Special Issue "Climate Variability in Antarctica and the Southern Hemisphere over the Last Millennia"

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Geophysics".

Deadline for manuscript submissions: closed (15 May 2019).

Special Issue Editors

Guest Editor
Dr. Elizabeth Thomas

British Antarctic Survey, Cambridge, United Kingdom
Website | E-Mail
Interests: ice cores; paleoclimate; Southern Hemisphere climate variability; sea ice; surface mass balance
Guest Editor
Dr. Claire Allen

British Antarctic Survey, Cambridge, United Kingdom
Website | E-Mail
Interests: Antarctic environments and the southern ocean; paleoceanography; high latitude climate variability; ocean-climate interactions; sea-ice; polar marine diatoms

Special Issue Information

Dear Colleagues,

This Special Issue of Geosciences aims to gather high quality original research articles and reviews on climate variability in Antarctica and the Southern Hemisphere over the last millennia.

We would like to invite members of the paleoclimate community to submit articles addressing how large-scale modes of atmospheric and oceanic variability, such as: the Southern Annual Mode (SAM), the Interdecadal Pacific Oscillation (IPO) and El Niño-Southern Oscillation (ENSO); influence the climate in Antarctica and the Southern Hemisphere on both a regional and hemispheric scale. We aim to improve our current understanding of the dominant modes of atmospheric and oceanic variability through evaluation of paleoclimate archives and modelling studies covering the past millennia. We particularly encourage data-model inter comparison and multi-proxy studies.

We encourage submissions based on the following topics:

  • Paleoclimate reconstructions from ice cores
  • Paleoclimate reconstructions from marine sediments
  • Paleoclimate reconstructions from terrestrial records (peat, lake sediments, etc.)
  • Southern Hemisphere modes of climate variability (e.g., SAM and westerly winds)
  • Past surface mass balance and glacial dynamics
  • Past sea ice conditions
  • Past ocean conditions (circulation, meltwater, productivity, etc.)
  • Low-high latitude connections
  • Modelled climate variability
  • Data–model intercomparison

We encourage authors to submit a short abstract, outlining the proposed research article, to the editors prior to submitting a full manuscript to ensure its fit with the objectives of this Special Issue.

Dr. Elizabeth Thomas
Dr. Claire Allen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Geosciences is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Antarctic Climate variability
  • Ice cores
  • Marine records
  • Terrestrial records
  • Climate dynamics
  • Paleoclimate reconstructions
  • Modes of variability (SAM, ENSO, IPO)
  • Ocean/ice-climate interactions
  • Climate- data intercomparisson
  • Southern Hemisphere Westerly Winds

Published Papers (5 papers)

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Research

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Open AccessArticle
Warm Deep Water Variability During the Last Millennium in the CESM–LME: Pre-Industrial Scenario versus Late 20th Century Changes
Geosciences 2019, 9(8), 346; https://doi.org/10.3390/geosciences9080346
Received: 16 May 2019 / Revised: 5 July 2019 / Accepted: 18 July 2019 / Published: 8 August 2019
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Abstract
Water transformation around Antarctica is recognized to significantly impact the climate. It is where the linkage between the upper and lower limbs of the Meridional Overturning Circulation (MOC) takes place by means of dense water formation, which may be affected by rapid climate [...] Read more.
Water transformation around Antarctica is recognized to significantly impact the climate. It is where the linkage between the upper and lower limbs of the Meridional Overturning Circulation (MOC) takes place by means of dense water formation, which may be affected by rapid climate change. Simulation results from the Community Earth System Model Last Millennium Ensemble (CESM–LME) are used to investigate the Weddell Sea Warm Deep Water (WDW) evolution during the Last Millennium (LM). The WDW is the primary heat source for the Weddell Sea (WS) and accounts for 71% of the Weddell Sea Bottom Water (WSBW), which is the regional variety of the Antarctic Bottom Water (AABW)—one of the densest water masses in the ocean bearing directly on the cold deep limb of the MOC. Earth System Models (ESMs) are known to misrepresent the deep layers of the ocean (below 2000 m), hence we aim at the upper component of the deep meridional overturning cell, i.e., the WDW. Salinity and temperature results from the CESM–LME from a transect crossing the WS are evaluated with the Optimum Multiparameter Analysis (OMP) water masses decomposition scheme. It is shown that, after a long–term cooling over the LM, a warming trend takes place at the surface waters in the WS during the 20th century, which is coherent with a global expression. The subsurface layers and. mainly. the WDW domain are subject to the same long–term cooling trend, which is decelerated after 1850 (instead of becoming warmer like the surface waters), probably due interactions with sea ice–insulated ambient waters. The evolution of this anomalous temperature pattern for the WS is clear throughout the three major LM climatic episodes: the Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and late 20th century warming. Along with the continuous decline of WDW core temperatures, heat content in the water mass also decreases by 18.86%. OMP results indicate shoaling and shrinking of the WDW during the LM, with a ~6% decrease in its cross–sectional area. Although the AABW cannot be directly assessed from CESM–LME results, changes in the WDW structure and WS dynamics have the potential to influence the deep/bottom water formation processes and the global MOC. Full article
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Open AccessArticle
South Atlantic Surface Boundary Current System during the Last Millennium in the CESM-LME: The Medieval Climate Anomaly and Little Ice Age
Geosciences 2019, 9(7), 299; https://doi.org/10.3390/geosciences9070299
Received: 16 May 2019 / Revised: 28 June 2019 / Accepted: 3 July 2019 / Published: 9 July 2019
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Abstract
Interocean waters that are carried northward through South Atlantic surface boundary currents get meridionally split between two large-scale systems when meeting the South American coast at the western subtropical portion of the basin. This distribution of the zonal flow along the coast is [...] Read more.
Interocean waters that are carried northward through South Atlantic surface boundary currents get meridionally split between two large-scale systems when meeting the South American coast at the western subtropical portion of the basin. This distribution of the zonal flow along the coast is investigated during the Last Millennium, when natural forcing was key to establish climate variability. Of particular interest are the changes between the contrasting periods of the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). The investigation is conducted with the simulation results from the Community Earth System Model Last Millennium Ensemble (CESM-LME). It is found that the subtropical South Atlantic circulation pattern differs substantially between these natural climatic extremes, especially at the northern boundary of the subtropical gyre, where the westward-flowing southern branch of the South Equatorial Current (sSEC) bifurcates off the South American coast, originating the equatorward-flowing North Brazil Undercurrent (NBUC) and the poleward Brazil Current (BC). It is shown that during the MCA, a weaker anti-cyclonic subtropical gyre circulation took place (inferred from decreased southern sSEC and BC transports), while the equatorward transport of the Meridional Overturning Circulation return flow was increased (intensified northern sSEC and NBUC). The opposite scenario occurs during the LIA: a more vigorous subtropical gyre circulation with decreased northward transport. Full article
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Open AccessArticle
A Validation of ERA5 Reanalysis Data in the Southern Antarctic Peninsula—Ellsworth Land Region, and Its Implications for Ice Core Studies
Geosciences 2019, 9(7), 289; https://doi.org/10.3390/geosciences9070289
Received: 15 May 2019 / Revised: 18 June 2019 / Accepted: 20 June 2019 / Published: 29 June 2019
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Abstract
Climate reanalyses provide key information to calibrate proxy records in regions with scarce direct observations. The climate reanalysis used to perform a proxy calibration should accurately reproduce the local climate variability. Here we present a regional scale evaluation of meteorological parameters using ERA-Interim [...] Read more.
Climate reanalyses provide key information to calibrate proxy records in regions with scarce direct observations. The climate reanalysis used to perform a proxy calibration should accurately reproduce the local climate variability. Here we present a regional scale evaluation of meteorological parameters using ERA-Interim and ERA5 reanalyses compared to in-situ observations from 13 automatic weather stations (AWS), located in the southern Antarctic Peninsula and Ellsworth Land, Antarctica. Both reanalyses seem to perform better in the escarpment area (>1000 m a.s.l) than on the coast. A significant improvement is observed in the performance of ERA5 over ERA-Interim. ERA5 is highly accurate, representing the magnitude and variability of near-surface air temperature and wind regimes. The higher spatial and temporal resolution provided by ERA5 reduces significantly the cold coastal biases identified in ERA-Interim and increases the accuracy representing the wind direction and wind speed in the escarpment. The slight underestimation in the wind speed obtained from the reanalyses could be attributed to an interplay of topographic factors and the effect of local wind regimes. Three sites in this region are highlighted for their potential for ice core studies. These sites are likely to provide accurate proxy calibrations for future palaeoclimatic reconstructions. Full article
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Open AccessArticle
Regional Climate Change Recorded in Moss Oxygen and Carbon Isotopes from a Late Holocene Peat Archive in the Western Antarctic Peninsula
Geosciences 2019, 9(7), 282; https://doi.org/10.3390/geosciences9070282
Received: 15 May 2019 / Revised: 19 June 2019 / Accepted: 22 June 2019 / Published: 26 June 2019
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Abstract
The Antarctic Peninsula (AP) climate is characterized by a high degree of variability, which poses a problem when attempting to put modern change in the context of natural variation. Therefore, novel methods are required to disentangle sometimes conflicting climate records from the region. [...] Read more.
The Antarctic Peninsula (AP) climate is characterized by a high degree of variability, which poses a problem when attempting to put modern change in the context of natural variation. Therefore, novel methods are required to disentangle sometimes conflicting climate records from the region. In recent years, the development of Antarctic moss-cellulose isotopes as a proxy for summer terrestrial growing conditions has become more widespread, with the isotopes Δ13C and δ18O reflecting moss productivity and peatbank moisture conditions, respectively. Here, we used a combined Δ13C and δ18O isotope analysis of moss Chorisodontium aciphyllum cellulose from a peatbank located on Litchfield Island in the western AP to document changes in climate over the last 1700 years. High Δ13C values (>15‰) indicate warm and productive conditions on Litchfield Island from 1600 to 1350 cal yr BP (350 to 600 AD) and over the last 100 years. The δ18O record shows two distinct intervals of dry conditions at 1350–1000 cal yr BP (600–950 AD) and at 500–0 cal yr BP (1450–1950 AD). Our record indicates that terrestrial ecosystems in the AP have responded to regional climate driven by atmospheric circulation, such as the southern annular mode (SAM) and, to a lesser extent, changes in ocean circulation. Full article
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Review

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Open AccessReview
Back to the Future: Using Long-Term Observational and Paleo-Proxy Reconstructions to Improve Model Projections of Antarctic Climate
Geosciences 2019, 9(6), 255; https://doi.org/10.3390/geosciences9060255
Received: 15 May 2019 / Revised: 31 May 2019 / Accepted: 4 June 2019 / Published: 7 June 2019
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Abstract
Quantitative estimates of future Antarctic climate change are derived from numerical global climate models. Evaluation of the reliability of climate model projections involves many lines of evidence on past performance combined with knowledge of the processes that need to be represented. Routine model [...] Read more.
Quantitative estimates of future Antarctic climate change are derived from numerical global climate models. Evaluation of the reliability of climate model projections involves many lines of evidence on past performance combined with knowledge of the processes that need to be represented. Routine model evaluation is mainly based on the modern observational period, which started with the establishment of a network of Antarctic weather stations in 1957/58. This period is too short to evaluate many fundamental aspects of the Antarctic and Southern Ocean climate system, such as decadal-to-century time-scale climate variability and trends. To help address this gap, we present a new evaluation of potential ways in which long-term observational and paleo-proxy reconstructions may be used, with a particular focus on improving projections. A wide range of data sources and time periods is included, ranging from ship observations of the early 20th century to ice core records spanning hundreds to hundreds of thousands of years to sediment records dating back 34 million years. We conclude that paleo-proxy records and long-term observational datasets are an underused resource in terms of strategies for improving Antarctic climate projections for the 21st century and beyond. We identify priorities and suggest next steps to addressing this. Full article
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