Antarctic Ice‐Sheet Meltwater Reduces Transient Warming and Climate Sensitivity Through the Sea‐Surface Temperature Pattern Effect

Dong, Yongkwan; Pauling, Andrew G.; Sadai, Shaina; Armour, Kyle C.

doi:10.1029/2022gl101249

Cited by 22 publications

(30 citation statements)

References 66 publications

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“…The ocean physics we discuss in the context of OHUE may additionally modulate future climate through a surface warming “pattern effect” (Armour et al., 2013; Gregory & Andrews, 2016; Stevens et al., 2016; Xie, 2020). Recent work highlights how surface warming patterns are disproportionately influenced by heat uptake and warming in the Southern Ocean (Dong et al., 2022; Lin et al., 2021), a region with a strong influence on climate sensitivity (Andrews et al., 2015; Zelinka et al., 2020). However, the link between OHUE and the pattern effect is thus far unclear.…”

Section: Discussionmentioning

confidence: 99%

Background Pycnocline Depth Constrains Future Ocean Heat Uptake Efficiency

Newsom,

Zanna,

Gregory

2023

Geophysical Research Letters

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The Ocean Heat Uptake Efficiency (OHUE) quantifies the ocean's ability to mitigate surface warming through deep heat sequestration. Despite its importance, the main controls on OHUE, and on its two‐fold spread across contemporary climate models, remain unclear. We argue that OHUE is primarily controlled by mid‐latitude ventilation strength in the background climate, itself related to pycnocline depth and stratification. This hypothesis is supported by a strong correlation between mid‐latitude (30–60°) OHUE and the near‐global average (60°S–60°N) pycnocline depth in CMIP5 and CMIP6 AOGCMs under RCP85/SSP585, and in a parameter perturbation ensemble of ocean GCM (MITgcm) experiments. This correlation explains about 70% of the CMIP5‐6 spread in global OHUE. The relationship provides a pathway toward observationally constraining OHUE, and thus reducing uncertainty in projections of future global climate change and sea level rise.

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Section: Discussionmentioning

confidence: 99%

Background Pycnocline Depth Constrains Future Ocean Heat Uptake Efficiency

Newsom,

Zanna,

Gregory

2023

Geophysical Research Letters

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“…Dong et al (2022a) showed that Southern Ocean cooling can cause a two-way teleconnection that results in a similar SST pattern to observed trends. This implies that other sources of Southern ocean cooling, such as increased surface freshening (Pauling et al, 2016;Haumann et al, 2020;Dong et al, 2022b), might also impact global SST trends. Nonetheless, the anomalous circulation associated with LFC1 indicates a strengthening of the circumpolar westerlies and favors strong surface cooling throughout much of the Southern Ocean.…”

Section: Discussionmentioning

confidence: 99%

Sources of low-frequency variability in observed Antarctic sea ice

Bonan

Dörr

Wills

et al. 2023

Preprint

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Abstract. Antarctic sea ice gradually increased from the late 1970s until 2016, when it experienced an abrupt decline. A number of mechanisms have been proposed for both the gradual increase and abrupt decline of Antarctic sea ice, but how each mechanism manifests spatially and temporally remains poorly understood. Here, we use a statistical method called low-frequency component analysis to analyze the spatial-temporal structure of observed Antarctic sea-ice concentration variability. The identified patterns reveal distinct modes of low-frequency sea ice variability. The leading mode, which accounts for the large-scale, gradual expansion of sea ice, is associated with the Interdecadal Pacific Oscillation and resembles the observed sea-surface temperature trend pattern that climate models have trouble reproducing. The second mode is associated with the central Pacific El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode, and accounts for most of the sea ice variability in the Ross Sea. The third mode is associated with the eastern Pacific ENSO and Amundsen Sea Low, and accounts for most of the pan-Antarctic sea-ice variability and almost all of the sea ice variability in the Weddell Sea. This mode is associated with periods of abrupt Antarctic sea-ice decline and is related to a weakening of the circumpolar westerlies, which favors surface warming through a shoaling of the ocean mixed layer and decreased northward Ekman heat convergence. Broadly, these results suggest that climate model biases in long-term Antarctic sea-ice and global sea-surface temperature trends are related to each other and that eastern Pacific ENSO variability causes abrupt sea ice changes.

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“…There have been a number of idealized Southern Ocean freshwater hosing simulations published (Dong et al., 2022; Hansen et al., 2016; Li, Marshall, et al., 2023; Pauling et al., 2016; Rye et al., 2020) and efforts are underway to build an understanding of the robustness of these results (Swart et al., 2023). However, due to an understandable desire to find a strong signal, the amounts of freshwater added in these simulations have often been much larger than the estimated observed cumulative anomalous mass flux from the 1990s to the present.…”

Section: Introductionmentioning

confidence: 99%

“…feedbacks (Dong et al, 2022;Kim et al, 2022). One specific forcing that was not included in the CMIP5/6 models is the freshwater from historical changes in the mass balance of the Antarctic ice sheet and surrounding ice shelves (Bintanja et al, 2013).…”

mentioning

confidence: 99%

Anomalous Meltwater From Ice Sheets and Ice Shelves Is a Historical Forcing

Schmidt,

Romanou,

Roach

et al. 2023

Geophysical Research Letters

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Recent mass loss from ice sheets and ice shelves is now persistent and prolonged enough that it impacts downstream oceanographic conditions. To demonstrate this, we use an ensemble of coupled GISS‐E2.1‐G simulations forced with historical estimates of anomalous freshwater, in addition to other climate forcings, from 1990 through 2019. There are detectable differences in zonal‐mean sea surface temperatures (SST) and sea ice in the Southern Ocean, and in regional sea level around Antarctica and in the western North Atlantic. These impacts mostly improve the model's representation of historical changes, including reversing the forced trends in Antarctic sea ice. The changes in SST may have implications for estimates of the SST pattern effect on climate sensitivity and for cloud feedbacks. We conclude that the changes are sufficiently large that model groups should strive to include more accurate estimates of these drivers in all‐forcing historical simulations in future coupled model intercomparisons.

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Antarctic Ice‐Sheet Meltwater Reduces Transient Warming and Climate Sensitivity Through the Sea‐Surface Temperature Pattern Effect

Cited by 22 publications

References 66 publications

Background Pycnocline Depth Constrains Future Ocean Heat Uptake Efficiency

Background Pycnocline Depth Constrains Future Ocean Heat Uptake Efficiency

Sources of low-frequency variability in observed Antarctic sea ice

Anomalous Meltwater From Ice Sheets and Ice Shelves Is a Historical Forcing

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