The ocean’s role in the transient response of climate to abrupt greenhouse gas forcing

By John Marshall, Jeffery R. Scott, K. Armour, Jean-Michel Campin, M. Kelley, A. Romanou. Climate Dynamics, 2015

226 citations recorded by the source corpus.

We study the role of the ocean in setting the patterns and timescale of the transient response of the climate to anthropogenic greenhouse gas forcing. A novel framework is set out which involves integration of an ocean-only model in which the anthropogenic temperature signal is forced from the surface by anomalous downwelling heat fluxes and damped at a rate controlled by a ‘climate feedback’ parameter. We observe a broad correspondence between the evolution of the anthropogenic temperature ($$T_{anthro}$$Tanthro) in our simplified ocean-only model and that of coupled climate models perturbed by a quadrupling of $$\hbox {CO}_{2}$$CO2. This suggests that many of the mechanisms at work in fully coupled models are captured by our idealized ocean-only system. The framework allows us to probe the role of the ocean in delaying warming signals in the Southern Ocean and in the northern North Atlantic, and in amplifying the warming signal in the Arctic. By comparing active and passive temperature-like tracers we assess the degree to which changes in ocean circulation play a role in setting the distribution and evolution of $$T_{anthro}$$Tanthro. The background ocean circulation strongly influences the large-scale patterns of ocean heat uptake and storage, such that $$T_{anthro}$$Tanthro is governed by an advection/diffusion equation and weakly damped to the atmosphere at a rate set by climate feedbacks. Where warming is sufficiently small, for example in the Southern Ocean, changes in ocean circulation play a secondary role. In other regions, most noticeably in the North Atlantic, changes in ocean circulation induced by $$T_{anthro}$$Tanthro are central in shaping the response.

Subfields: Global and Planetary Change, Oceanography

View Paper: https://www.semanticscholar.org/paper/eabb296336488a8e8ba944732b15ad1fc6f34822

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Citations in the corpus

Observations, inferences, and mechanisms of the Atlantic Meridional Overturning Circulation: A review (2016, background): “…of its relative warmth, the NH emits slightly more outgoing longwave radiation than the SH, leading to the slight asymmetry in top-of-the-atmosphere radiation and supporting the small northward heat transport by the coupled system across the equator [Kang et al., 2014; Marshall et al., 2014a].”
Arctic amplification of climate change: a review of underlying mechanisms (2021, background): “…delivered to the mixed layer through ocean transport changes goes into warming the mixed layer, most of this additional energy goes into melting sea ice and warming the near-surface atmosphere (Bitz et al 2006, Koenigk and Brodeau 2014, Marshall et al 2015, Docquier et al 2019, Alkama et al 2020a).”
Towards multi-resolution global climate modeling with ECHAM6–FESOM. Part I: model formulation and mean climate (2015, result): “The stronger long-time scale adjustment to greenhouse gas forcing in the Southern Ocean compared to the Arctic Ocean has been found in earlier modeling studies (Goosse and Renssen 2001; Marshall et al. 2013).”
Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach (2017, background): “…Andrews, 2016; Zhou et al., 2016], the latter being affected by decadal climate variability [Watanabe et al., 2014; Meehl et al., 2016], non-CO2 forcings [Takahashi and Watanabe, 2016; Smith et al., 2016] and ocean heat uptake [Marshall et al., 2015; Winton et al., 2013; Rugenstein et al., 2016].”