Increased influence of ENSO on Antarctic temperature since the Industrial Era

Rahaman, Waliur; Chatterjee, Sourav; Ejaz, Tariq; Thamban, Meloth

doi:10.1038/s41598-019-42499-x

Cited by 25 publications

(30 citation statements)

References 56 publications

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“…Therefore, it is important to identify the climate modes that influenced SH precipitation and RH. Recent study of Rahaman et al (2019) based on multiple δ 18 O ice core records from West and East Antarctica shows that both the regions come under the influence of ENSO and PDO. Further, they have suggested that influence of ENSO on East Antarctic temperature has increased since the beginning of the industrial Era (~1850).…”

Section: Resultsmentioning

confidence: 99%

Enhanced Dust Influx to South Atlantic Sector of Antarctica During the Late‐20th Century: Causes and Contribution to Radiative Forcing

et al. 2020

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Atmospheric dust influences global climate and ocean biogeochemistry. Here we present a high-resolution ice core dust record (1905 from coastal Dronning Maud Land (71°20′S, 11°35′ E), East Antarctica, to understand dust flux variability, its causes, and potential contribution to radiative forcing during the 20th century in the South Atlantic sector of East Antarctica (SASA). The dust flux profile (sum of 1-25 μm size fractions) reveals three stepwise increase during 1905 -1929 , 1930-1979 , and 1980 with an average of 0.83, 4.7, and 12.88 mg·m −2 ·year −1 , respectively. Our investigation for such dramatic dust flux increase reveals that the increased aridity and favorable wind conditions over Southern South America (SSA), a potential dust source to Antarctica, caused increase in dust production and transport during the late 20th century. The dust flux variability in Southern Hemisphere is concomitant with in-phase relationship between El-Niño Southern Oscillation and Pacific Decadal Oscillations, which influenced the spatial distribution of global wet-dry phase (precipitation pattern). Further, shifting of Southern Annular Mode to positive phase made wind conditions more conducive for long-range dust transport from SSA to coastal Dronning Maud Land region. To the best of our knowledge, this is the first report of past radiative forcing estimates for Antarctica using ice core dust record into a radiative transfer model. Our estimates of radiative forcing corresponding to the enhanced dust flux yield nearly 30% increase in aerosol forcing during the late 20th century. This has resulted 40% decrease in atmospheric cooling rate, which contributed to net atmospheric warming over SASA.Plain Language Summary Atmospheric dust plays an important role in global climate variability through the changes in radiative forcing. Like other parts of Antarctica, the coastal Dronning Maud Land (cDML) in East Antarctic is vulnerable to such changes in radiative balance. However, causative factors for the dust deposition and impact of dust originated radiative forcing on this region remain unknown due to lack of long-term records of dust-derived radiative forcing estimates. Toward this, we have undertaken a systematic ice core-based study from cDML region to reconstruct past records of dust influx, its potential sources, causative factors for the dust production in the Southern Hemispheric continents, and understanding its role on the radiative forcing during the 20th century . Our radiative forcing estimates corresponding to approximately four fold increase in dust influx in the late 20th century indicate an increase in atmospheric warming. The present study would help to better understand the long-term Antarctic climate variability by providing radiative forcing input to the climate models and to improve our current knowledge about the role of dust in contributing to Southern Hemisphere warming during the 20th century.

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Section: Resultsmentioning

confidence: 99%

Enhanced Dust Influx to South Atlantic Sector of Antarctica During the Late‐20th Century: Causes and Contribution to Radiative Forcing

et al. 2020

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“…However, since atmospheric circulation affects the heat and sea ice distribution along the WAP, especially during springtime (Clem et al, 2016), we expect patterns of ENSO and/or SAM to leave a footprint in our spring sea ice IPSO 25 record. Several studies suggest an enhanced influence of ENSO and SAM on Antarctic temperatures with increasing greenhouse gas concentrations, so their relation to sea ice is a crucial factor for sea ice and climate predictions (Rahaman et al, 2019;Stammerjohn et al, 2008b). For example, atmosphere-oceansea ice interactions impact the WAP strongly through increased northerly winds during an in-phase −ENSO/+SAM mode.…”

Section: Sea Ice Evolution and Large-scale Atmospheric Circulation Pamentioning

confidence: 99%

Sea ice dynamics in the Bransfield Strait, Antarctic Peninsula, during the past 240 years: a multi-proxy intercomparison study

et al. 2020

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Abstract. In the last decades, changing climate conditions have had a severe impact on sea ice at the western Antarctic Peninsula (WAP), an area rapidly transforming under global warming. To study the development of spring sea ice and environmental conditions in the pre-satellite era we investigated three short marine sediment cores for their biomarker inventory with a particular focus on the sea ice proxy IPSO25 and micropaleontological proxies. The core sites are located in the Bransfield Strait in shelf to deep basin areas characterized by a complex oceanographic frontal system, coastal influence and sensitivity to large-scale atmospheric circulation patterns. We analyzed geochemical bulk parameters, biomarkers (highly branched isoprenoids, glycerol dialkyl glycerol tetraethers, sterols), and diatom abundances and diversity over the past 240 years and compared them to observational data, sedimentary and ice core climate archives, and results from numerical models. Based on biomarker results we identified four different environmental units characterized by (A) low sea ice cover and high ocean temperatures, (B) moderate sea ice cover with decreasing ocean temperatures, (C) high but variable sea ice cover during intervals of lower ocean temperatures, and (D) extended sea ice cover coincident with a rapid ocean warming. While IPSO25 concentrations correspond quite well to satellite sea ice observations for the past 40 years, we note discrepancies between the biomarker-based sea ice estimates, the long-term model output for the past 240 years, ice core records, and reconstructed atmospheric circulation patterns such as the El Niño–Southern Oscillation (ENSO) and Southern Annular Mode (SAM). We propose that the sea ice biomarker proxies IPSO25 and PIPSO25 are not linearly related to sea ice cover, and, additionally, each core site reflects specific local environmental conditions. High IPSO25 and PIPSO25 values may not be directly interpreted as referring to high spring sea ice cover because variable sea ice conditions and enhanced nutrient supply may affect the production of both the sea-ice-associated and phytoplankton-derived (open marine, pelagic) biomarker lipids. For future interpretations we recommend carefully considering individual biomarker records to distinguish between cold sea-ice-favoring and warm sea-ice-diminishing environmental conditions.

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“…Ding et al, 2011;Schneider et al, 2012;Steig et al, 2013;Bromwich et al, 2013). Furthermore, the near-surface air temperature and precipitation trends observed on the WAIS seem to be linked to the recent deepening of the Amundsen Sea Low (ASL) influencing meridional air mass and heat transport towards West Antarctica (Genthon et al, 2003;Bromwich et al, 2013;Hosking et al, 2013;Burgener et al, 2013;Raphael et al, 2015;. Changes in the absolute depth of the ASL are strongly related to the El Niño-Southern Oscillation (ENSO) and the SAM (Raphael et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Stable water isotopes and accumulation rates in the Union Glacier region, Ellsworth Mountains, West Antarctica, over the last 35 years

Hoffmann

Fernandoy²,

Meyer

et al. 2020

The Cryosphere

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Increased influence of ENSO on Antarctic temperature since the Industrial Era

Cited by 25 publications

References 56 publications

Enhanced Dust Influx to South Atlantic Sector of Antarctica During the Late‐20th Century: Causes and Contribution to Radiative Forcing

Enhanced Dust Influx to South Atlantic Sector of Antarctica During the Late‐20th Century: Causes and Contribution to Radiative Forcing

Sea ice dynamics in the Bransfield Strait, Antarctic Peninsula, during the past 240 years: a multi-proxy intercomparison study

Stable water isotopes and accumulation rates in the Union Glacier region, Ellsworth Mountains, West Antarctica, over the last 35 years

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