A University of Calgary (U-C) study warns that plants exposed to environmental factors - rising temperature, drought and ultraviolet-B radiation - show enhanced methane emissions.

Methane is a very potent greenhouse gas - 23 times more effective in trapping heat than carbon dioxide.

"Most studies just look at one factor. 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," says David Reid, professor at U-C who co-authored the paper with M. Qaderi.

Reid and Qaderi analysed methane emissions from six crops - faba bean, sunflower, pea, canola, barley and wheat - that were exposed to rising temperature, ultraviolet-B radiation and water stress (drought).

What they found is troubling. These stresses caused plants to emit more methane. In a warmer, drier world methane might be a bigger contributor in global warming than previously thought.

When it comes to the greenhouse effect, methane could be considered the misunderstood and often overlooked orphan greenhouse gas, said an U-C release.

Its concentrations have more than doubled since pre-industrial times. While the growth rate of methane concentrations has slowed since the early 1990s, some scientists say this is only a temporary pause.

These findings were published online in Physiologia Plantarum.