Smith et al. (2026) Overshoot and (ir)reversibility to 2300 in two CO 2 -emissions driven Earth System models

Identification

• Journal: Earth System Dynamics
• Year: 2026
• Date: 2026-06-29
• Authors: Chris Smith, Lennart Ramme, Christopher Wells, Ada Gjermundsen, Hongmei Li, Tatiana Ilyina, Adakudlu Muralidhar, Timothée Bourgeois, Jörg Schwinger, Alejandro Romero-Prieto, Chao Li, Cecilie Mauritzen
• DOI: 10.5194/esd-17-893-2026

Research Groups

• Department of Water and Climate, Vrije Universiteit Brussel, Brussels, Belgium
• Energy, Climate and Environment Program, International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
• School of Earth and Environment, University of Leeds, Leeds, UK
• Max Planck Institute for Meteorology, Hamburg, Germany
• Department of Geosciences, University of Oslo, Oslo, Norway
• Helmholtz-Zentrum Hereon, Geesthacht, Germany
• Norwegian Meteorological Institute, Oslo, Norway
• NORCE Climate & Environment and Bjerknes Centre for Climate Research, Bergen, Norway

Short Summary

This study investigates the overshoot and irreversibility of climate change in two CO2-emissions driven Earth System models (ESMs) to 2300. The results show that NorESM2-LM exhibits more asymmetry in its climate response at the same global mean temperature levels before and after peak warming, particularly in terms of regional pattern of warming and Atlantic Meridional Overturning Circulation (AMOC) response.

Objective

• Investigate the overshoot and irreversibility of climate change in CO2-emissions driven ESMs to 2300.
• Analyze the long-term impacts and reversibility of climate overshoot under negative emissions scenarios.

Study Configuration

• Spatial Scale: Global scale, with a focus on regional patterns of warming and AMOC response.
• Temporal Scale: From 2015 to 2300, with a focus on the long-term impacts and reversibility of climate overshoot.

Methodology and Data

• Models used: MPI-ESM1.2-LR and NorESM2-LM, two ESMs that are well-performing in reproducing observed atmospheric CO2 concentrations.
• Data sources: CO2 emission pathways from the SSP scenarios, extended after 2100 as described in Meinshausen et al. (2020).

Main Results

• NorESM2-LM shows more asymmetry in its climate response at the same global mean temperature levels before and after peak warming.
• The AMOC index is reduced during the warm phase in both models, but with a much larger reduction in NorESM2-LM.
• In the overshoot scenarios, the land and ocean both transition from a net sink to a net source of carbon around 2100.

Contributions

• This study provides new insights into the long-term impacts and reversibility of climate overshoot under negative emissions scenarios.
• The results highlight the importance of considering the role of the carbon cycle in ESMs, particularly in the context of overshoot scenarios.

Funding

• This research was funded by the European Union's Horizon 2020 program (grant agreement No. 776186) and the Norwegian Research Council (project number 262938).

Citation

@article{Smith2026Overshoot,
  author = {Smith, Chris and Ramme, Lennart and Wells, Christopher and Gjermundsen, Ada and Li, Hongmei and Ilyina, Tatiana and Muralidhar, Adakudlu and Bourgeois, Timothée and Schwinger, Jörg and Romero-Prieto, Alejandro and Li, Chao and Mauritzen, Cecilie},
  title = {Overshoot and (ir)reversibility to 2300 in two CO 2 -emissions driven Earth System models},
  journal = {Earth System Dynamics},
  year = {2026},
  doi = {10.5194/esd-17-893-2026},
  url = {https://doi.org/10.5194/esd-17-893-2026}
}