Climate Change: Bad News on the Health Front

by Bill Chameides | October 15th, 2008
posted by Erica Rowell (Editor)

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When it comes to environmental pollution, people tend to care most about health effects. Three new studies on how global warming is affecting health will not be welcome news to these folks.

On the surface it’s difficult to see how seemingly small changes in global temperatures can come back to bite us in so many ways. Perhaps language plays a small part — scientists say “global warming” but we really mean climate disruption (see earlier post). Greenhouse gas pollution is profoundly changing the climate system and the impacts are proving to be wide-ranging and often worrisome. Perhaps most worrisome and closest to home are risks to human health.

Understanding how global warming will affect health and disease is critical, because that understanding will arm public health officials with the knowledge from which to create mitigation and response plans. Several studies released last week have added to the growing knowledge base. The American Journal of Preventive Medicine’s November issue focuses on the intersection of climate change and health. I am going to review two of those papers, as well as another one from Gephysical Research Letters.

Heat Waves Are a Major Threat

Here’s a fact that may surprise you: heat waves cause more deaths in the United States than any other type of extreme weather event. According to the Centers for Disease Control (CDC) more Americans “died from extreme heat than from hurricanes, lightning, tornadoes, floods, and earthquakes combined.”

A new paper by George Luber and Michael McGeehin, of the National Center for Environmental Health at the CDC, examines how the intersection of climate change and extreme heat events affects human mortality.

The group likely to be hardest hit by more intense, frequent extreme heat events, they find, are aging populations in Northeastern and Midwestern cities. Why? These areas are unaccustomed to coping with heat on a regular basis, and some preventative measures taken during milder heat waves are counterproductive at higher temperatures. For example, using fans for cooling actually increases heat stress when ambient temperatures are above normal body temperature (99 degrees Farenheit). Already, between 1949 and 1995, areas in both the western and eastern parts of the United States have experienced a 20 percent increase in the number of heat waves.

The authors offer up a range of options to mitigate this aspect of climate change. In addition to steps individuals can take (such as avoiding exercise and staying hydrated during heat waves), their strategies include the development of a detailed Health Response Plan by public health agencies and the design and development of “cool cities.”

Water Pollution

Mitigation is also the focus of a study (by Jonathan Patz and colleagues at the University of Wisconsin-Madison) that examines climate change and the risk of waterborne disease. Deluges and other extreme rainfall events can overwhelm municipal sewer systems. And so the resulting floods can contain toxic bacteria, parasites and viruses, such as E.coli and cryptosporidium. (See here and here.)

Merely coming into contact with that water, let alone drinking it, can cause serious harm. In fact, earlier work by Patz and others found that two thirds of U.S. waterborne disease outbreaks between 1948 and 1994 were correlated with heavy rainfall.

In addition to rising temperatures, global warming puts more water vapor in the atmosphere. As a result, rains in a warmer world are expected to be more intense. In fact, rainfall data show that this intensity is already on the rise (see my earlier post). Patz and his colleagues urge governments to prepare for the coming deluges by, for example, renovating and upgrading crumbling, undersized sewer systems that typically handle both raw sewage and storm water.

Wildfires and Air Pollution

When most people think about air pollution, they don’t think wildfires. After all, people tend to think of air pollution as an urban problem and wildfires confined to rural, wooded America. Not so. The atmosphere does not recognize boundaries between cities and forests. Smoke and related air pollutants produced in wildfires can be carried by the winds over hundreds and thousands of miles, much like the pollution normally associated with urban areas – from industry, power plants, and transportation. When pollution from wildfires travels and meets up with pollution spewed from cities and industry, the result is often a noxious mixture of not-so-fresh air to breathe — and often in rural areas not usually associated with poor air quality.

Gail Pfister and fellow researchers at the National Center for Atmospheric Research studied the 2007 fall wildfire season in California. They found that intense wildfires increased the concentrations of ground-level ozone, a major component of smog. This increase in surface ozone was often significant enough to push it above the government levels designed to protect human health. Often these effects are felt far from where the fire blazed.

So what is the climate connection? There’s a strong link between the rising frequency of wildfires in the American West and rising temperatures (see here). We have known for some time that global warming will exacerbate smog produced by the usual suspects – pollution from industry, power plants, transportation. This new study adds another source to that list: wildfires.

Act Now, Adapt Now

Mitigating global warming (by reducing the rates at which carbon dioxide and other greenhouse gases are spewed into the atmosphere) is key to healthy development of the planet. These new studies highlight the need for a complementary effort – adaptation to global warming to minimize its inevitable impacts. Our health may be in the balance.

filed under: climate change, faculty, global warming, health, heat waves
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