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Poison ivy getting larger and more potent

Published On: Jul 24 2013 02:46:22 PM EDT   Updated On: Jul 25 2013 01:05:19 AM EDT
Poison Ivy getting stronger

Photo: Steven Greenspan

The old saying “leaves of three, let it be” may soon be changing as poison ivy sprouts additional leaves due to increased CO2. 

More carbon dioxide (CO2) in our Earth’s system contributes to a warmer world. But is the additional CO2 also making the planet itchier? Probably. Research suggests that poison ivy gets bigger, itchier, and can even change form with increased CO2 levels. That’s disturbing news for the thousands of Americans each year that get the debilitating rash.

What causes the rash is something called urushiol, an oily toxin that inflames human skin on contact. All parts of the plant contain this oil, which can stay potent on almost any material for up to five years.  The graphic to the left shows the amount of oil produced under different CO2 scenarios - following the rise from 1950 to today and continuing into the future as CO2 emissions are expected to continue to rise.

A 2007 study found that both the toxicity of urushiol and the size of poison ivy leaves increased when plants were exposed to greater amounts of CO2. 

Steven Greenspan, a horticulturalist with Poison Ivy Removal, who has more than 45 years of experience, notes that 10 years ago, poison ivy leaves measured 2-4 inches in diameter.

Now it’s not uncommon to find leaves 12-17 inches in diameter. As if that weren’t bad enough, Greenspan expects occurrences of “mutant poison ivy plants” with more leaves and larger vines to increase as more CO2 is emitted.

*Information for this story provided by Climate Central