Ice Core Evidence for Antarctic Sea Ice Decline Since the 1950s

Curran, Mark A. J.; Ommen, T. D. van; Morgan, Vin; Phillips, Katrina L.; Palmer, Anne S.

doi:10.1126/science.1087888

Cited by 306 publications

(365 citation statements)

References 25 publications

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“…In particular, the models and reconstructions both show decreases in the East Antarctic and Amundsen-Bellingshausen sectors at approximately the same time, providing possible evidence of a very modest anthropogenic signal, whilst the comparison of the reconstructions with the CMIP5 control runs helps place previously reported ice core proxy trends [Curran et al, 2003;Abram et al, 2010;Sinclair et al, 2014] in the context of Antarctic SIE's large internal variability. This analysis is especially useful for the East Antarctic sector, since the relatively short passive microwave record shows an increase in ASO ice cover since 1979, in contrast to coupled climate models.…”

Section: 1002/2016jc012111mentioning

confidence: 88%

“…The Law Dome and AP regions of influence are slightly different from those used in Curran et al [2003] and Abram et al [2010], respectively, probably because the JIC data were used for calibration in the original studies. Interestingly, the SOFI records show correlations not just with the Weddell Sea, but also inverse correlations with the Amundsen and Bellingshausen Seas [Murphy et al, 2014].…”

Section: Reconstruction Calibration and Validationmentioning

confidence: 99%

“…The East Antarctic reconstruction is derived from the Law Dome methanesulphonic acid (MSA) record [Curran et al, 2003], with published data from 1841 to 1995. MSA is a by-product of biological activity in the seasonal sea ice zone, i.e., the area that is ice-free in summer and ice-covered in winter [Curran and Jones, 2000].…”

Section: Proxy Datamentioning

confidence: 99%

“…Summer ice edge has been estimated using historical whaling records [de la Mare, 1997Mare, , 2009], but there are concerns over the reliability of this approach [Ackley et al, 2003], and they do not provide a continuous record to the present day. Several geophysical regional reconstructions have been published in recent years [Curran et al, 2003;Abram et al, 2010;Murphy et al, 2014;Sinclair et al, 2014;Thomas and Abram, 2016], all of which report statistically significant local changes in sea ice cover, but these reconstructions have not previously been compared with simulated variability or forced response.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: 1002/2016jc012111mentioning

confidence: 88%

Section: Reconstruction Calibration and Validationmentioning

confidence: 99%

Section: Proxy Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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“…Examples include strong associations between icecore Na + concentrations and the ASL pressure system (Kreutz et al, 2000;Kaspari et al, 2004), icecore methanesulphonic acid concentrations and sea ice extent (Welch et al, 1993;Meyerson et al, 2002;Curran et al, 2003;Abram et al, 2007), ice-core stable isotopes and temperature (Schneider et al, 2004(Schneider et al, , 2006, and icecore non-sea-salt-Ca 2+ (nssCa) concentrations used as a NAMI proxy in this study. A previous ice-core nssCa study (Yan et al, 2005) established that a statistically significant positive relationship exists between the strength of SH westerlies and nssCa concentrations in two West Antarctic ice cores (SDM-94 and 00-1) from 1948 to 2002.…”

Section: Methods and Resultsmentioning

confidence: 99%

An ice‐core proxy for northerly air mass incursions into West Antarctica

Dixon

Mayewski

Goodwin

et al. 2011

Intl Journal of Climatology

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ABSTRACT:A 200-year proxy for northerly air mass incursions (NAMI) into central and western West Antarctica is developed from the examination of 19 shallow (21-150 m deep) Antarctic ice-core non-sea-salt (nss) Ca 2+ concentration records. The NAMI proxy reveals a significant rise in recent decades. This rise is unprecedented for at least the past 200 years and is coincident with anthropogenically driven changes in other large-scale Southern Hemisphere (SH) environmental phenomena such as greenhouse gas (GHG) induced warming, ozone depletion, and the associated intensification of the SH westerlies. The Hysplit trajectory model is used to examine air mass transport pathways into West Antarctica. Empirical orthogonal function analysis, in combination with trajectory results, suggests that atmospheric circulation is the dominant factor affecting nssCa 2+ concentrations throughout central and western West Antarctica. Ozone recovery will likely weaken the spring-summer SH westerlies in the future. Consequently, Antarctica could lose one of its best defences against SH GHG warming.

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Variability of sea‐ice in the northern Weddell Sea during the 20th century

et al. 2014

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The record of winter fast-ice in the South Orkney Islands, northern Weddell Sea, Antarctica, is over a century long and provides the longest observational record of sea-ice variability in the Southern Hemisphere. Here we present analyses of the series of fast-ice formation and breakout dates from 1903 to 2008. We show that over the satellite era (post-1979), the timing of both final autumn formation and complete spring breakout of fast-ice is representative of the regional sea-ice concentrations (SIC) in the northern Weddell Sea, and associated with atmospheric conditions in the Amundsen Sea region to the west of the Antarctic Peninsula. Variation in the fast-ice breakout date is influenced by the intensity of the westerly/ north-westerly winds associated with the Southern Annular Mode (SAM). In contrast, the date of ice formation displays correlations with regional oceanic and sea-ice conditions over the previous 18 months, which indicate a preconditioning during the previous summer and winter, and exhibits variability associated with variation in tropical Pacific sea-surface temperature (i.e., the El Niño-Southern Oscillation, ENSO). A reduction in fast-ice duration at the South Orkney Islands around the 1950s was associated with both later formation and earlier breakout. However, there were marked changes in variability (with periodicities of 3-5, 7-9, and 20 years) in each of the series and in their relationships with ENSO and SAM, indicating the need for caution in interpreting changes in ice conditions based on shorter-term satellite series.

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Ice Core Evidence for Antarctic Sea Ice Decline Since the 1950s

Cited by 306 publications

References 25 publications

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

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

An ice‐core proxy for northerly air mass incursions into West Antarctica

Variability of sea‐ice in the northern Weddell Sea during the 20th century

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