Not only do hikers have to contend with wildfires and out-of-control ticks this year, but now even poison ivy is getting worse. This botanical bother’s increasing severity is yet another effect of climate change.

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Warmer soil and inflated CO2 levels are fattening poison ivy vines, causing them to leaf out robustly — and maybe even make your skin itch more when you come into contact with them. Duke University researchers just published a six-year study describing how poison ivy doubled in size when exposed to high levels of carbon dioxide — levels that scientists predict the atmosphere will see by 2050. Not only are these plants getting bigger, but scientists concluded that urushiol, the oil responsible for poison ivy’s famous allergic reaction, also thrives on CO2.

Related: Dragonflies are losing their color due to climate change

Jacqueline Mohan, an ecology professor at the University of Georgia, has also been studying poison ivy. Her experiment in a 4,000-acre forest in Massachusetts managed by Harvard University is still in the early stages, but she suspects that rising soil temperatures are also a boon to the poisonous plant. Her preliminary results indicate that a 9-degree Fahrenheit increase in soil temperature could accelerate poison ivy growth by 149%. “That’s just incredible,” Mohan said, as reported by Grist. “Poison ivy might love soil warming even more than it loves CO2.”

Not worried yet? Unfortunately, poison ivy also loves human disturbance. Clear land for a picnic table, campsite or trail, and poison ivy is one of the first plants to take hold. It loves sunlight and prefers to grow in spots with few other plants.

So, when you go for a hike, look out for those three-leaf clusters and veer away. Wear long pants. Pay attention. According to the Forest Service, 70-85% of the population is sensitive to urushiol and likely to become more allergic with increased exposure. “When you’re dealing with nature, be smart,” said Mohan. “Because nature is always going to win.”

Via Grist

Lead image via Pixabay