In this section
@article{Williams:2025:10.5194/bg-22-7167-2025,
author = {Williams, RG and Goodwin, P and Ceppi, P and Jones, CD and MacDougall, AH},
doi = {10.5194/bg-22-7167-2025},
journal = {Biogeosciences},
pages = {7167--7186},
title = {A normalised framework for the Zero Emissions Commitment},
url = {http://dx.doi.org/10.5194/bg-22-7167-2025},
volume = {22},
year = {2025}
}
TY - JOUR
AB - The Zero Emissions Commitment (ZEC) measures the transient climate response after carbon emissions cease, defined by whether there is a continued rise or decrease in global surface temperature. This delayed climate response affects the maximum cumulative carbon emission to avoid exceeding a warming target. In a set of 9 Earth system models following an idealised atmospheric CO<inf>2</inf> scenario with a cumulative emission of 1000 Pg C, the ZEC after 50 years ranges from −0.3 to 0.28 °C with a model mean of −0.11 °C and standard deviation of 0.19 °C. In order to understand these different climate responses, a normalised framework is introduced that quantifies the relative importance of carbon, radiative and thermal drivers of the ZEC. Inter-model differences in the ZEC are primarily due to differences in the radiative response, planetary heat uptake and the land carbon sink, with more minor contributions from differences in the ocean carbon sink and climate feedback. The ZEC response is controlled by opposing-signed contributions: (i) cooling from a decrease in radiative forcing from a carbon contribution due to increasing land and ocean carbon uptake, versus (ii) surface warming from a thermal contribution involving a decline in the fraction of radiative forcing used for planetary heat uptake plus possible amplification by climate feedback. The carbon contribution to the ZEC depends on the increase in the ocean carbon sink and whether the land carbon sink either increases or saturates in time. The thermal contribution to the ZEC depends upon how radiative forcing is partitioned between planetary heat uptake and radiative response with the radiative response either declining in time or remaining constant. These inferences as to the controls of the ZEC broadly carry over for diagnostics for a large ensemble, observationally-constrained, efficient Earth system model using two different emission scenarios to reach net zero. The larg
AU - Williams,RG
AU - Goodwin,P
AU - Ceppi,P
AU - Jones,CD
AU - MacDougall,AH
DO - 10.5194/bg-22-7167-2025
EP - 7186
PY - 2025///
SN - 1726-4170
SP - 7167
TI - A normalised framework for the Zero Emissions Commitment
T2 - Biogeosciences
UR - http://dx.doi.org/10.5194/bg-22-7167-2025
VL - 22
ER -