Global warming = “meaner” poison ivy

by Caroline Brown

An interesting story from HealthDay reveals that another consequence of global warming is that poison ivy is "getting meaner." A study conducted by researchers from the Marine Biological Institute in Woods Hole, Mass., suggests that the increase of carbon dioxide in the Earth's atmosphere makes poison ivy more abundant and more toxic.

Their study concludes that:

Under atmospheric carbon dioxide (CO2) concentrations that the whole planet will reach by the middle of this century, poison ivy grows not only faster and bigger, but also more poisonous.


In their six-year experiment, Mohan and her colleagues showed that elevated atmospheric carbon dioxide in an intact forest ecosystem increases photosynthesis, water use efficiency, growth and biomass of poison ivy. "This was out in the real world," Mohan said.

Poison ivy plants exposed to elevated CO2 levels averaged 149 percent faster growth compared with control plants, Mohan said. "Something we did not expect to happen, but indeed did — the form of the poison they make was more poisonous," she added.

"This is kind of sad news, not only for humans but for forests," Mohan said. "Increased vine abundance inhibits tree regeneration by killing young trees," she added.

One ecological expert thinks the findings are the first to link increased growth and toxicity with rising levels of CO2.

Anyone who has ever been on the losing end of a poison encounter probably can't imagine that it could be worse, but scientists think that it could:

These experiments predict that poison ivy will likely become more abundant, resulting in more exposures to these dangerous plants, and at the same degree of exposure it is likely to cause worse skin reactions than currently seen, Shaw said. "This is worrisome because of the intense skin reactions that these plants already commonly produce in the majority of the exposed population," he said.

(Note to self: bone up on how to recognize poison ivy.)

Another expert muses about the long-term and far-reaching consequences. This is a "duh" quote if you ask me, but I guess scientists have been saying this for years and no one seems to listen–at least not the people that have the power to do something about it.

"The most worrisome message here is less about this particular plant and more about the whole forest," said Dr. David L. Katz, an associate professor of public health and director of the Prevention Research Center at Yale University School of Medicine.

"We are upsetting a balance in ecosystems and that will have far-reaching effects, many of which we are first now beginning to guess," Katz said.

I have an idea–we should round up all the people who insist that an increase in greenhouse gases doesn't cause problems–along with those** who inexplicably say that it might actually be good for us–strip them down to their birthday suits, and make them roll around in carbon dioxide-enhanced poison ivy!! Heh, one can dream.


** real quotes from the Washington Times article, I DID NOT make these up:

Might it be more sensible to allow a little more pollution to moderate global warming rather than try to stop all CO2 emissions — particularly given CO2 makes vegetation grow faster?


There has been very little serious research to see if benefits of global warming, such as more rainfall, longer growing seasons, healthier climates and extended outdoor sports, will outweigh the costs.

Photo credits: Jon Sachs, The Poison Ivy Site


4 Comments to “Global warming = “meaner” poison ivy”

  1. Yikes. As if poison ivy wasn’t bad enough BEFORE, now it’s becoming WORSE? It is the ‘small’ things like this that make the whole amorphous issue of global warming more REAL for the individual. And ultimately, I think, it’s the “real life” details like that that will cause the majority of people to take it seriously and DO something.

    At least that’s the way I feel today. What the heck, I’m being optimistic.

    Great blog! Thanks for ALL the great info!

    Brad Munson

  2. Thanks for the compliment Brad. I noticed today just how much poison ivy is growing along the walking paths that we normally take. Yikes!

  3. Doh, as you can see, i am kinda allergic to this urushiol oil.

    I really hate it as i have to watch out even on bike path or hicking trails.

  4. Hi Chuck–Your rash is gross! You must be miserable. You should go to the Ivy Block website and enter their contest:

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