Humble mosses may help greenhouse gas concerns

The thawing of vast stretches of Canadian permafrost — widely seen as a “ticking time bomb” of climate change because of its expected liberation of billions of tonnes of pent-up methane and carbon dioxide — may be much less of a threat than previously believed, according to a new U.S. study of freshly unfrozen peatlands across Western Canada’s northern frontier.

Although the melting of underlying permafrost will release huge amounts of the greenhouse gases blamed for fuelling global warming, researchers who sampled three sites in boreal Alberta, Saskatchewan and Manitoba have discovered that the warmer, softer, wetter soil that results also promotes the growth of new mosses that capture and store about as much carbon from the atmosphere as the thawed ground releases.
“Studies from the 1990s suggested this could be a ticking time bomb,” Michigan State University biologist Merritt Turetsky told CanWest News Service Monday. “Our study does alleviate some of those concerns. It’s not such a dire scenario.”

The sprawling Canadian and Siberian boreal forests — which make up 10% of the Earth’s vegetated surface — are considered crucial to how the planet responds to climate change, an emerging global crisis generally thought to have been triggered by industrial emissions and other human activity but bound up in a complex array of natural cycles and feedback systems involving temperature, precipitation, ocean currents and plant growth.

Peatland ecosystems like the ones studied by the U.S. researchers cover huge swaths of Canada’s boreal and sub-Arctic regions near the southern limits of permafrost. Frozen for hundreds of years, these thawing boreal peatlands — visible as sunken patches of bog in aerial photos used by the researchers to select their test sites — are considered “extremely sensitive” early indicators that climate change is well under way in North America.

“Given that the boreal forest region dominates terrestrial interactions with the Earth’s climate north of 50 degrees north,” the scientists write in the latest edition of the journal Global Change Biology, “and that global warming generally is predicted to be most pronounced in the high latitudes of the northern hemisphere, carbon exchange between boreal peatlands and the atmosphere is particularly relevant to the climate system.”

On this key climate change battleground, the heroes are proving to be humble plants that the researchers describe as “wet-loving sphagnum mosses.” It turns out they thrive in the melted peatlands and “lock in” massive amounts of carbon that would otherwise build up in the atmosphere.

Canada.com