Peatlands in Scotland and other cold climes will absorb increasing amounts of carbon dioxide over the coming decades as the planet warms due to climate change, according to new international research.
However, absorption rates will slow after peaking around the end of the century if global temperatures get too hot.
Academics say this “negative feedback” – when climate change causes effects that slow further warming – will increase over the coming decades but will decline after 2100 if warming continues.
Peatlands are a vital sink for carbon, currently storing more than all the world’s vegetation. The latest analysis suggests they will store even more carbon in the future than was previously believed.
In environments such as forests, carbon from dead plants decomposes and is released into the atmosphere. In peatlands, water slows this process and locks in carbon.
Most peatlands are in cold climates in places such as Siberia and Canada, where a rise in temperatures would lengthen the growing season for plants – meaning more plant matter will fall into peat bogs.
But this initial increase in carbon storage, estimated to be about 5 per cent, will be offset by reduced capacity in tropical peat bogs in areas like Borneo and the Amazon.
“Plants living in cold-climate peatlands have it tough for most of the year, but rising global temperatures will give them a longer growing season,” said study leader Dr Angela Gallego-Sala, of the University of Exeter.
“Decomposition in peatlands will speed up as the climate warms, meaning more carbon and methane released, but the overall effect in these high-latitude regions will be increased storage of carbon.
“However, as warming continues, tropical peatlands will store less carbon because decomposition will speed up but higher temperatures in these already warm regions will not boost plant growth.”
Professor Sue Page, of the University of Leicester, says the study highlights the importance of protecting peatlands.
“Restoration efforts such as rewetting drained and degraded peatlands can restore the waterlogged conditions needed to prevent the release of peat carbon. These efforts need to be intensified if we are to avoid accelerating peatland CO2 emissions into the future.”