A more thorough way to estimate how much the world's boreal-Arctic wetlands and lakes contribute to current and future harmful methane emissions has been developed in part by University of Alberta researchers.
The research, reported in Nature Climate Change, uses a novel approach to estimate future methane emissions, by taking into account both the direct effects of warming, such as longer summers and increased microbial activity, and effects of permafrost thaw, which is creating new, often high-emission wetlands and lakes following landscape collapse. The study is also one of the first to consider emissions from both wetlands and lakes in a unified framework, which avoids errors that occur when they are modelled separately.
The comprehensive new method represents a vital step forward in the ability to model and better understand how such emissions could increase in a warming climate, says scientist McKenzie Kuhn, who led the study to earn a PhD in Land and Water Resource Management from the Faculty of Agricultural, Life & Environmental Sciences (ALES).
"It's an important tool that will help us more accurately determine emissions reductions goals; while there is no way to stop natural methane emissions, understanding their magnitude and response helps better inform how much we should reduce human sources of methane emissions to curb climate warming."
To create their improved modelling approach, Kuhn, co-author David Olefeldt, a professor in ALES, and an international research team compiled data from 189 prior studies, representing decades of field research, on methane emissions from wetlands and lakes. The studies dated back to the 1970s, representing a total of 1,800 sites from around the world. The massive amount of information on methane emissions was then merged with the Boreal–Arctic Wetland and Lake Dataset, a map developed a few years ago by Kuhn, Olefeldt and other researchers to model such emissions.
The new method distinguishes several wetland and lake classes and accounts for their different methane emissions, addressing a "key shortcoming" of past approaches, where the assumption was that all wetlands have the same emissions, says Olefeldt.
"Merging the two datasets was crucial, as different types of wetlands and lakes have very distinct methane emissions."
For example, drier types of wetlands can have very low methane emissions, while others with thawed soils have much higher emissions. Similarly, some lake types, such as those on the Canadian shield, generally have very low emissions, while smaller ponds in peatland or tundra areas with rapid thaw have much higher emissions.
"Our study shows that a better representation of distinct wetland and lake classes greatly improves our ability to model boreal-Arctic methane emissions."
