It’s pretty obvious when cows emit methane gas.
Plants are a little more subtle about it.
Yet plant growth may produce as much as 10 to 30 percent of the planet’s annual methane output, according to a study recently published in Nature.
Now a University of Calgary researcher has found that plants under environmental stress release even more methane than normal. The findings could have implications in 20 to 30 years when it’s expected the Earth’s climate will be drier and hotter, particularly in Western Canada.
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Botany and biology professor David Reid looked at what impact multiple stresses have on a plant’s methane production, including heat, drought and ultraviolet radiation.
He exposed six crops – wheat, barley, canola, sunflower, fababean and peas – to various combinations of the three components, and concluded that methane production increased by about 25 percent under stress.
“We’re not really sure why,” Reid said. “The exact biochemical source of methane in a plant is a bit of a mystery, and so is the reason for the increase.”
The results suggest that in a warmer, drier world of the future, plant-produced methane could be a bigger contributor to climate change and global warming than previously thought.
While carbon dioxide receives most of the attention in public discussions about climate change, methane is a highly potent greenhouse gas, 23 times more effective than CO2 in trapping heat. Luckily, said Reid, there is a lot less methane than CO2 in the atmosphere.
Concentrations of methane in the atmosphere have more than doubled since pre-industrial times, and while the growth rate has slowed in the past 20 years, many scientists believe that is only temporary.
Until recently, scientists believed that plant-related methane formed only in oxygen-free environments, such as bogs and rice paddies.
But a team of European researchers identified a large range of plants that release methane under normal growing conditions. The gas also seeps from dead plant material.
Reid said he’s not suggesting plant production is bad for the environment, noting that plants absorb huge amounts of CO2 out of the atmosphere.
“I guess this is just another annoying factor to add to the pot,” he said.
He next plans to add increased levels of CO2 to the mix of stresses to which the plants are subjected and assess the impact on methane production.
