Overshoot and (ir)reversibility to 2300 in two CO 2 -emissions driven Earth System models
8 affiliations
- 1Department of Water and Climate, Vrije Universiteit Brussel, Brussels, Belgium
- 2Energy, Climate and Environment Program, International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
- 3School of Earth and Environment, University of Leeds, Leeds, United Kingdom
- 4Max Planck Institute for Meteorology, Hamburg, Germany
- 5Department of Geosciences, University of Oslo, Oslo, Norway
- 6Helmholtz-Zentrum Hereon, Geesthacht, Germany
- 7Norwegian Meteorological Institute, Oslo, Norway
- 8NORCE Climate & Environment and Bjerknes Centre for Climate Research, Bergen, Norway
Abstract
Future climate scenario projections are usually run with prescribed atmospheric CO2 concentrations. However, by not allowing the carbon cycle to interactively respond to emissions in Earth System models, the role of carbon cycle feedbacks on contributions to differences in climate model projections may be undersampled. Here, we present the main findings of two Earth System Models (MPI-ESM1.2-LR and NorESM2-LM) run with CO2 emissions to 2300 for three scenarios, two of which are climate overshoot scenarios, that were part of the Coupled Model Intercomparison Project Phase 6 (CMIP6). These experiments serve three important purposes: (i) an increasing focus on emissions driven runs, supplementing scenarios produced for the Coupled Climate-Carbon Cycle (C4MIP) and Carbon Dioxide Removal (CDRMIP) contributions to CMIP6; (ii) a focus on overshoot scenarios; and (iii) an extension of results beyond 2100, the timescales at which some of the most significant differences play out. Of the two models, NorESM2-LM shows more asymmetry in its response to the same global mean temperature levels before and after peak warming, particularly in terms of its regional pattern of warming and Atlantic Meridional Overturning Circulation (AMOC) response, with a substantially weakened AMOC persisting for decades after peak warming that takes more than a century to recover. In contrast, MPI-ESM1.2-LR shows reversibility with AMOC strength and regional warming more closely following surface temperature, but with some climate signals such as sea-level rise and ocean deoxygenation essentially irreversible. This diversity in model responses highlights the need for further research with a larger model ensemble that focuses on long-term emissions-driven model runs, particularly for overshoot scenarios, for CMIP7.
Related
- Transition to a much warmer climate for the global ocean and Antarctic Ice Sheet coupled system, and its reversibility
- Building materials and emissions from rebuilding under increasing climate-driven flood hazards
- Flooding‐Driven Greenhouse Gas Emissions From Global Upland Croplands
- YAC v3.19.0: scalable online interpolation and flexible coupling for Earth system models
- The calibration deficit: a challenge for Earth system simulation and emulation
BibTeX
@article{smith2026overshoot,
title = {{Overshoot and (ir)reversibility to 2300 in two CO 2 -emissions driven Earth System models}},
author = {Chris Smith and Lennart Ramme and Christopher Wells and Ada Gjermundsen and Hongmei Li and Tatiana Ilyina and Adakudlu Muralidhar and Timothée Bourgeois and Jörg Schwinger and Alejandro Romero-Prieto and Chao Li and Cecilie Mauritzen},
journal = {Earth System Dynamics},
year = {2026},
month = jun,
doi = {10.5194/esd-17-893-2026},
url = {https://doi.org/10.5194/esd-17-893-2026},
note = {CC BY},
}
RIS
TY - JOUR
TI - Overshoot and (ir)reversibility to 2300 in two CO 2 -emissions driven Earth System models
AU - Chris Smith
AU - Lennart Ramme
AU - Christopher Wells
AU - Ada Gjermundsen
AU - Hongmei Li
AU - Tatiana Ilyina
AU - Adakudlu Muralidhar
AU - Timothée Bourgeois
AU - Jörg Schwinger
AU - Alejandro Romero-Prieto
AU - Chao Li
AU - Cecilie Mauritzen
PY - 2026
DA - 2026/06/29
JO - Earth System Dynamics
DO - 10.5194/esd-17-893-2026
UR - https://doi.org/10.5194/esd-17-893-2026
AB - Future climate scenario projections are usually run with prescribed atmospheric CO2 concentrations. However, by not allowing the carbon cycle to interactively respond to emissions in Earth System models, the role of carbon cycle feedbacks on contributions to differences in climate model projections may be undersampled. Here, we present the main findings of two Earth System Models (MPI-ESM1.2-LR and NorESM2-LM) run with CO2 emissions to 2300 for three scenarios, two of which are climate overshoot scenarios, that were part of the Coupled Model Intercomparison Project Phase 6 (CMIP6). These experiments serve three important purposes: (i) an increasing focus on emissions driven runs, supplementing scenarios produced for the Coupled Climate-Carbon Cycle (C4MIP) and Carbon Dioxide Removal (CDRMIP) contributions to CMIP6; (ii) a focus on overshoot scenarios; and (iii) an extension of results beyond 2100, the timescales at which some of the most significant differences play out. Of the two models, NorESM2-LM shows more asymmetry in its response to the same global mean temperature levels before and after peak warming, particularly in terms of its regional pattern of warming and Atlantic Meridional Overturning Circulation (AMOC) response, with a substantially weakened AMOC persisting for decades after peak warming that takes more than a century to recover. In contrast, MPI-ESM1.2-LR shows reversibility with AMOC strength and regional warming more closely following surface temperature, but with some climate signals such as sea-level rise and ocean deoxygenation essentially irreversible. This diversity in model responses highlights the need for further research with a larger model ensemble that focuses on long-term emissions-driven model runs, particularly for overshoot scenarios, for CMIP7.
SN - 2190-4979
SN - 2190-4987
ER -