EGU24-5924, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

How will climate warming impact winter CO2 emissions from northern peatlands?

Fereidoun Rezanezhad1, Arash Rafat2,3, Eunji Byun4, Stephanie Slowinski1, Katie Hettinga1, Saraswati Saraswati1,5, Bhaleka Persaud1, William L. Quinton2,3, Elyn. R. Humphreys6, Kara Webster7, Haojie Liu8, Bernd Lennartz8, Maria Strack9, and Philippe Van Cappellen1
Fereidoun Rezanezhad et al.
  • 1Ecohydrology Research Group, Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Canada
  • 2Department of Geography & Environmental Studies, Wilfrid Laurier University, Waterloo, ON, Canada
  • 3Cold Regions Research Centre, Wilfrid Laurier University, Waterloo, ON, Canada;
  • 4Department of Earth System Sciences, Yonsei University, Seoul, South Korea
  • 5Department of Geography and Geospatial Sciences, South Dakota State University, Brookings, SD 57007, USA
  • 6Department of Geography and Environmental Studies, Carleton University, Ottawa, ON, Canada
  • 7Canadian Forest Service - Natural Resources Canada, Sault Ste Marie, ON, Canada
  • 8Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, Germany
  • 9Department of Geography and Environmental Management, University of Waterloo, Waterloo, Canada

Canada’s peatlands hold more than half of the organic carbon stocks stored in all Canadian soils. Over 90% of these peatlands are in the boreal and subarctic regions that are undergoing accelerated climate warming. Climate models project that the rate of warming will continue through the 21st century, with the greatest warming occurring during the non-growing season (NGS). Given that NGS carbon dioxide (CO2) emissions are mainly driven by microbial respiration, warming, even at sub-zero temperatures, is expected to increase the CO2 emissions during the NGS. Therefore, understanding the factors that regulate CO2 emissions during the NGS is critical for predicting the fate of the climate-sensitive peat organic carbon stocks. In this presentation, we examine the role of environmental variables in NGS CO2 emissions at a Canadian peatland research site to infer how these emissions may evolve under climate warming scenarios. We developed a support-vector regression machine-learning model whose results imply that soil moisture, soil temperature, snow cover, and photosynthesis are key predictor variables explaining the variability of net ecosystem CO2 fluxes during the NGS. The model was applied to a 13-year (1998-2010) continuous record of eddy covariance flux measurements at the Mer Bleue Bog (located near Ottawa, Canada). The CO2 fluxes were most sensitive to the net radiation above the canopy, wind speed, soil temperature, and soil moisture. Next, we used regional climate projections for the site to forecast future changes in the net ecosystem exchange of CO2 during the NGS. Under the highest radiative forcing scenario, the NGS Mer Bleue peatland CO2 emission rates could experience a 103% increase by 2100. Time permitting, we will also discuss results from a laboratory incubation CO2 experiment with soils from Canadian boreal and temperate peatlands under variable moisture and temperature conditions. The incubation temperature ranged from −10 to +35°C and included freeze–thaw events. The results showed that CO2 production rates increased more sharply with temperature for the boreal peatland soils than the temperate ones. This indicates that boreal peatlands may increase future NGS CO2 losses to a larger degree than temperate peatlands. Our results thus further highlight the potential for a strong positive climate feedback loop from accelerated peatland CO2 emissions. They also point to the need for more realistic representations of northern soil processes in earth system models.

How to cite: Rezanezhad, F., Rafat, A., Byun, E., Slowinski, S., Hettinga, K., Saraswati, S., Persaud, B., Quinton, W. L., Humphreys, E. R., Webster, K., Liu, H., Lennartz, B., Strack, M., and Van Cappellen, P.: How will climate warming impact winter CO2 emissions from northern peatlands?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5924,, 2024.