Climate Corner: Just itching to address climate change

Jul 16, 2022

Linda Eve Seth

“Late at night while you’re sleeping, poison ivy comes a-creeping…” — Lieber and Stoller 1959


Unless you are as old as I am, you might not recognize the song remnant sung by “The Coasters;” but you will recognize that few things can spoil a day outdoors faster than poison ivy. The plant, which presents as a three-leafed vine, can prompt a rash as a reaction to urushiol, an irritating oil in its leaves.

It turns out climate change may not just be making the planet hotter: it seems to be worsening poison ivy, too. Current research suggests that poison ivy may be growing faster and larger due to rising heat and elevated carbon dioxide levels in the atmosphere, and the situation is likely to get worse.

Studies done over the past 15+ years suggest that rising CO2 levels are helping every hiker’s least favorite plant grow faster, bigger, and itchier. As carbon dioxide levels in the atmosphere continue to increase, so does more irritating and pervasive poison ivy (and poison oak). Increasing temperatures, along with rising CO2 levels, are causing poison ivy plants to grow larger and stronger. This results in the plants growing bigger leaves; pie-plate sized leaves are now common

The plant is also benefiting from warmer soils. One experiment from Harvard University demonstrated an increase of 9∂F in soil temperature resulted in poison ivy growing 149% faster. The growth rate of the poison ivy plant has doubled in the last 50 years.

“The chances of encountering poison ivy and coming down with a rash are greater than they used to be,” according to the online site, WebMD.

Additionally, the oil itself that causes poison ivy rash is getting more powerful, according to scientists. Plants raised in a high-CO2 environment produced a more allergenic form of urushiol, the substance that causes rashes in most people exposed to the plant. A generation of supercharged poison ivy should be concerning for humans who react to the plant, which is most (85%) of us. But it’s also likely to impact nearby flora and fauna. Since not all plants respond to CO2 like poison ivy does, it’s possible that growing vines could cause an imbalance in natural ecosystems, choking out more benign plants. Poison ivy is choking trees and filling the border edges of woodlands.

Next to crop failure, deadly heat waves, sea level rise … more poison ivy may seem like a relatively trivial effect of climate change. But for those of us who love to hike, the future may involve a lot more anti-itch lotion than we’d prefer.

What you need to know before you head out to the woods, or the backyard:

It’s been a hot summer locally in the Mid-Ohio Valley. It’s hard to imagine wanting to hike in long pants. But if you live somewhere poison ivy is rampant, you might not have a choice. If you’re into hiking, try to wear long pants and long sleeves rather than shorts and t-shirts and definitely wear socks.

Be sure to learn to identify poison ivy. In addition to having three leaves, it can also appear as a scruffy vine on trees. If a plant you think might be poison ivy has thorns or clusters of five leaves, it’s probably something else.

The offending substance, urushiol, is found in the sap. Burning poison ivy plants can release urushiol particles into the air. The urushiol found in the sap of the poison ivy plant binds to skin cells when it comes into contact. Touching the sap of the plant as well as touching something on which urushiol is present, such as garden tools or a pet who has run through the leaves, can cause the allergic reaction. Shower within a half-hour of contact and you’ll be generally OK. But once it is absorbed, there is not much you can do.

If you normally pack one bottle of anti-itch cream for a camping trip, from now on, consider taking two.

Until next time, be kind to your Mother Earth.


Linda Eve Seth, SLP, M.Ed. is a mother, grandmother, concerned citizen and member of MOVCA.