Bolstered by mild winters and heavy spring rains, the poison ivy creeping across the Chicago landscape this summer is at bumper crop levels.
The abundance of poison ivy and other invasive plants proliferating in Illinois and across much of the nation this year is a symptom of a scenario more serious than an itchy red rash, experts say.
Elevated CO2 levels in the atmosphere, although destructive to many plant species, are proving a boon for adaptive weeds such as poison ivy, said Lewis Ziska, a federal plant physiologist.
"We are up to our arms in poison ivy this summer," said Ziska, with the USDA's Agricultural Research Service in Beltsville, Md.in Chicago Tribune
The higher CO2 levels, he said, also are contributing to an increasing abundance of kudzu, the legendary vine once limited to the South but was discovered lurking in central Illinois and as far north as Canada.
Dr. Paul Epstein, associate director for the Center for Health and the Global Environment at Harvard Medical School, said recent studies show that poison ivy is not only more prevalent across the U.S. but more toxic, too. The rise in CO2 levels strengthens an oil in the plant that triggers itchy havoc when it touches the skin, he said.
The heavy rains, warmer temperatures and rising CO2 levels that have disturbed plant chemistry also have increased pollen counts, leading to higher rates of asthma and allergies.
"It's not an accident we're having this perfect storm," said Epstein. "Pests and pathogens thrive in extreme events, like floods or droughts. We need to stabilize the climate by reducing fossil fuel emissions dramatically."
