Peatland, or partially decomposed organic matter, comprises 3% of the world’s land surface area, but holds about twice the total amount of carbon stored in biomass on Earth. This explains why there has been so much attention on the protection of the world’s peatland such as those in the Arctic permafrost zone as well as in tropical areas such as Indonesia, where in the latter, slash and burn agricultural practices create annual fire hazards that resulted in the evolution of significant quantities of the greenhouse gas, carbon dioxide, into the atmosphere.
Being acidic, peatland is a mix of organic carbon that could not be degraded by microorganisms into either methane or carbon dioxide depending on the level of oxygen available. Thus, it is in essence a store of localized carbon in the soil, which in the context of climate change, is useful for reducing the rise of carbon dioxide concentration in the atmosphere.
Nevertheless, with global warming and need for production of more food and agricultural crops for cash, many of the world’s peatland are increasingly vulnerable to dramatic changes: warming induced enhanced biodegradation in the permafrost regions, as well as fire induced release of carbon dioxide in regions with slash and burn agriculture.
Stored carbon in peatland is primarily released through two metabolic routes by biodegradation activities of microorganisms: anaerobic digestion, and biomineralization. Specifically, in deeper layers of the soil or where the soil is waterlogged (and thus lacked oxygen), anaerobic digestion of the stored carbon results in the emission of methane, a greenhouse gas with greater greenhouse warming potential than carbon dioxide, but which can be degraded by ultraviolet light. On the other hand, in soils which are better aerated with higher oxygen content, biomineralization occurs where organic carbon is completely degraded into carbon dioxide and water. Hence, depending on the level of oxygen available in soil, one of the above two routes predominate in contributing to the release of stored carbon from peatland through natural biotic processes.
What human induced climate change does to the equilibrium is the acceleration of biotic release of carbon in peatland through enhanced microbial degradation activities in a warmer environment. Thus, this accelerated release of carbon dioxide or methane into the atmosphere serves as a positive feedback loop feeding into the temperature trajectory set by existing carbon dioxide concentration in the atmosphere. Which explains why protecting the world’s peatland from further degradation is so important in humanity’s goal to avoid dangerous anthropogenic interference (DAI) in Earth’s climate system, defined as the rise of the Earth’s average surface temperature beyond 2 oC above preindustrial levels.
Thus, slowing the rise of atmospheric carbon dioxide and, by extension, temperature, is key to reducing the release of stored carbon in peatland that will accelerate climate change. Another important factor that would retard the release of carbon from tropical peatland exposed to seasonal slash and burn practices, would be better regulatory oversight on the use of fire for land clearing in peatland. Additionally, creation of protected zones of peatland and prevention of their draining for agricultural uses would be another useful policy tool for reducing carbon emissions from peatland. All in all, peatland may hold an important lever to whether our civilization experiences accelerated climate change due to unabated carbon dioxide emissions from our fossil fuel powered societies.
Category: climate change,
Tags: methane, carbon dioxide, climate change, global warming, anaerobic degradation, biotic processes, peatland,