Antarctic Ocean and Sea Ice Response to Ozone Depletion: A Two-Time-Scale Problem

Ferreira, David; Marshall, John; Bitz, Cecilia M.; Solomon, Susan; Plumb, R. Alan

doi:10.1175/jcli-d-14-00313.1

Cited by 228 publications

(337 citation statements)

References 64 publications

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“…The results from this study broadly agree with ozone depletion experiments, meant to simulate the increase in zonal wind stress in the Southern Hemisphere during austral summer (Ferreira et al 2015;Solomon et al 2015). The average SST difference during the last 10 yr of our WP experiment resemble the slow time-scale response in Ferreira et al (2015), in which there is warming around Antarctica and cooling at midlatitudes (Fig.…”

Section: Discussionsupporting

confidence: 83%

Southern Ocean Overturning Compensation in an Eddy-Resolving Climate Simulation

Bishop

Gent

Bryan

et al. 2016

Journal of Physical Oceanography

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The Southern Ocean's Antarctic Circumpolar Current (ACC) and meridional overturning circulation (MOC) response to increasing zonal wind stress is, for the first time, analyzed in a high-resolution (0.18 ocean and 0.258 atmosphere), fully coupled global climate simulation using the Community Earth System Model. Results from a 20-yr wind perturbation experiment, where the Southern Hemisphere zonal wind stress is increased by 50% south of 308S, show only marginal changes in the mean ACC transport through Drake Passage-an increase of 6% [136-144 Sverdrups (Sv; 1 Sv [ 10 6 m 3 s 21 )] in the perturbation experiment compared with the control. However, the upper and lower circulation cells of the MOC do change. The lower cell is more affected than the upper cell with a maximum increase of 64% versus 39%, respectively. Changes in the MOC are directly linked to changes in water mass transformation from shifting surface isopycnals and sea ice melt, giving rise to changes in surface buoyancy forcing. The increase in transport of the lower cell leads to upwelling of warm and salty Circumpolar Deep Water and subsequent melting of sea ice surrounding Antarctica. The MOC is commonly supposed to be the sum of two opposing components: a wind-and transient-eddy overturning cell. Here, the transient-eddy overturning is virtually unchanged and consistent with a large-scale cancellation of localized regions of both enhancement and suppression of eddy kinetic energy along the mean path of the ACC. However, decomposing the time-mean overturning into a time-and zonal-mean component and a standing-eddy component reveals partial compensation between wind-driven and standing-eddy components of the circulation.

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Section: Discussionsupporting

confidence: 83%

Southern Ocean Overturning Compensation in an Eddy-Resolving Climate Simulation

Bishop

Gent

Bryan

et al. 2016

Journal of Physical Oceanography

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“…As a result, sea ice extent around the West Antarctic Peninsula (WAP) has declined by up to 40% over the past 26 years (Smith and Stammerjohn, 2001;Ducklow et al, 2007;Parkinson and Cavalieri, 2012). Modeling studies predict that continued global warming will eventually override the SAM and ENSO effects, increasing warming to the atmosphere and ocean, and resulting in significant declines in SIE around Antarctica (Bracegirdle et al, 2008;Ferreira et al, 2015).…”

Section: Seasonal Sea Ice Zonementioning

confidence: 99%

Southern Ocean Phytoplankton in a Changing Climate

2017

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Phytoplankton are the base of the Antarctic food web, sustain the wealth and diversity of life for which Antarctica is renowned, and play a critical role in biogeochemical cycles that mediate global climate. Over the vast expanse of the Southern Ocean (SO), the climate is variously predicted to experience increased warming, strengthening wind, acidification, shallowing mixed layer depths, increased light (and UV), changes in upwelling and nutrient replenishment, declining sea ice, reduced salinity, and the southward migration of ocean fronts. These changes are expected to alter the structure and function of phytoplankton communities in the SO. The diverse environments contained within the vast expanse of the SO will be impacted differently by climate change; causing the identity and the magnitude of environmental factors driving biotic change to vary within and among bioregions. Predicting the net effect of multiple climate-induced stressors over a range of environments is complex. Yet understanding the response of SO phytoplankton to climate change is vital if we are to predict the future state/s of the ecosystem, estimate the impacts on fisheries and endangered species, and accurately predict the effects of physical and biotic change in the SO on global climate. This review looks at the major environmental factors that define the structure and function of phytoplankton communities in the SO, examines the forecast changes in the SO environment, predicts the likely effect of these changes on phytoplankton, and considers the ramifications for trophodynamics and feedbacks to global climate change. Predictions strongly suggest that all regions of the SO will experience changes in phytoplankton productivity and community composition with climate change. The nature, and even the sign, of these changes varies within and among regions and will depend upon the magnitude and sequence in which these environmental changes are imposed. It is likely that predicted changes to phytoplankton communities will affect SO biogeochemistry, carbon export, and nutrition for higher trophic levels.

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“…Further north, much of the ice pack lies over the region of upwelling Circumpolar Deep Water. This means that near surface waters are constantly replenished by Circumpolar Deep Water (which due to its long residence time in the deep ocean has a limited anthropogenic signal), thus delaying any anthropogenic warming at the surface [Ferreira et al, 2015;Marshall et al, 2015;Armour et al, 2016].…”

Section: 1002/2016jc012111mentioning

confidence: 99%

Century‐scale perspectives on observed and simulated Southern Ocean sea ice trends from proxy reconstructions

et al. 2016

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Since 1979 when continuous satellite observations began, Southern Ocean sea ice cover has increased, whilst global coupled climate models simulate a decrease over the same period. It is uncertain whether the observed trends are anthropogenically forced or due to internal variability, or whether the apparent discrepancy between models and observations can be explained by internal variability. The shortness of the satellite record is one source of this uncertainty, and a possible solution is to use proxy reconstructions, which extend the analysis period but at the expense of higher observational uncertainty. In this work, we evaluate the utility for change detection of 20th century Southern Ocean sea ice proxies. We find that there are reliable proxies for the East Antarctic, Amundsen, Bellingshausen and Weddell sectors in late winter, and for the Weddell Sea in late autumn. Models and reconstructions agree that sea ice extent in the East Antarctic, Amundsen and Bellingshausen Seas has decreased since the early 1970s, consistent with an anthropogenic response. However, the decrease is small compared to internal variability, and the change is not robustly detectable. We also find that optimal fingerprinting filters out much of the uncertainty in proxy reconstructions. The Ross Sea is a confounding factor, with a significant increase in sea ice since 1979 that is not captured by climate models; however, existing proxy reconstructions of this region are not yet sufficiently reliable for formal change detection.

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Antarctic Ocean and Sea Ice Response to Ozone Depletion: A Two-Time-Scale Problem

Cited by 228 publications

References 64 publications

Southern Ocean Overturning Compensation in an Eddy-Resolving Climate Simulation

Southern Ocean Overturning Compensation in an Eddy-Resolving Climate Simulation

Southern Ocean Phytoplankton in a Changing Climate

Century‐scale perspectives on observed and simulated Southern Ocean sea ice trends from proxy reconstructions

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