Controls of the Transient Climate Response to Emissions: effects of physical feedbacks, heat uptake and saturation of radiative forcing

Williams, Ric, Ceppi, Paulo and Katavouta, Anna ORCID: 0000-0002-1587-4996 (2020) Controls of the Transient Climate Response to Emissions: effects of physical feedbacks, heat uptake and saturation of radiative forcing. In: EGU General Assembly 2020, 2020-5-4 - 2020-5-8, Online.

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Abstract

The surface warming response to carbon emissions, defines a climate metric, the Transient Climate Response to cumulative carbon Emissions (TCRE), which is important in estimating how much carbon may be emitted to avoid dangerous climate. The TCRE is diagnosed from a suite of 9 CMIP6 Earth system models following an annual 1% rise in atmospheric CO2 over 140 years. The TCRE is nearly constant in time during emissions for these climate models, but its value differs between individual models. The near constancy of this climate metric is due to a strengthening in the surface warming per unit radiative forcing, involving a weakening in both the climate feedback parameter and fraction of radiative forcing warming the ocean interior, which are compensated by a weakening in the radiative forcing per unit carbon emission from the radiative forcing saturating with increasing atmospheric CO2. Inter-model differences in the TCRE are mainly controlled by the surface warming response to radiative forcing with large inter-model differences in physical climate feedbacks dominating over smaller, partly compensating differences in ocean heat uptake. Inter-model differences in the radiative forcing per unit carbon emission provide smaller inter-model differences in the TCRE, which are mainly due to differences in the ratio of the radiative forcing and change in atmospheric CO2 rather than from differences in the airborne fraction. Hence, providing tighter constraints in the climate projections for the TCRE during emissions requires improving estimates of the physical climate feedbacks, the rate of ocean heat uptake, and how the radiative forcing saturates with atmospheric CO2.

Item Type:	Conference or Workshop Item (Unspecified)
Uncontrolled Keywords:	13 Climate Action
Depositing User:	Symplectic Admin
Date Deposited:	03 Nov 2020 10:29
Last Modified:	20 Apr 2024 04:28
DOI:	10.5194/egusphere-egu2020-8433
Open Access URL:	http://doi.org/10.5194/egusphere-egu2020-8433
Related URLs:	Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3105605