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​The CLIMB Research Group explores how terrestrial ecosystems, primarily forests, are impacted by global change and how these responses influence climate change and other planetary boundaries. We apply the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC), which is the land surface component of the Canadian Earth System Model (CanESM), in collaboration with the Canadian Centre for Climate Modelling and Analysis (Environment and Climate Change Canada). Our work also extends across international networks of terrestrial biosphere models (TBMs) and Earth System Models (ESMs) used to project climate change, assess climate change impacts, and inform climate change policy by the Intergovernmental Panel on Climate Change (IPCC).

Research areas

  • Nutrient limitation of the terrestrial carbon sink​: ​The terrestrial biosphere – plants and soils – currently sequesters one-quarter of anthropogenic CO2 emissions, making it pivotal to regulating atmospheric CO2 and climate. A major uncertainty in projecting climate change is resolving the extent to which nutrients will constrain plant growth and carbon sequestration under global change, thereby constraining the remaining carbon emission budget. We analyze, evaluate, and improve the representation of nutrient limitation within TBMs and ESMs.
  • Planetary boundaries - modification of biogeochemical flows: Nutrient losses from the terrestrial biosphere lead to negative consequences such as nitrogen runoff and aquatic eutrophication, soil emissions of N2O (a potent greenhouse gas), and emissions of reactive nitrogen gases from wildfires, all of which impact climate change and other planetary boundaries such as stratospheric ozone depletion, atmospheric aerosol loading, and biosphere integrity. We analyze, evaluate, and improve the representation of nutrient losses within TBMs and ESMs.
  • Impacts of human activities on the terrestrial biosphere: We explore how human activities – CO2 emissions, land use change, fertilizer application, population growth, etc. – cumulatively have impacted and will impact future terrestrial ecosystems and climate change using models and their cross-cutting impacts on natural and human systems.
    • Wildfires and climate change: We examine how wildfires are intensifying due to climate change and their impacts using models, with a focus on Canadian landscapes.
    • Agricultural intensification: We examine how agricultural expansion is driving N2O emissions both directly and indirectly through increasing nitrogen deposition, which also influences carbon sequestration in natural ecosystems.​
    • etc.
  • More stuff (see Publications below)!

Publications

  1. Gong, C., Y. Wang, H. Tian, S. Kou-Giesbrecht, N. Vuichard, and S. Zaehle. Uncertainties in fertilizer-induced emissions of soil nitrogen oxide and the associated impacts on ground-level ozone and methane. 2025. Atmospheric Chemistry and Physics.
  2. Kou-Giesbrecht, S., C. R. Reis Ely, S. S. Perakis, C. C. Cleveland, D. N. L. Menge, S. C. Reed, B. N. Taylor, S. A. Batterman, T. E. Crews, K. A. Dynarski, M. Gei, M. J. Gundale, D. F. Herridge, S. E. Jovan, M. B. Peoples, J. Piipponen, E. Rodríguez-Caballero, V. G. Salmon, F. M. Soper, A. P. Staccone, B. Weber, C. A. Williams, and N. Wurzburger. 2025. Overestimated natural biological nitrogen fixation translates to an exaggerated CO2 fertilization effect in Earth System Models. Proceedings of the National Academy of Sciences.
    1. Media coverage: Scientific Models Overestimate Natural Processes That Mitigate Climate Change
    2. Media coverage: Earth’s future carbon sink is weaker than climate models assume
  3. Zantout, K., J. Balkovic, M. Billing, C. Folberth, S. N. Gosling, T. Hank, S. Hantson, T. Iizumi, A. Ito, J. Jägermeyr, A. K. Jain, N. Khabarov, S. Kou-Giesbrecht, F. Li, M. Li, T.-S. Lin, W. Liu, C. Müller, M. Okada, S. Ostberg, K. Otta, S. Rabin, C. P. O. Reyer, C. Scheer, J. M. Schneider, F. Zabel, K. Frieler, and J. Schewe. 2025. Shifting dominant periods in extreme climate impacts under global warming. Nature Communications.
  4. Kou-Giesbrecht, S. 2025. Nitrogen Cycling in Earth System Models: From Constraining Carbon Budgets to Projecting Pollution for Planetary Stewardship. JGR Biogeosciences (Invited Article).
    1. ​Media coverage: Global Climate Models Need the Nitrogen Cycle – All of It, Eos
  5. Cooley, S. S., E. Moore, J. M. Martinez, J. Fahlen, E. Maybach, M. Gollerkeri, A. Rao Vasa, S. Kou-Giesbrecht, A. Huddell, L. Norton, K. Cawse-Nicholson, R. S. DeFries, M. Uriarte, and D. L. Menge. 2025. Global 'climate opportunity benefit' of forest regeneration: meta-analysis shows warming from soil CH4 and N2O is small relative to agriculture. Global Biogeochemical Cycles.
  6. Reis Ely, C., S. Perakis, C. Cleveland, D. Menge, S. Reed, B. Taylor, S. Batterman, C. Clark, T. Crews, K. Dynarski, M. Gei, M. Gundale, D. Herridge, S. Jovan, S. Kou-Giesbrecht, M. Peoples, J. Piipponen, E. Rodriguez-Caballero, V. Salmon, F. Soper, A. Staccone, B. Weber, C. Williams, and N. Wurzburger. 2025. Global terrestrial nitrogen fixation and its modification by agriculture. Nature.
  7. Luo, M., X. Zhao, D. Hao, B. Bond-Lamberty, A. Daigneault, P. Patel, S. Kou-Giesbrecht, C. Reyer, H. Dashti, and M. Chen. 2025. Role of forest carbon change in shaping future land use and land cover change. Global Change Biology. Global Change Biology.
  8. Kou-Giesbrecht, S., V. Arora, C. Jones, V. Brovkin, T. Hajima, M. Kawamiya, S. Liddicoat, A. Winkler, and S. Zaehle. 2025. Rising nitrogen deposition leads to only a minor increase in CO2 uptake in Earth system models. Nature Communications Earth & Environment.
  9. Park, C., K. Takahashi, S. Fujimori, T. Jansakoo, C. Burton, H. Huang, S. Kou-Giesbrecht, C. Reyer, M. Mengel, E. Burke, F. Li, S. Hantson, J. Takakura, D. Kun Lee, and T. Hasegawa. 2024. Attributing human mortality from fire PM2.5 to climate change. Nature Climate Change.
  10. Burton, C., S. Lampe, D. Kelley, W. Thiery, S. Hantson, N. Christidis, L. Gudmundsson, M. Forrest, E. Burke, J. Chang, H. Huang, A. Ito, S. Kou-Giesbrecht, G. Lasslop, W. Li, L. Nieradzik, F. Li, Y. Chen, J. Randerson, C. Reyer, and M. Mengel. 2024. Global burned area increasingly explained by climate change. Nature Climate Change.
    1. Media coverage: Thousands of annual deaths are linked to wildfire smoke inhalation: new research, The Canadian Press
    2. Media coverage: CBC Radio One Halifax
  11. Li, L., C. Lu, W. Winiwater, H. Tian, J. Canadell, A. Ito, A. Jain, S. Kou-Giesbrecht, S. Pan, N. Pan, H. Shi, Q. Sun, N. Vuichard, S. Ye, S. Zaehle, and Q. Zhu. 2024. Enhanced nitrous oxide emission factors due to climate change increase the mitigation challenge in the agricultural sector. Global Change Biology.
  12. Gong, C., H. Tian, H. Liao, N. Pan, S. Pan, A. Ito, A. Jain, S. Kou-Giesbrecht, F. Joos, Q. Sun, H. Shi, N. Vuichard, Q. Zhu, C. Peng, F. Maggi, F. Tang, and S. Zaehle. 2024. Global net climate effects of anthropogenic reactive nitrogen. Nature. 
  13. Kou-Giesbrecht, S., V. K. Arora, C. Seiler, and L. Wang. 2024. The impacts of modelling prescribed vs. dynamic land cover on greening of the Arctic and Amazonian dieback in a high CO2 future scenario. Biogeosciences.
  14. Sun, Q., F. Joos, S. Lienert, S. Berthet, D. Carroll, C. Gong, A. Ito, A. Jain, S. Kou-Giesbrecht, A. Landolfi, M. Manizza, N. Pan, M. Prather, P. Regnier, L. Resplandy, R. Séférian, H. Shi, P. Suntharalingam, R. Thompson, H. Tian, N. Vuichard, S. Zaehle, and Q. Zhu. 2024. The modeled seasonal cycles of surface N2O fluxes and atmospheric N2O. Global Biogeochemical Cycles.
  15. Tian, H., N. Pan, R. Thompson, J. Canadell, P. Suntharalingam, P. Regnier, …, S. Kou-Giesbrecht, … and Q. Zhu. 2024. Global Nitrous Oxide Budget 1980-2020. Earth System Science Data.​
  16. Heinicke, S., J. Volkholz, J. Schewe, S. Gosling, H. Schmied, S. Zimmermann,M. Mengel, I. Sauer, P. Burek, J. Chang, S. Kou-Giesbrecht, M. Grillakis, L. Guillaumot, N. Hanasaki, A. Koutroulis, K. Otta, W. Qi, Y. Satoh, T. Stacke, T. Yokohata, and K. Frieler. 2024. Global hydrological models overestimate river discharge. Environmental Research Letters.
  17. Gong, C., S. Kou-Giesbrecht, and S. Zaehle. 2024. Anthropogenic-driven perturbations on nitrogen cycles and interactions with climate changes. Current Opinion in Green and Sustainable Chemistry.
  18. Seiler, C., S. Kou-Giesbrecht, V. K. Arora, and J. Melton. 2024. The impact of climate forcing biases and the nitrogen cycle on land carbon balance projections. Journal of Advances in Modeling Earth Systems.
  19. Menge, D. N. L., S. Kou-Giesbrecht, B. N. Taylor, P. R. Akana, A. Butler, K. A. Carreras Pereira, S. S. Cooley, V. M. Lau, and E. L. Lauterbach. 2023. Terrestrial Phosphorus Cycling: Responses to Climatic Change. Annual Review of Ecology, Evolution, and Systematics.
  20. Carreras Pereira, K. A., A. A. Wolf, S. Kou-Giesbrecht, P. R. Akana, J. L. Funk, and D. N. L. Menge. 2023. Allometric relationships for eight species of 4–5 year old nitrogen-fixing and non-fixing trees. PLOS ONE.
  21. Kou-Giesbrecht, S., V. K. Arora, C. Seiler, A. Arneth, S. Falk, A. K. Jain, F. Joos, D. Kennedy, J. Knauer, S. Sitch, M. O’Sullivan, N. Pan, Q. Sun, H. Tian, N. Vuichard, and S. Zaehle. 2023. Evaluating nitrogen cycling in terrestrial biosphere models: a disconnect between the carbon and nitrogen cycles. Earth System Dynamics.
  22. Kou-Giesbrecht, S., and V. K. Arora. 2023. Compensatory Effects Between CO2, Nitrogen Deposition, and Nitrogen Fertilization in Terrestrial Biosphere Models Without Nitrogen Compromise Projections of the Future Terrestrial Carbon Sink. Geophysical Research Letters.
  23. Arora, V. K., C. Seiler, L. Wang, and S. Kou-Giesbrecht. 2023. Towards an ensemble-based evaluation of land surface models in light of uncertain forcings and observations. Biogeosciences.
  24. Menge, D. N. L., A. A. Wolf, J. L. Funk, S. S. Perakis, P. R. Akana, R. Arkebauer, T. A. Bytnerowicz, K. A. Carreras Pereira, A. M. Huddell, S. Kou-Giesbrecht, and S. K. Ortiz. 2023. Tree symbioses sustain nitrogen fixation despite excess nitrogen supply. Ecological Monographs.
  25. Kou-Giesbrecht, S., and V. K. Arora. 2022. Representing the Dynamic Response of Vegetation to Nitrogen Limitation via Biological Nitrogen Fixation in the CLASSIC Land Model. Global Biogeochemical Cycles.
  26. Kou-Giesbrecht, S., S. Malyshev, I. M. Cano, S. W. Pacala, E. Shevliakova, T. A. Bytnerowicz, and D. N. L. Menge. 2021. A novel representation of biological nitrogen fixation and competitive dynamics between nitrogen-fixing and non-fixing plants in a land model (GFDL LM4.1-BNF). Biogeosciences.
  27. Kou-Giesbrecht, S., and D. N. L. Menge. 2021. Nitrogen-fixing trees increase soil nitrous oxide emissions: a meta-analysis. Ecology.
  28. Kou-Giesbrecht, S., J. L. Funk, S. S. Perakis, A. A. Wolf, and D. N. L. Menge. 2021. N supply mediates the radiative balance of N2O emissions and CO2 sequestration driven by N-fixing vs. non-fixing trees. Ecology.
  29. Staccone, A. P., S. Kou-Giesbrecht, B. N. Taylor, and D. N. L. Menge. 2021. Nitrogen-fixing trees have no net effect on forest growth in the coterminous United States. Journal of Ecology.
  30. Kou-Giesbrecht, S., and D. N. L. Menge. 2019. Nitrogen-fixing trees could exacerbate climate change under elevated nitrogen deposition. Nature Communications.

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