AAAS Briefing: Climate Change Already Affecting Public Health; Tools Needed to Respond

Policymakers should support efforts to predict and respond to public health challenges—from deadly heat waves to the spread of infectious bacteria—driven by global climate change, a panel of experts said at a AAAS briefing on Capitol Hill.

Some scientific tools are already in place to track disease outbreaks and natural disasters and their links to climate change, the researchers said, but the United States and other countries lack an organized approach that would use these tools to shape public health planning.

Rita Colwell

“We are in a period of time now when climate change is occurring and there will be human effects,” said Rita Colwell, an infectious disease expert and former AAAS president who spoke at the event. “There will be in fact predictable effects, if we are able to marshal the capabilities of modern tools” to study them, she said.

But the United States lacks a plan to gather the necessary “environmental intelligence” to guide policy on this issue, said Science Editor-in-Chief Bruce Alberts, quoting from a recent Science editorial by Eric Barron, head of the National Center for Atmospheric Research.

Bruce Alberts

Alberts was the moderator for the 16 November briefing, which was sponsored by the University Corporation for Atmospheric Research and AAAS, and hosted by the office of U.S. Senator Jim Webb (D-Virginia.).

“As domestic and international negotiations are taking place to mitigate climate change, it is important to highlight some of the impacts of climate change that are already occurring and discuss adaptation options,” said Kasey White, senior program associate with the AAAS Center for Science, Technology and Congress, which helped organized the briefing.

The briefing speakers cited the recent report by the U.S. Global Change Research Program and similar studies that project increases in the prevalence of infectious disease, greater air pollution, and injuries and deaths related to extreme weather and natural disasters such as hurricanes.

Climate change has already brought new disease patterns to the Western Hemisphere, said Mary Hayden, a scientist with the National Center for Atmospheric Research. The mosquito-borne dengue hemorrhagic fever has spread rapidly from the tropics of South and Central America as temperatures warm and the mosquitoes extend their range northward. There has been a 600% increase in dengue cases in Mexico since 2001, Hayden said. In 2005, she and other researchers investigated an outbreak in the Texas border town of Brownsville, documenting the first cases of dengue hemorrhagic fever acquired in the United States.

Mary Hayden

Although global climate models can predict the spread of a disease like dengue, Hayden noted, they may not be as useful for tracking the disease at the local level. “We also need to know about small-scale differences in temperature and rainfall, and changes in human behavior and changes in landscape use.”

Satellite data, genetic sequencing, and other scientific tools can help track outbreaks at the local level, said Colwell, a professor at the University of Maryland and the Johns Hopkins University Bloomberg School of Public Health. In the early 1990s, she noted, researchers working in the southwestern U.S. predicted the risk of hantavirus outbreaks, using satellites to measure increases in vegetation that led to a population explosion of virus-carrying mice.

She has used similar satellite techniques to track blooms of ocean plankton, which harbor deadly cholera bacteria. The satellite data, combined with measurements of sea surface temperature and sea level, have helped Colwell and colleagues predict the timing and strength of cholera outbreaks in Bangladesh and other vulnerable coastal countries.

“It’s the very strong, science-based, simple solutions,” she said, “and it is the information that we can gain by the tools of science that will allow us to respond” to such public health emergencies.

Lynn Goldman

Attention to climate change has also brought greater scrutiny to the health consequences of energy choices, said Lynn Goldman, a professor of environmental health sciences at the Johns Hopkins University Bloomberg School of Public Health. Increasingly, she said, researchers are examining how different fuel sources such as coal and oil can affect health.

“Using more energy is associated with improvements in health, like longer life expectancy and lower infant mortality,” said Goldman, “but then there’s a turning point beyond which we continue to consume more and more but it actually isn’t improving our health.”

Becky Ham

4 January 2010