LONG-TERM STUDY CONTRADICTS BELIEF THAT RISING CO2 COULD BENEFIT PLANTS
After more than 40 years of research on grassland productivity, Montana State University scientists have found that, contrary to long-held theories, an increase in carbon dioxide will not help plant growth.
The researchers found that while today’s carbon dioxide levels are 20 percent greater than those in 1969, the grass production in a Montana meadow is now half of what it was over 40 years ago.
The researchers predicted that earlier studies failed to consider other kinds of contributing factors such as extreme weather, water levels and animals. From 1969 to 2012, the university team measured plant productivity at a U.S. Forest Service meadow just outside Bozeman, Montana. When it became evident that carbon dioxide wasn’t contributing to plant growth and that the growth was actually declining, they looked for other causes. Ultimately, the team determined, the decline in grass production could be attributed to increasing aridity and declining late-summer rainfall.
“Dryness over the last several decades is outpacing any potential growth stimulation from increasing atmospheric carbon dioxide,” said Jack Brookshire, a professor at Montana State University, to the journal Nature Communications.
Importantly, these results demonstrate that the key to understanding the current climate-ecosystem relationship is understanding and observing past climate-ecosystem relationships.
— Emma Murray