Land carbon response to positive, zero, and negative CO 2 emissions across Earth system models
Year: 2026
Type: article
Abstract: . Land carbon sinks are responsible for removing about a quarter of anthropogenic CO2 emissions, and make up approximately half of total global carbon sinks. Uncertainty in the response of land carbon sinks to climate and changing atmospheric CO2 are large, and dominate the uncertainty in total carbon sinks under future climate. Understanding the carbon cycle response to net-zero and net-negative emissions has important implications for projecting future climate. Experiments in the "flat10" model intercomparison were designed for directly estimating key climate metrics that underlie carbon budgeting frameworks. Here we characterize the response of land carbon pools and fluxes from ten emissions-driven Earth system models (ESMs) under positive, net-zero, and net-negative CO2 emissions. Although there are many differences in simulated land carbon pools and fluxes across models, we find some consistent behavior across ESMs. 1) During the positive emissions phase, carbon is gained on land primarily in vegetation pools. 2) Following net-negative emissions to the point of cumulative zero emissions, carbon is lost from land in tropical latitudes, primarily from vegetation pools, but in mid- and high-latitudes most models show net land carbon gain, primarily in soil pools. 3) Following an extended period of net-zero emissions, a majority of models again show carbon gain in mid- and high-latitudes and vegetation carbon loss in the tropics. Under net-negative emissions the timing of vegetation carbon response relative to peak emissions is relatively consistent across ESMs, but timing of soil carbon response varies widely, implying larger intermodel disagreement associated with responses of soil carbon which tends to have longer timescales relative to vegetation carbon. Our findings highlight that tropical carbon is most likely to be both gained and subsequently lost under positive, zero, declining, and negative emissions, with possible implications for carbon dioxide removal efforts.
Source: Earth System Dynamics
Authors: Abigail L. S. Swann, Charles D. Koven, Cristian Proistosecu, Rosie A. Fisher, Benjamin M. Sanderson, Victor Brovkin, Tomohiro Hajima, Chris D. Jones, Nancy Y. Kiang, David M. Lawrence, Spencer Liddicoat, Hannah Liddy, Anastasia Romanou, Roland Séférian, Lori T. Sentman, Norman J. Steinert, Jerry Tjiputra, Tilo Ziehn
Institutions: University of Washington, Lawrence Berkeley National Laboratory, University of Illinois Urbana-Champaign, CICERO Center for International Climate Research, Universität Hamburg, Max Planck Institute for Meteorology, Japan Agency for Marine-Earth Science and Technology, Met Office, University of Bristol, Goddard Institute for Space Studies, Columbia University, NSF National Center for Atmospheric Research, Centre National de la Recherche Scientifique, Centre National de Recherches Météorologiques, Météo-France, NOAA Geophysical Fluid Dynamics Laboratory, Bjerknes Centre for Climate Research, NORCE Research AS, Commonwealth Scientific and Industrial Research Organisation, CSIRO Environment
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDGs: Climate action, Life on land
Open Access status: gold
Estimated APC paid: $1,585
Funders: National Science Foundation, National Aeronautics and Space Administration, National Computational Infrastructure, Environmental Restoration and Conservation Agency, Australian Government, Deutsches Klimarechenzentrum, European Commission, Met Office, Ministry of Education, Culture, Sports, Science and Technology, Ministry of Environment, Ministry of the Environment, Government of Japan, Directorate for Geosciences, National Oceanic and Atmospheric Administration, Goddard Space Flight Center, Center for Neuroscience and Regenerative Medicine, National Cancer Institute, HORIZON EUROPE European Research Council
Awards: G1335240794, Quantifying the Drivers of Evapotranspiration Over Land Under Future Climate Conditions, G216056216, The Management and Operation of the National Center for Atmoshperic Research (NCAR), G2865022522, G40072227, G4055512844, G4356674706, G4490316843, G5219813925, Earth system models for the future, G6103217743, G61524141, G7156837616, G7970554450, Optimal High Resolution Earth System Models for Exploring Future Climate Changes, G8681243516, G868160854, G8808512765
OpenAlex ID: W7212030484