Permafrost is ground that remains completely frozen (0°C or less) for at least two years straight. Almost a quarter of the Northern Hemisphere’s landmass has permafrost under its surface, propping up and keeping carbon-dense peatlands cool. Temperature rise is causing the Canadian permafrost to thaw, resulting in visible changes to the landscape and potentially huge methane emissions.
Permafrost is composed of sand, soil and rocks held together by ice, creating formations that can go down to 600 meters deep. Near the surface, permafrost-rich, boreal landscapes contain large quantities of organic carbon from dead plants that couldn’t decompose due to the cold temperatures. When permafrost thaws, the land collapses and transforms into warmer, bacterially active wetlands. The bacteria decompose the organic matter and recycle it into methane, whose emission levels may be higher than expected.
The Boreal Forests are losing area at an estimated 0.26% per year, for a total of around 8% since 1977. A lot of this is converted to wetlands over time, but the exact extent of wetlands is unknown. It is crucial for Canada to make use of the ever more powerful remote sensing technologies available to make an inventory of its wetland surface area.
It is important to note that methane was left out of previous projections by the IPCC as it was poorly understood. It is important to bring attention to this issue to encourage more research to be done.
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- Current wetland emissions are the best current estimates, but these stem from models rather than direct measurements, and are unlikely to be exact.
- The percentage of forest to wetland area conversion comes from extrapolation of observations in several smaller areas. There currently is no full inventory of the Canadian wetlands.
- Estimates of methane release by 2100 were calculated from the data in Zhang et al. 2017.
References for Permafrost Thaw:
Thumbnail image: U.S. Geological Survey
Nisbet, E. G., et al. “Rising atmospheric methane: 2007–2014 growth and isotopic shift.” Global Biogeochemical Cycles 30.9 (2016): 1356-1370.
Treeline data by Brown, J., O. Ferrians, J. A. Heginbottom, and E. Melnikov. 2002.
Circum-Arctic Map of Permafrost and Ground-Ice Conditions, Version 2. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/. 15/05/20.
Baltzer, Jennifer L., et al. “Forests on thawing permafrost: fragmentation, edge effects, and net forest loss.” Global Change Biology 20.3 (2014): 824-834.
Carbon Tracker (https://carbontracker.org/)
The Global Calculator (http://tool.globalcalculator.org/)
Zhang, Zhen, et al. “Emerging role of wetland methane emissions in driving 21st century climate change.” Proceedings of the National Academy of Sciences 114.36 (2017): 9647-9652.