[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/02/EW-02-20-12-Carbon-Dioxide.mp3|titles=EW 02-20-12 Carbon Dioxide]
Plants need carbon dioxide to grow. It’s nature’s plant food. Look around you – every plant that you see is taking carbon dioxide from the atmosphere and using it to make the carbohydrates and cellulose needed for growth. So, beyond all the talk about carbon dioxide leading to global warming, is it possible that more carbon dioxide in the atmosphere might be good for plants?
Scientists have completed a number of studies investigating how plants grow when exposed to high carbon dioxide levels. They’ve found that, when subject to the carbon dioxide levels we expect in 40 years, we can expect 13% more growth from crops and 18% more growth from forests.
This sounds like a boon for farmers and foresters. We might even expect that plants could take a significant amount of carbon dioxide out of the atmosphere, reducing our anxiety about global warming.
But wait: there are some other effects that are less rosy. Working in a forest in North Carolina, several studies have found that poison ivy, a vine in the understory, nearly doubled its growth rate. And, each leaf grown at high carbon dioxide contained more of the nasty oils that make us itch.
High carbon dioxide also resulted in a greater production of pollen by pine trees and a number of weedy species, potentially exacerbating respiratory ailments such as hay fever, asthma, and emphysema.
“Other species of plants that are known allergens, including ragweed, have also increased pollen production under CO2,” says Shannon LaDeau of the Cary Institute. “And in some cases, they found doubling of pollen production at high CO2.”
Like so many changes in the environment, rising carbon dioxide levels in Earth’s atmosphere will have a number of unexpected effects. Some are positive, but many are negative. All are difficult for us to accommodate when the change in the atmosphere comes so rapidly and we have lived under stable conditions for so long.
Web extra
Shannon LaDeau of the Cary Institute says it’s not inherently bad for the forest to have high CO2 levels…
[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/02/LaDeau_extra.mp3|titles=LaDeau_extra]Photo, taken on April 9, 2006 using a Nikon D70s, courtesy of Igor Maminta via Flickr.