Climate change is expected to increase the frequency and severity of drought in many of the world’s peatlands which, in turn, is liable to release far more carbon dioxide than had previously been assumed.
This new discovery comes as a result of a report published in the journal Nature Geosciences by Dr Nathalie Fenner and Professor Chris Freeman of Bangor University, Wales.
The report shows that the subsequent effects from a period of severe drought on peatland will last long past the drought itself.
“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 the paper’s lead author, Dr Nathalie 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.”
Drought Rain Drought
Droughts impact peatland by drying out the normally soaking wet earth, releasing into the atmosphere massive stores of carbon dioxide that have been building up for 360 million years. Peat is essentially wet earth containing the normal decomposition of plant materials, which create the very distinct feel and smell of peatland.
According to the International Mire Conservation Group, Earth’s peatlands contain some 550 gigatonnes of carbon.
Fenner and Freeman now believe that drought increases the rate of release of carbon dioxide for up to a decade.
Previously, scientists had assumed that most of the carbon dioxide was released immediately. However, the new research shows that the carbon dioxide release continues and may even increase when – after the drought – rains return and dissolve the organic carbon.
On top of the increase in carbon dioxide release there are other consequences that the scientists brought to light.
Many regions that lie below a peatland have their water pass through that same peatland. Increases in the dissolved carbon dioxide in the water draining out of a peatland could adversely affect the quality of the drinking water downstream.
On top of this, the loss of carbon could ultimately end up seeing the peatland disappear entirely. Upload regions of the northern hemisphere could see peatland contributing to increased lowland flooding if the peatland can no longer take in as much water as it used to be able to.
Unsurprisingly, the flora and fauna of peatlands will also suffer.
“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 Chris 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.”