United States, when the disease hit New York City in 1999, it was the city’s hottest July ever recorded. New analyses have shown that such extreme heat could have helped the virus take a foothold in the United States, Patz said. Climate change has also been studied in relation to weather disasters such as tsunamis and hurricanes, with the number of Category 4 and 5 hurricanes increasing in step with warming sea surface temperatures.

Children walk along the banks of the Arctic Ocean in Alaskain June 2006. Large areas of the Arctic Ocean could lose year-round ice cover by the end of the century if human emissions continue to increase, a new U.N. report predicts. Photo by Justin Sullivan, courtesy Getty Images.

Many advocates are optimistic that the time to address global warming has come, pointing to the unlikely convergence of stakeholders committed to fighting the issue, such as partnerships between environmental advocates and industry. New legislation in Congress on greenhouse gas emissions and plans by House Speaker Nancy Pelosi, D-Calif., to create a Select Committee on Energy Independence and Global Warming are also positive signs. John Balbus, MD, MPH, director of the Environmental Health Program at Environmental Defense, an organizational member of the recently formed United States Climate Action Partnership, noted that while state and local governments can and will have an impact on the global warming debate, it will take federal policy to produce substantial reductions in greenhouse gases. Public health workers will play

a crucial role by helping populations adapt to climate change and articulating why mitigating global warming is good for health, he said.

"Even though it’s not purely a public health issue, I do think the public health community has a critical voice," said Balbus, a member of APHA’s Environment Section. "APHA has a real opportunity to step into the leadership role in communicating with the public and with policy-makers about the public health need to start taking strong action."

For more information, visit www.cdc.gov/nceh or www.ipcc.ch.

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