Kou-Giesbrecht Sian, Arora Vivek K, Jones Chris D, Brovkin Victor, Hajima Tomohiro, Kawamiya Michio, Liddicoat Spencer K, Winkler Alexander J, Zaehle Sönke
Department of Earth and Environmental Sciences, Dalhousie University, Halifax, Canada.
Canadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada, Victoria, Canada.
Commun Earth Environ. 2025;6(1):216. doi: 10.1038/s43247-024-01943-1. Epub 2025 Mar 19.
Current frameworks for evaluating biogeochemical climate change feedbacks in Earth System Models lack an explicit consideration of nitrogen cycling in the land and ocean spheres despite its vital role in limiting primary productivity. As coupled carbon-nitrogen cycling becomes the norm, a better understanding of the role of nitrogen cycling is needed. Here we develop a new framework for quantifying carbon-nitrogen feedbacks in Earth System Models and show that rising nitrogen deposition acts as a negative feedback over both land and ocean, enhancing carbon dioxide (CO) fertilisation in a model ensemble. However, increased CO uptake due to rising nitrogen deposition is small relative to the large reduction in CO uptake when coupled carbon-nitrogen cycling is implemented in Earth System Models. Altogether, rising nitrogen deposition leads to only a minor increase in CO uptake but also enhances nitrous oxide (NO) emissions over land and ocean, contributing only marginally to mitigating climate change.
尽管氮循环在限制初级生产力方面起着至关重要的作用，但目前用于评估地球系统模型中生物地球化学气候变化反馈的框架缺乏对陆地和海洋领域氮循环的明确考虑。随着碳氮耦合循环成为常态，需要更好地理解氮循环的作用。在这里，我们开发了一个新的框架来量化地球系统模型中的碳氮反馈，并表明氮沉降增加在陆地和海洋上都起到负反馈作用，在一个模型集合中增强了二氧化碳（CO）施肥效应。然而，相对于在地球系统模型中实施碳氮耦合循环时CO吸收的大幅减少，氮沉降增加导致的CO吸收增加量较小。总体而言，氮沉降增加仅导致CO吸收量略有增加，但也增加了陆地和海洋上的一氧化二氮（NO）排放，对缓解气候变化的贡献微乎其微。
