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Is carbon dioxide all that it’s cracked up to be?

August 5, 2011 | 7:20 pm | , Science and Solutions Director

Source: © 2006 NDSU Ag Communications

Stop me if you’ve heard this one before: carbon dioxide is good for plants, and therefore it doesn’t count as pollution. That’s not a joke. It’s one of the 50 most commonly used arguments against taking action to reduce warming pollution in our atmosphere.

It’s true that plants need carbon to survive, and that many plants grow more quickly when they are exposed to higher concentrations of carbon dioxide. But now we’re pumping billions of tons of carbon into the atmosphere every year — 9.5 billion tons in 2009 alone. Could there be unintended consequences to all this extra plant food? Early signs point to yes.

For example, new research from China suggests that wheat and rice grown in a high-carbon environment take up more cadmium from the soil. Cadmium is a toxic heavy metal that can harm our kidneys and bones. The U.S. Global Change Research Program reports that some crops grow larger when they are exposed to more carbon, but that they have a lower nutritional content than their low-carbon counterparts. And it turns out that crops aren’t the only plants that can benefit from extra carbon. Hikers, gardeners and hunters who have experienced an oozing poison ivy rash may not want to hear that the plant tends to get larger and produce a more toxic form of its itch-inducing chemical when carbon is high.

The main problem with the good-for-plants argument, however, is that it misses the bigger picture of what carbon does by warming the planet. We told you last week about how warming is contributing to the devastation of pine forests in Canada and the U.S. And the same ground-level ozone that’s bad for human health reduces the yield of important crops like soybeans and cotton.

When I was a kid, my mom used to say something like this: one bunny in a room is cute, but a thousand bunnies in a room would be creepy.

And 9.5 billion tons a year of “bunnies”? Well that just doesn’t sound good at all.

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