Experts: Global Warming Could Harm Health

The potential dangers for the planet posed by global warming are well known.

But what about possible health effects on individuals? Is there cause for concern?

"A lot of scientists certainly think so," said The Early Show health correspondent Dr. Emily Senay Monday.

The United States Department of Agriculture estimates that the amount of ragweed pollen, the stuff that causes hay fever symptoms, may have doubled over the past 40 or 50 years. Why? Scientists say the same carbon dioxide involved in global warming also started helping plants produce more pollen during their reproduction processes.

A government researcher recently reported that additional carbon dioxide pumped into the atmosphere has also made poison ivy plants larger, and the oil on the leaves that irritates the skin more potent. So, those three-leafed clusters at the edges of forests may itch longer, and contact that might not have triggered a skin reaction decades ago is more likely to now.

"So," Senay observed, "we're starting to see the health effects of global warming."

And carbon dioxide isn't the only air pollutant that might cause trouble.

It's also likely, Senay says, that ozone levels close enough to the ground for us to breathe (as opposed to the type of ozone in the upper-levels of the atmosphere, which protect the Earth) are increasing. According to a report put out by Johns Hopkins' Bloomberg School of Public Health, ozone at or near ground-level can damage lung tissue, reduce lung function, and make the respiratory tract more sensitive to other irritants. They include particulates in the air, which can aggravate conditions such as asthma, and even increase a person's risk of cancer.

And global warming's impact could even extend to water's ability to spread disease.

The Union of Concerned Scientists suggests it does, Senay points out. Changes in drought and flood patterns may increase the presence of waterborne pathogens including parasites, which can cause severe digestive problems if we swallow them. Diseases carried by insects such as mosquitoes may be spread more widely if rainfall patterns that influence their movement and breeding are altered, as some experts predict. There's no proof yet, but the Union of Concerned Scientists says prolonged heat around the Great Lakes region helped trigger outbreaks of St. Louis encephalitis in that Great Lakes area.

Another ill effect of extra heat could come in the form of food-borne illnesses. We know that high temperatures can turn food into a breeding ground for dangerous bacteria. The more warm weather there is, the greater the chance that food will become contaminated and make us sick.

Which brings Senay to the impact of heat itself on us?

She says all the harmful things heat can do to us may only intensify if temperatures rise. The Centers for Disease Control and Prevention reminds us that heat-related illnesses are especially troublesome for the very old, the very young, and people who exercise too hard and too long in hot conditions. Researchers at Johns Hopkins predict the greatest increase in heat-related deaths in cities in the Midwest and Northeast, where extreme heat is now relatively sporadic, but could become more consistent and dangerous.

There is, however, a bit of a silver lining connected to added heat. If it means milder winters, the World Health Organization says fewer people may die of winter's cold.

But, on balance, Senay concludes, experts expect climate change will hurt our health more than it will help.