Climate change may boost crops’ methane output

Crop stresses typically linked to climate change, such as increased temperatures, drought and UV-B radiation, might actually hasten climate change by causing crops to emit more methane into the atmosphere.

In a study released Monday, biological scientists David Reid and Mirwais Qaderi of the University of Calgary found some plants show “enhanced” methane emissions under increased levels of such stresses.

“Most studies just look at one factor,” Reid said in a U of C release. “We wanted to mix a few of the environmental factors that are part of the climate change scenario to study a more true-to-life impact climate change has on plants.”

Reid and Qaderi analyzed the methane emissions from six Canadian crops — fababean, sunflower, pea, canola, barley and wheat — after exposure to combinations of “three components of global climate change,” meaning temperature, ultraviolet-B radiation and water stress.

These stresses caused plants to emit more methane, said the researchers, who used a gas chromatograph in controlled-environment growth chambers to measure the plants’ output.

The methane output varied by crop species, they noted, finding the emissions highest for peas and lowest for barley.


Qaderi and Reid described their findings as “troubling” because they suggest that “in a warmer, drier world methane might be a bigger contributor in global warming than previously thought.”

As a greenhouse gas, methane is considered 23 times more effective than carbon dioxide in terms of trapping heat in Earth’s atmosphere, the U of C said.

While much of the focus in climate change research is on carbon dioxide, methane’s concentrations in the atmosphere have “more than doubled since pre-industrial times,” the U of C said.

The growth rate of methane concentrations has slowed since the early 1990s, but the university cited other scientists as saying that may be only a “temporary pause.”

The study’s results may point to “the possibility of yet another possible feedback phenomena which could add to global warming,” Qaderi said in the university’s release.

However, Qaderi and Reid said, since elevated levels of carbon dioxide have been observed to “counteract” the negative effects of some environmental stresses, the two are now studying the effect of increased carbon dioxide with factors such as drought, higher temperature and UV-B on methane production in crops.

Reid is a professor in the U of C’s department of biological sciences, while Qaderi is a research associate. Their paper was published last month in the online edition of the plant science journal Physiologia Plantarum.

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