Mismatch of N release from the permafrost and vegetative uptake opens pathways of increasing nitrous oxide emissions in the high Arctic

Lacroix, Fabrice; Zaehle, Sönke; Caldararu, Silvia; Schaller, Jörg; Stimmler, Peter; Holl, David; Kutzbach, Lars; Göckede, Mathias (2022). Mismatch of N release from the permafrost and vegetative uptake opens pathways of increasing nitrous oxide emissions in the high Arctic. Global change biology, 28(20), pp. 5973-5990. Wiley 10.1111/gcb.16345

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iogeochemical cycling in permafrost-affected ecosystems remains associated with large uncertainties, which could impact the Earth's greenhouse gas budget and future climate policies. In particular, increased nutrient availability following permafrost thaw could perturb the greenhouse gas exchange in these systems, an effect largely unexplored until now. Here, we enhance the terrestrial ecosystem model QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system), which simulates fully coupled carbon (C), nitrogen (N) and phosphorus (P) cycles in vegetation and soil, with processes relevant in high latitudes (e.g., soil freezing and snow dynamics). In combination with site-level and satellite-based observations, we use the model to investigate impacts of increased nutrient availability from permafrost thawing in comparison to other climate-induced effects and CO2 fertilization over 1960 to 2018 across the high Arctic. Our simulations show that enhanced availability of nutrients following permafrost thaw account for less than 15% of the total Gross primary productivity increase over the time period, despite simulated N limitation over the high Arctic scale. As an explanation for this weak fertilization effect, observational and model data indicate a mismatch between the timing of peak vegetative growth (week 26–27 of the year, corresponding to the beginning of July) and peak thaw depth (week 32–35, mid-to-late August), resulting in incomplete plant use of nutrients near the permafrost table. The resulting increasing N availability approaching the permafrost table enhances N loss pathways, which leads to rising nitrous oxide (N2O) emissions in our model. Site-level emission trends of 2 mg N m−2 year−1 on average over the historical time period could therefore predict an emerging increasing source of N2O emissions following future permafrost thaw in the high Arctic.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Physics Institute

UniBE Contributor:

Lacroix, Fabrice Kenneth Michel

Subjects:

500 Science > 530 Physics
500 Science > 550 Earth sciences & geology

ISSN:

1354-1013

Publisher:

Wiley

Language:

English

Submitter:

Fabrice Kenneth Michel Lacroix

Date Deposited:

30 Jan 2024 07:30

Last Modified:

30 Jan 2024 07:30

Publisher DOI:

10.1111/gcb.16345

PubMed ID:

35852443

BORIS DOI:

10.48350/192228

URI:

https://boris.unibe.ch/id/eprint/192228

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