Emulating absent land processes reduces carbon budgets in CMIP6 models
Abstract
The Transient Climate Response to cumulative Emissions (TCRE) is the cornerstone of estimates of carbon emissions budgets to future warming targets, characterising the near-linear relationship between the increase in global mean temperature and cumulative emissions of CO ₂ . TCRE is derived from highly sophisticated Earth System Models (ESMs) - some, however, lack important processes known to have a large impact on TCRE. Here, we use multiple configurations of UKESM, a full-complexity ESM, to estimate how TCRE of 11 ESMs that participated in Coupled Model Intercomparison Project 6 would change if each included six terrestrial carbon cycle related processes present in UKESM, such as nitrogen limitation of photosynthesis and fire-vegetation interactions. We find that accounting for processes not included in the models increases their TCRE by an average of 21.4% implying a reduction of 16.0% ± 0.8% in the carbon budget for the transition from 1.5 °C to 2 °C.
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BibTeX
@article{liddicoat2026emulating,
title = {{Emulating absent land processes reduces carbon budgets in CMIP6 models}},
author = {Spencer K. Liddicoat and Chris D. Jones and Lina M. Mercado and Eddy Robertson and Stephen Sitch and Andy Wiltshire},
journal = {Communications Earth \& Environment},
year = {2026},
month = oct,
doi = {10.1038/s43247-026-04111-9},
url = {https://www.nature.com/articles/s43247-026-04111-9},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Emulating absent land processes reduces carbon budgets in CMIP6 models
AU - Spencer K. Liddicoat
AU - Chris D. Jones
AU - Lina M. Mercado
AU - Eddy Robertson
AU - Stephen Sitch
AU - Andy Wiltshire
PY - 2026
DA - 2026/10/24
JO - Communications Earth & Environment
DO - 10.1038/s43247-026-04111-9
UR - https://www.nature.com/articles/s43247-026-04111-9
AB - The Transient Climate Response to cumulative Emissions (TCRE) is the cornerstone of estimates of carbon emissions budgets to future warming targets, characterising the near-linear relationship between the increase in global mean temperature and cumulative emissions of CO ₂ . TCRE is derived from highly sophisticated Earth System Models (ESMs) - some, however, lack important processes known to have a large impact on TCRE. Here, we use multiple configurations of UKESM, a full-complexity ESM, to estimate how TCRE of 11 ESMs that participated in Coupled Model Intercomparison Project 6 would change if each included six terrestrial carbon cycle related processes present in UKESM, such as nitrogen limitation of photosynthesis and fire-vegetation interactions. We find that accounting for processes not included in the models increases their TCRE by an average of 21.4% implying a reduction of 16.0% ± 0.8% in the carbon budget for the transition from 1.5 °C to 2 °C.
SN - 2662-4435
ER -