Remote carbon cycle changes are overlooked impacts of land cover and land management changes

Guo, Suqi ; Havermann, Felix ; Hertog, Steven J. De; Luo, Fei ; Manola, Iris; Raddatz, Thomas; Li, Hongmei ; Thiery, Wim ; Lejeune, Quentin ; Schleussner, Carl-Friedrich ; Wårlind, David ; Nieradzik, Lars und Pongratz, Julia (2025): Remote carbon cycle changes are overlooked impacts of land cover and land management changes. In: Earth System Dynamics, Bd. 16, Nr. 2: S. 631-666

Abstract

Land cover and land management changes (LCLMCs) have a substantial impact on the global carbon budget and, consequently, on global climate via the biogeochemical (BGC) effects. The commonly considered BGC effects refer to the direct influence of LCLMCs on local carbon stocks (local BGC effects). However, LCLMCs also influence climate by altering the local surface energy balance due to changes in land surface properties, such as albedo, leaf area, and roughness (local biogeophysical (BGP) effects). Altered local air mass properties can impact regions remote from LCLMCs through advection and changes in large-scale circulation (nonlocal BGP effects). Previous studies have shown potentially substantial nonlocal BGP effects on temperature and precipitation. Given that the terrestrial carbon cycle strongly depends on climate conditions, this raises the question of whether LCLMCs can trigger remote carbon cycle changes (nonlocal BGC effects) – a currently overlooked, potentially large climate and ecosystem impact. To assess the nonlocal BGC effects, we analyze sensitivity simulations for three selected types of hypothetical large-scale LCLMCs, global cropland expansion, global cropland expansion with irrigation, and global afforestation, which were performed by three state-of-the-art Earth system models (ESMs). We separate the nonlocal BGC effect using a checkerboard-like LCLMC perturbation that has previously only been applied to BGP effects. We show that nonlocal BGC effects on vegetation and soil carbon pools persistently accumulate, exceeding natural fluctuations and typically becoming detectable within the first 40 years after LCLMCs. By the end of our 160-year simulation period, nonlocal BGC effects lead to an absolute magnitude of change in total terrestrial carbon stock by 1 to 37 GtC, with strong changes over the densely forested Amazon region (0.2 to 7 GtC) and central Congo Basin region (0.3 to 15 GtC), depending on models and LCLMCs implemented. For the irrigation scenario, the nonlocal BGC effects are comparable to the total BGC effects, with the nonlocal-to-total ratio for vegetation carbon pools commonly reaching around 90 %. Our results reveal that the nonlocal BGC effects could be substantial and call for these effects to be considered for accurate impact assessment and sound policymaking. This becomes even more relevant when LCLMCs are expected to play a pivotal role in achieving the Paris Agreement's goal of limiting global warming below 1.5 °C above pre-industrial levels.

• Dokumententyp: Zeitschriftenartikel
• EU Funded Grant Agreement Number: 776608
• EU-Projekte: Horizon 2020
• Fakultät: Geowissenschaften > Department für Geographie > Physische Geographie und Landnutzungssysteme
• Themengebiete: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
• ISSN: 2190-4987
• Sprache: Englisch
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892