According to the Centers for Disease Control and Prevention, 5 percent to 20 percent of the U.S. population gets the flu each year. Of those, about 200,000 people require hospitalization and 36,000 ultimately die. But imagine if, in addition to the stresses of cold and flu season, American health providers were annually confronted with widespread outbreaks of malaria or a host of other diseases that could spread into the United States due to global warming.

If this sounds like a scenario from a Hollywood thriller, think again.

According to a growing body of research, the threat of global warming bringing new diseases to America's shores is one that U.S. policymakers need to take seriously. As the world warms, diseases are spreading farther, heat waves are lasting longer and air quality is declining. In 2005, the World Health Organization stated that the effects of climate change might have caused more than 150,000 deaths in the year 2000, and unless action were taken soon, succeeding years would likely fare worse. Indeed, a report released this December at a conference of the American Society of Tropical Medicine and Hygiene warned that changing climates, when combined with international air travel, could help spread the scourge of malaria to areas in the United States and Europe that have historically remained untouched.

Every outbreak of disease, or weather phenomena with adverse implications for human health — such as smog — has multiple causes.

We can never say any isolated event stems solely from global warming.

But using that as an excuse for inaction misses the larger point. Many public health threats are closely tied to the climate, and the hotter it is, the more likely these threats become. Global warming pollution, therefore, is stacking the deck against our own health.

Smog, for instance, is caused by the interaction between air pollutants, sunlight and heat. The United States regulates those pollutants leading to smog, but does not directly control the emissions that cause global warming. This ignores a key part of the problem, as rising temperatures are projected to increase U.S. smog-related deaths 4.5 percent by mid-century, with a corresponding jump in asthma attacks, lung damage and cardiac arrest.

Global warming is not just an abstract concern about wildlife at the world's poles. It's also a problem that hits close to home, and health professionals already see warning signs. In an issue devoted largely to global warming, the Journal of the American Medical Association urged, "It is not too late and none too soon for the healthcare community to advocate policies that wean us from fossil fuels and ultimately mitigate the extent of human-induced climate change."

The spread of malaria poses one such problem. According to the WHO, in some countries with a heavy malaria burden the disease can account for as much as 40 percent of public health expenditures. This includes a combination of healthcare costs imposed both on the public (such as through the need for new infrastructure to handle increased medical demands) and directly on individuals and families (through increased personal expenditures on items such as antimalarial drugs).

With the U.S. healthcare system already under tremendous pressure, the additional challenge of global warming is one that our healthcare providers can scarcely afford. Earlier this summer, the Environmental Protection Agency released the most comprehensive analysis to date on the U.S. health problems caused by global warming. That report, which compiled research from dozens of previous studies, found it "very likely" that heat-related morbidity and mortality would increase in the decades ahead, with broad impacts spanning every region of the country.

Nevertheless, even with its latest report in hand, the agency has yet to officially declare whether or not greenhouse gas emissions endanger public health. While the EPA should get some credit for sounding an alarm, the agency hasn't provided any significant steps to address America's unrestrained carbon emissions.

While relaxation in a warmer climate was historically prescribed for colds and a wide range of other ailments, global warming is nobody's cure. The health reports on climate change, from the EPA, CDC and WHO, should provide the stimulus for the next Congress and the Obama administration to enact binding, science-based limits on the emissions that cause global warming.

Phyllis Cuttino is the director of the domestic global warming campaign for the Pew Environment Group. Reach her at pcuttino@pewtrusts.org.