Large uncertainty in carbon uptake potential of land‐based climate‐change mitigation efforts |
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| Authors: | Andreas Krause Thomas A M Pugh Anita D Bayer Wei Li Felix Leung Alberte Bondeau Jonathan C Doelman Florian Humpenöder Peter Anthoni Benjamin L Bodirsky Philippe Ciais Christoph Müller Guillermo Murray‐Tortarolo Stefan Olin Alexander Popp Stephen Sitch Elke Stehfest Almut Arneth |
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| Affiliation: | 1. Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research – Atmospheric Environmental Research (IMK‐IFU), Garmisch‐Partenkirchen, Germany;2. School of Geography, Earth & Environmental Sciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham, UK;3. Laboratoire des Sciences du Climat et l'Environnement, CEA‐CNRS‐UVSQ, Gif‐sur‐Yvette, France;4. College of Life and Environmental Sciences, University of Exeter, Exeter, UK;5. Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (Mediterranean Institute for Biodiversity and Ecology IMBE), Aix‐en‐Provence, France;6. Department of Climate, Air and Energy, Netherlands Environmental Assessment Agency (PBL), The Netherlands;7. Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany;8. Catedra CONACyT comisionado al Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico;9. Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden |
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| Abstract: | Most climate mitigation scenarios involve negative emissions, especially those that aim to limit global temperature increase to 2°C or less. However, the carbon uptake potential in land‐based climate change mitigation efforts is highly uncertain. Here, we address this uncertainty by using two land‐based mitigation scenarios from two land‐use models (IMAGE and MAgPIE) as input to four dynamic global vegetation models (DGVMs; LPJ‐GUESS, ORCHIDEE, JULES, LPJmL). Each of the four combinations of land‐use models and mitigation scenarios aimed for a cumulative carbon uptake of ~130 GtC by the end of the century, achieved either via the cultivation of bioenergy crops combined with carbon capture and storage (BECCS) or avoided deforestation and afforestation (ADAFF). Results suggest large uncertainty in simulated future land demand and carbon uptake rates, depending on the assumptions related to land use and land management in the models. Total cumulative carbon uptake in the DGVMs is highly variable across mitigation scenarios, ranging between 19 and 130 GtC by year 2099. Only one out of the 16 combinations of mitigation scenarios and DGVMs achieves an equivalent or higher carbon uptake than achieved in the land‐use models. The large differences in carbon uptake between the DGVMs and their discrepancy against the carbon uptake in IMAGE and MAgPIE are mainly due to different model assumptions regarding bioenergy crop yields and due to the simulation of soil carbon response to land‐use change. Differences between land‐use models and DGVMs regarding forest biomass and the rate of forest regrowth also have an impact, albeit smaller, on the results. Given the low confidence in simulated carbon uptake for a given land‐based mitigation scenario, and that negative emissions simulated by the DGVMs are typically lower than assumed in scenarios consistent with the 2°C target, relying on negative emissions to mitigate climate change is a highly uncertain strategy. |
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| Keywords: | avoided deforestation and afforestation BECCS carbon dioxide removal land‐based mitigation negative emissions |
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