The Active Role of the Ocean in the Temporal Evolution of Climate Sensitivity. Issue 1 (8th January 2018)

• Record Type: Journal Article
• Authors: Garuba, Oluwayemi A.; Lu, Jian; Liu, Fukai; Singh, Hansi A.
• Is Part Of: Geophysical research letters. Volume 45:Issue 1(2018)
• Page Start: 306
• Page End: 315
• Publication Date: 2018-01-08
• Subjects: Climate sensitivity -- Ocean heat uptake -- Ocean circulation change -- Radiative Feedbacks -- Air‐sea interactions; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL075633
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The temporal evolution of the effective climate sensitivity is shown to be influenced by the changing pattern of sea surface temperature (SST) and ocean heat uptake (OHU), which in turn have been attributed to ocean circulation changes. A set of novel experiments are performed to isolate the active role of the ocean by comparing a fully coupled CO2 quadrupling community Earth System Model (CESM) simulation against a partially coupled one, where the effect of the ocean circulation change and its impact on surface fluxes are disabled. The active OHU is responsible for the reduced effective climate sensitivity and weaker surface warming response in the fully coupled simulation. The passive OHU excites qualitatively similar feedbacks to CO2 quadrupling in a slab ocean model configuration due to the similar SST spatial pattern response in both experiments. Additionally, the nonunitary forcing efficacy of the active OHU (1.7) explains the very different net feedback parameters in the fully and partially coupled responses. Key Points: Pure atmosphere‐driven "passive" and ocean‐driven "active" climate responses are isolated using a novel partial coupling method The spatial pattern evolution of surface temperatures and ocean heat uptake is attributable to the active ocean‐driven component The active ocean response is largely responsible for reduced effective sensitivity compared to that at equilibrium