What is Earth's equilibrium climate sensitivity? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
What is Earth's equilibrium climate sensitivity?
Plain · changed
Revision 1: Doubling CO2 will warm Earth by somewhere around 2.5 to 4 degrees once the oceans catch up. Narrowing that range has proved hard for decades.
Revision 2: Doubling $\mathrm{CO_2}$ will warm Earth by somewhere around 2.5 to 4 degrees once the oceans catch up. Narrowing that range has proved hard for decades.
Precise · changed · core
Revision 1: Equilibrium climate sensitivity (ECS) is the equilibrium global-mean surface air temperature change for doubled CO2 (forcing about $4\mathrm{e}3\,\mathrm{erg}/(\mathrm{s}\,\mathrm{cm}^{2})$). The 2020 multi-evidence assessment gives a 66 percent range of about $2.6\ \text{to}\ 3.9\,\mathrm{K}$ and the 2021 IPCC assessment a likely range of $2.5\ \text{to}\ 4\,\mathrm{K}$. An answer is a 66 percent range narrower than $1\,\mathrm{K}$ consistent with process, historical and paleoclimate evidence.
Revision 2: Equilibrium climate sensitivity (ECS) is the equilibrium global-mean surface air temperature change for doubled $\mathrm{CO_2}$ (forcing about $4\mathrm{e}3\,\mathrm{erg}/(\mathrm{s}\,\mathrm{cm}^{2})$). The 2020 multi-evidence assessment gives a 66 percent range of about $2.6\ \text{to}\ 3.9\,\mathrm{K}$ and the 2021 IPCC assessment a likely range of $2.5\ \text{to}\ 4\,\mathrm{K}$. An answer is a 66 percent range narrower than $1\,\mathrm{K}$ consistent with process, historical and paleoclimate evidence.
Settled by
Process-level constraints on cloud feedbacks combined with paleoclimate and historical energy-budget estimates that agree within a sub-kelvin range.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
partially-resolved
Status note
(empty)
Posed since
1896

Decisions