Poison ivy: everyone’s favorite Batman villain and nature’s worst toilet paper. And now it’s getting a whole lot more sinister, thanks to our carbon emissions. In a sick karmic twist, the massive CO2 our buildings and cars belch is catnip for poison ivy, making the plants grow faster and bigger:

Higher CO2 benefits plant growth but especially poison ivy. Pie-pan sized leaves now are common. Poison ivy is choking trees and filling the edge of woodlands.

Lewis H. Ziska, a research weed ecologist with the U.S. Department of Agriculture, said laboratory and field studies show that poison ivy is advancing with climate change. That trend will continue as carbon dioxide levels keep rising from the current average level of about 400 parts per million to 560 ppm or higher in the next 30 to 50 years, with predicted levels reaching 800 ppm by century’s end, he said.

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Already poison ivy’s growth and potency has doubled since the 1960s, and it could double again once CO2 levels reach the 560 ppm mark, Mr. Ziska said. … “In the last 50 years, the growth rate of poison ivy plant already has doubled.”

Tens of millions of Americans get poison ivy annually, and it can last up to six weeks. In South Carolina’s coastal plain forests, few plants are thriving except for poison ivy, which is “getting happier and nastier.” (Shudder.)

No one is a bigger fan of poison ivy than Grist’s lovable curmudgeon/climate-‘n’-energy wizard, David Roberts, who recently fell in love with the plant on vacation. Now for Dave’s Poison Ivy: Greatest Hits!

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Send Dave your love and steroids: @drgrist

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