Global — Peat, the accumulated turf made up of decayed vegetation, forms in many parts of the world in places like bogs, moors, and swamp forests. Due to its high carbon content, it can be harvested and burned as fuel. There are estimates that the global inventory of peat, covering 2 percent of all land area, contains 8 billion terajoules of energy. A new study has revealed that peat also has a high potential to contribute to climate change. The study, published by researchers from Bangor University in Maine, found that drought causes the release of far more carbon dioxide from peat than previously assumed.
Peatlands of the world lie in regions which are predicted to experience more frequent and severe droughts as climate change deepens. This will lead to the peat drying out and releasing vast quantities of CO2 into the atmosphere. Peat normally contains ample moisture which locks in the greenhouse gas. As it dries, the peat becomes exposed to the air where CO2 can be released.
The new study was published in the journal Nature Geosciences by Dr. Nathalie Fenner and Professor Chris Freeman of Bangor University. They found that not only with drought increase the rate of CO2 release, but that the release will also continue after the drought has concluded and the peat is re-wetted. This is because the new rainwater will drain away the dried out peatlands as dissolved organic carbon, where it can also be released.
“As our global climate and rainfall patterns change, our peatlands may not have sufficient opportunity to recover between these drought-induced episodes of CO2 loss,” explains Dr Fenner. “What we previously perceived as a ‘spike’ in the rate of carbon loss during drying out, now appears far more prolonged- with a potential peak after the initial drought period is over.”
Other potential problems from future droughts in peatland may be the deterioration of drinking water quality from the dissolved organic carbon. Peatlands can often be found upland in the northern hemisphere and their waters may travel down gradient to reservoirs or into the groundwater. Also, the loss of carbon may lead to degradation of the peatland itself. More lowland flooding may be possible as the peatland’s natural sponge-like quality diminishes. Habitat and species loss may also occur.
“The previous focus of research in this area has been on the drought period, and our own work identified how the release of CO2 occurs,” explains Prof Freeman, who leads the Wolfson Peatland Carbon Capture Laboratory at Bangor University. “We were initially surprised at finding that the effects are so prolonged- we think what’s happening is microbial and that this activity has been triggered by the introduction of oxygen into previously waterlogged conditions. Once the water returns, conditions have changed and the microbes are further able to thrive until conditions eventually return to normal.”