The Medieval Climate Anomaly in Antarctica

Palaeogeography, Palaeoclimatology, Palaeoecology 532 (2019) 109251

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Review article

The Medieval Climate Anomaly in Antarctica a,⁎

b

Sebastian Lüning , Mariusz Gałka , Fritz Vahrenholt a b c

T

c

Institute for Hydrography, Geoecology and Climate Sciences, Hauptstraße 47, 6315 Ägeri, Switzerland Department of Geobotany and Plant Ecology, Faculty of Biology and Environmental Protection, University of Lodz, 12/16 Banacha Str., Lodz, Poland Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany

A B S T R A C T

The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 CE. Here we are mapping the MCA across the Antarctic region based on the analysis of published palaeotemperature proxy data from 60 sites. In addition to the conventionally used ice core data, we are integrating temperature proxy records from marine and terrestrial sediment cores as well as radiocarbon ages of glacier moraines and elephant seal colonies. A generally warm MCA compared to the subsequent Little Ice Age (LIA) was found for the Subantarctic Islands south of the Antarctic Convergence, the Antarctic Peninsula, Victoria Land and central West Antarctica. A somewhat less clear MCA warm signal was detected for the majority of East Antarctica. MCA cooling occurred in the Ross Ice Shelf region, and probably in the Weddell Sea and on Filchner-Ronne Ice Shelf. Spatial distribution of MCA cooling and warming follows modern dipole patterns, as reflected by areas of opposing temperature trends. Main drivers of the multi-centennial scale climate variability appear to be the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO) which are linked to solar activity changes by nonlinear dynamics.

1. Introduction Until recently, the Antarctic Peninsula and West Antarctica were among the most rapidly warming regions on Earth. Between the 1950s and 1990s temperatures on the Antarctic Peninsula increased by more than 0.3 °C/decade (Stenni et al., 2017; Turner et al., 2016; Vaughan et al., 2003), with even higher warming rates reported for Byrd Station in West Antarctica (Bromwich et al., 2013; Bunde et al., 2014; Nicolas and Bromwich, 2014). Since the late 1990s, however, this warming has essentially stalled. Rapid cooling of nearly 0.5 °C per decade occurred on the Antarctic Peninsula (Favier et al., 2017; Fernandoy et al., 2018; Turner et al., 2016). This already impacted the cryosphere in parts of the Antarctic Peninsula, including slow-down of glacier recession, surface mass gains of the peripheral glaciers and a thinning of the active layer of permafrost in the northern Antarctic Peninsula islands (Engel et al., 2018; Oliva et al., 2017; Seehaus et al., 2018). At the same time, temperatures in West Antarctica over the past two decades appear to have plateaued or slightly cooled (Bromwich et al., 2013; Jones et al., 2016; Steig et al., 2009). However, temperature records in West Antarctica are few, often discontinuous and show opposing trends from location to location (Shuman and Stearns, 2001) which complicates modern trend analysis in this part of Antarctica. In contrast, East Antarctica has not experienced any significant temperature change since the 1950s (e.g. Yang et al., 2018) and some areas appear to have even cooled during the most recent decades (Clem et al., 2018; Favier et al., 2017; Jones et al., 2016; Marshall et al., 2014; Nicolas and Bromwich,

⁎

2014; O'Donnell et al., 2011; Ramesh and Soni, 2018). Cooling and an increase in snowfall in East Antarctica seems to have led to a gain in ice sheet mass and thickening of ice rises over the past 15 years (Goel et al., 2017; Martin-Español et al., 2017; Philippe et al., 2016; Zwally et al., 2015). East Antarctic marine-terminating glaciers show no systematic change over the past 50 years (Lovell et al., 2017). Lastly, also the surface layers of the Southern Ocean south of 45°S has predominantly cooled over that past three decades (Armour et al., 2016; Fan et al., 2014; Kusahara et al., 2017; Latif et al., 2017), whilst the subpolar abyssal waters are warming (Sallée, 2018). On a century scale, no significant statistical warming trend can be found for most Antarctic stations (Ludescher et al., 2016). Antarctic temperatures appear to be still well within the range of natural variability. Natural climate factors such as multidecadal ocean cycles still dominate over anthropogenic climate drivers, such as CO2 (Chylek et al., 2010; Favier et al., 2017; Jones et al., 2016; Ludescher et al., 2016; Smith and Polvani, 2017; Steig et al., 2013; Turner et al., 2016). On interannual to decadal scale, a general anti-phase has been observed between the temperatures of East Antarctica and Antarctic Peninsula/West Antarctica (Schneider et al., 2006). The Transantarctic Mountains act as a dividing line for the temperature trends of the two regions, reflecting the topographic constraint on warm air advection from the Amundsen Sea basin (Nicolas and Bromwich, 2014). Unfortunately, climate models still fail to reproduce the regional Antarctic temperature and snowfall development and generally overestimate the magnitude of the forced response (Favier et al., 2017; Jones et al., 2016;

Corresponding author. E-mail addresses: [email protected] (S. Lüning), [email protected] (M. Gałka), [email protected] (F. Vahrenholt).

https://doi.org/10.1016/j.palaeo.2019.109251 Received 2 April 2019; Received in revised form 24 June 2019; Accepted 25 June 2019 Available online 29 June 2019 0031-0182/ © 2019 Elsevier B.V. All rights reserved.

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(IOD) and the Atlantic Multidecadal Oscillation (AMO) (e.g. Li et al., 2014; Zhang et al., 2015). The various ocean cycles are partly interlinked (Wyatt and Curry, 2014). Other factors that may have affected pre-industrial climate change are solar activity changes (e.g. Barbara et al., 2016; Bentley et al., 2009; Christ et al., 2015; Costa et al., 2007) and volcanic eruptions (e.g. Yang and Xiao, 2018). A detailed overview of important potential drivers of natural climate variability in Antarctica can be found in Supplement Texts 1a–h.

Tang et al., 2018). A better understanding of natural variability on multi-decadal, centennial and millennial-scales will help to further refine these models and calibrate them with the pre-industrial climate development by way of hindcasts (Fogt et al., 2017; Goosse, 2017; Mayewski et al., 2017). This paper focuses on the Medieval Climate Anomaly (MCA), a distinctive rapid climate fluctuation that has been documented from many parts of the world. The best-studied region is the mid and high latitude North Atlantic realm where numerous studies documented a pronounced warm phase during the MCA. This historically led to the introduction of the term ‘Early Medieval Warm Epoch’ (Lamb, 1965), which subsequently changed in the literature to ‘Medieval Warm Period’ (MWP), and finally to ‘Medieval Climate Anomaly’ (MCA) (e.g. Grove and Switsur, 1994). It is generally agreed today that the core period of the MCA comprises ca. 1000–1200 CE. Nevertheless, different time schemes and durations have historically been used in the literature, with the widest scheme comprising 800–1300 CE (e.g. Crowley and Lowery, 2000; Esper and Frank, 2009; Mann et al., 2009). Here we concentrate on the MCA core period 1000–1200 CE and attempt to map temperature patterns across the Antarctic region based on proxy data from 60 published sites (Fig. 1). We investigate which parts of Antarctica experienced warming during the MCA and which areas cooled. Likely drivers of the observed pre-industrial south polar climate change of the past 1500 years are discussed. A recent Antarctic temperature reconstruction by Stenni et al. (2017) based solely on ice cores suggests a warm MCA that is followed by significant cooling of the Little Ice Age (LIA) after 1250 CE that lasts until 1950 CE. Overall, the authors note a long-term cooling trend for the last 2000 years. We are complementing the ice core data with other palaeotemperature proxies from marine and terrestrial sediment cores as well as radiocarbon ages of glacier moraines, elephant seal colonies and penguin rookeries. Whilst this approach adds more data points, it also diversifies the source of palaeoclimatic information. A better understanding of the preindustrial Antarctic climate history, and in particular of natural warm phases, provides crucial input for climate model calibration and refinement. This compilation also highlights major data gaps, which future studies hopefully will be able to infill.

4. Material and methods 4.1. Literature review The mapping project is based on a comprehensive literature screening process during which all available published Antarctic palaeotemperature case studies were evaluated towards their temporal coverage, types of climate information and data resolution. Suitable papers including the MCA core period 1000–1200 CE were earmarked for a thorough analysis. Generally, studies should contain at least one palaeotemperature data point within the MCA period, either quantitative or just qualitative. A total of 60 Antarctic localities with one or more MCA palaeotemperature proxy curves were identified (Figs. 1–3; Tables 1 and S1). This Antarctic review forms part of an attempt to palaeoclimatically map the MCA on a global scale (Lüning et al., 2019a; Lüning et al., 2018; Lüning et al., 2019b; Lüning et al., 2017). 4.2. Palaeoclimate archives and data types MCA climate reconstructions of the publications high-graded by the screening process comprised of several natural archives, namely (1) sediment cores from marine, lakes, peatlands, (2) ice cores from the Antarctic Ice Sheet and smaller peripheral ice caps, (3) dating of glacier moraines and elephant seal colonies. Data types include (a) palaeontology (diatoms, palynology), (b) inorganic geochemistry (δ18O, δ2H, deuterium excess in ice cores; δ18O in foraminifera and lake carbonates; biogenic silica, elemental sediment composition; ikaite crystallization), (c) organic geochemistry (total organic carbon; loss-on-ignition; Tex86 sea surface temperature), (d) geophysics (magnetic susceptibility, radio‑carbon 14C dating of moss and elephant seal skin), (e) sedimentology (sediment petrography, grain size), and (f) ice microscopy (air bubble density).

2. Modern climate setting of Antarctica Antarctica is positioned asymmetrically around the South Pole and lies largely south of the Antarctic Circle (Fig. 1). About 98% of Antarctica is covered by the Antarctic ice sheet which has an average thickness of more than 1800 m. The average height of Antarctica is 1958 m, which represents the highest average elevation of all the continents. Antarctica is also the coldest, driest, and windiest continent of all. It is surrounded by the Southern Ocean which is connected northwards to the Pacific, Atlantic and Indian Oceans. The Antarctic coastal zones are subjected to east wind drift. North of the Antarctic Divergence (~60°S), a west wind drift prevails that drives the Antarctic Circumpolar Current. Further north, between latitudes 50°S and 60°S, lies the Antarctic Convergence which is also known as Antarctic Polar Front (Fig. 1). Here, cold waters from the Antarctic region sink beneath the warm waters from the middle latitudes, forming the Antarctic intermediate water.

4.3. Data processing and visualisation 4.3.1. Qualitative Key information of the identified publications were captured on a georeferenced online map which is available at http://t1p.de/mwp. The MCA palaeotemperature was visually assessed and compared to the phases preceding and following the anomaly. The MCA trend was colour-coded with red dots marking a trend towards warmer conditions whilst blue dots represent cooling. In some cases the centuries preceding the MCA were as warm as the MCA itself. In this case the MCA was compared to the subsequent centuries of the LIA. The colour-coding provides much-needed initial orientation in the complex global MCA climate puzzle.

3. Natural climate drivers of Antarctic temperature variability

4.3.2. Quantitative In order to robustly document, visualise and analyse MCA palaeoclimatic variability, all relevant climate curve data were collected in digital form for flexible plotting and curve correlation. The tabulated data were retrieved (a) from palaeoclimate online data repositories (mainly Pangaea, NOAA's National Climatic Data Center NCDC and data supplements of papers), (b) from authors by email request and (c) by digitizing and vectorising using WebPlotDigitizer (https:// automeris.io/WebPlotDigitizer/). Data sources for each site are listed in Table S1. All curve data have been loaded into Lloyd's Register's

Temperatures, precipitation and weather extremes across the globe are characterized by systematic variability that is to a large extent driven by multidecadal and shorter-term ocean cycles. In the case of Antarctica, the most important drivers are the Southern Annular Mode (SAM), El Niño Southern Oscillation (ENSO), the Southern Oscillation Index (SOI) and the Interdecadal Pacific Oscillation (IPO) (e.g. Bukatov et al., 2016; Ekaykin et al., 2014; Turner et al., 2014). Secondary Antarctic multidecadal climate factors are the Indian Ocean Dipole 2

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Fig. 1. Location map of studied sites. Key to site numbers in Table 1. Zoom location maps of the Antarctic Peninsula and Victorialand are shown in Figs. 2 and 3. Brown lines connect the sites shown in the correlation panels in Supplement Figs. S2–S12. Basemap: Quantarctica. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

generate comprehensive and meaningful statistics for the Antarctic MCA dataset. Particularly challenging are differences in data resolution and age shifts due to model uncertainties. Nevertheless, some basic statistical analyses have been carried out to qualitatively support the trend discussion (Table S2). Proxy averages were calculated for the four time windows 500–900 CE, 950–1250 CE (MCA plus some error margin), 1250–1500 CE and 1500–1800 CE. Data were homogenized for time steps of 25 years, except for lower resolution data for which longer time steps of 50 years were chosen. Proxy data were interpolated where necessary. Standard deviations were calculated for 95% (2σ) confidence.

software IC™ which serves as a common database and correlation tool in the MCA mapping project. IC™ was originally developed for geological well correlations in the areas of water, minerals and petroleum exploration (e.g. Luthi, 2001). The software reliably handles large amounts of fully customizable curve data types related to georeferenced wells. By way of technology transfer we are introducing well correlation software to the field of the climate sciences which allows fast and flexible comparison of climate curves. Another advantage is the advanced visualisation and shading of peak and trough curve anomalies, a functionality which lacks in most standard spreadsheet software packages. See Lüning et al. (2017) for details on the workflow. Location maps were produced using the Quantarctica Geographic Information System (GIS) package provided by the Norwegian Polar Institute, based on the open source QGIS software.

4.4. Challenges

4.3.3. Trend statistics Enormous heterogeneity of the proxy data makes it complicated to

Like any other regional palaeoclimatic synthesis, the current Antarctic palaeotemperature MCA mapping effort is subjected to a number of challenges. Palaeoclimatology is not an exact mathematical 3

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Fig. 2. Zoomed location map of the Antarctic Peninsula sites. See Fig. 1 for Antarctic overview map.

column that lists for each site the number of age markers for the last 2500 years.

science, nevertheless provides crucial data for the palaeoclimatological context and model calibration. A probabilistic approach is needed whereby the most likely scenario is selected from the set of available proxies.

4.4.3. Validity of palaeoclimate interpretation Paleoclimate interpretations are based on proxies which often leave room for alternative interpretations. It is therefore not uncommon that climate proxy data may undergo re-interpretation by other researchers subsequent to their publication. Examples are oxygen and carbon isotope proxies whose suitability as precipitation and rainfall proxies depends often on local factors, leading to different views among researchers.

4.4.1. Low resolution palaeoclimate data The core phase of the MCA is only 200 years long and may not be represented by a data point in studies of low resolution data. In particular, this is a problem in data series covering the entire Holocene or more which often have only few data points per millennium. In obvious cases, such analyses have been excluded from the present analysis.

4.4.4. Conflicting information from multiple proxies In some case studies, proxies that usually represent similar climate parameters yield conflicting results. In such cases, the most likely correct scenario has to be selected, based on the comparison with neighbouring case studies and the regional context.

4.4.2. Limited age control, faulty age models Even though a large number of climatic data points may exist over the past millennium, age control can be a problem. Among the reasons are (a) a low number of dated horizons, (b) last age in a multi-millennial-year section much older than the MCA, (c) scatter in obtained ages and (d) general dating and correction problems. As a possible result, observed climate anomalies may be age-shifted, causing problems with calculating regional multi-study average values. Table S1 contains a

4.4.5. Seasonal vs. annual significance Attention has to be paid to seasonally restricted proxies. Some data 4

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Fig. 3. Zoomed location map of Victoria Land, Ross Ice Shelf and Ross Sea sites. See Fig. 1 for Antarctic overview map.

carbon may also occur. Accumulation rates in the various ice cores differ and may impact data resolution. For example, rates in Vostok are several times lower than in Law Dome. Whilst the covariance between δ18O and temperature is generally reproduced in isotope-enabled models, it is generally weak and characterized by a strong spatial heterogeneity, as well as changes over time with no apparent link with forcings (Klein et al., 2018). Furthermore, stable oxygen isotope records in ice cores are potentially vulnerable to post-deposition alteration processes, especially in low accumulation areas such as the East Antarctic Ice Sheet (Casado et al., 2017; Laepple et al., 2018; Münch et al., 2016, 2017). Ice trench studies at Kohnen Station in Dronning Maud Land revealed a surprisingly high horizontal isotopic variability caused by local stratigraphic noise, indicating that

conflicts may e.g. be explained by winter rain vs. summer rain vs. extreme precipitation which may all be captured by different proxies and have different climatic meanings.

4.4.6. Other issues Due to carbon-14 depletion in Antarctic waters, all radiocarbon dates from the Antarctic must be corrected by a factor which accounts for the pool of old carbon in Antarctic waters. If uncorrected, the Antarctic reservoir effect yields anomalously old surface ages (Hall et al., 2010a). Here we are using the originally published chronologies which may lead to issues related to different calibration curves and different software. 2σ error ranges of radiocarbon ages stated by authors are typically between ± 30–100 years. Contamination by dead 5

Lützow Holm Bay Dome Fuji Ice Core Plateau Remote Ice Core Lake Terrasovoje AM02 core Amery Ice Shelf Kirisjes Pond Co1010 Zolotov Island Long Peninsula Dome B Ice Core Vostok Ice Core EPICA Dome Concordia (“Dome C”) Ice Core

Midge Lake JPC2 JPC38 Hidden Lake

16 17 18 19

34 35 36 37 38 39 40 41 42 43 44 45

Ardley Island Yanou Lake

14 15

Anvers Island sites near U.S. Palmer Station Litchfield Island ODP 1098 Bigo Bay KC-55 Müller Ice Shelf Rothera Point JPC43 Berkner Island Ice Core Dronning Maud Land Traverse Schirmacher Oasis

Collins Ice Cap

13

22 23 24 25 26 27 28 29 30 31 32 33

Fan Lake Signy Island A9-EB2, eastern Bransfield Basin JPC24 GEBRA-1 PS69/335

7 8 9 10 11 12

Herbert Sound JRI ice core

Kerguelen Islands Ile de la Possession TN057-17 PS1652-2 PS2102-2 Hamberg Lakes

1 2 3 4 5 6

20 21

Locality

No.

6 East Antarctica East Antarctica East Antarctica Prydz Bay, East Prydz Bay, East Prydz Bay, East Prydz Bay, East Prydz Bay, East Prydz Bay, East East Antarctica East Antarctica East Antarctica Antarctica Antarctica Antarctica Antarctica Antarctica Antarctica

Annenkov Island, Antarctic Islands Antarctic Islands Antarctic Peninsula Bransfield Basin, Antarctic Peninsula Antarctic Peninsula King George Island, Antarctic Peninsula King George Island, Antarctic Peninsula Antarctic Peninsula King George Island, Antarctic Peninsula Livingston Island, Antarctic Peninsula Firth of Tay, Antarctic Peninsula Antarctic Peninsula James Ross Island, Antarctic Peninsula Antarctic Peninsula James Ross Island, Antarctic Peninsula Antarctic Peninsula Antarctic Peninsula Antarctic Peninsula Antarctic Peninsula Antarctic Peninsula Antarctic Peninsula Lallemand Fjord, Antarctic Peninsula Marguerite Bay, Antarctic Peninsula Neny Fjord, Antarctic Peninsula Ronne & Filchner Ice Shelf East Antarctica East Antarctica

Antarctic Islands Antarctic Islands Antarctic Islands Near Bouvet Island, Antarctic Islands Near Bouvet Island, Antarctic Islands South Georgia, Antarctic Islands

Region

Lake core Ice core Ice core Lake core Marine core Lake core Marine core Lake core Lake core Ice core Ice core Ice core

Glacier dating Glacier dating Peat core Marine core Marine core Marine core Marine core Glacier dating Marine core Ice core Ice core Lake core

Marine core Ice core

Lake core Marine core Marine core Lake core

Lake core Lake core

Glacier dating

Lake core Lake core Marine core Marine core Marine core Marine core

Glacier dating Peat core Marine core Marine core Marine core Lake core

Archive

Dating mosses and shells Dating mosses Peat accumulation rate Ms, Tex86, benthic foraminifera isotopes Biogenic opal, TOC TOC Sedimentology, geochem., forams. Dating mosses ms δ2H, δ18O δ18O TOC, BSi, grain size, elemental geochem. Diatoms, sedimentology, geochem. δ18O δ18O Diatoms, geochem. Diatoms Diatoms TOC P2O5 P/Al δ2H δ2H δ2H

Diatoms, petrography δ2H

LOI TOC, Ikaite crystallization Diatoms Loss on Ignition

P2O5 GDGTs

Dating mosses

Palynology, GDGTs δ18O of authigenic lake carbonate, mites ms TOC Diatoms Elemental ratios, TOC, opal, grain size

Moraine dating Diatoms Diatoms Diatoms Diatoms Ti as glacial activity proxy

Proxies

Tavernier et al. (2014) Horiuchi et al. (2008) Mosley-Thompson (1996) Wagner et al. (2004) Hemer and Harris (2003) Verleyen et al. (2004) Berg et al. (2010) Huang et al. (2011) Gao et al. (2019) Masson et al. (2000), Vimeux et al. (2001) Masson et al. (2000), Vimeux et al. (2001) Masson et al. (2000), Masson-Delmotte et al. (2004)

(continued on next page)

Hall et al. (2010b) Yu et al. (2016) Stelling et al. (2018) Domack and Mayewski (1999), Shevenell and Kennett (2002), Shevenell et al. (2011) Kim et al. (2018) Christ et al. (2015) Domack et al. (1995) Guglielmin et al. (2016) Allen et al. (2010) Mulvaney et al. (2002), Graf et al. (2006) Graf et al. (2002) Govil et al. (2016)

Minzoni et al. (2015) Mulvaney et al. (2012), Abram et al. (2013)

Björck et al. (1991) Lu et al. (2012) Barbara et al. (2016) Zale (1994)

Sun et al. (2000), Huang et al. (2011), Liu et al. (2005) Roberts et al. (2017)

Hall (2007)

Jomelli et al. (2017) Ooms et al. (2011) Nielsen et al. (2004), Divine et al. (2010) Xiao et al. (2016) Xiao et al. (2016) Clapperton et al. (1989), van der Bilt et al. (2017); other South Georgia: Oppedal et al. (2018) Strother et al. (2015), Foster et al. (2016) Noon et al. (2003), Hodgson and Convey (2005) Khim et al. (2002) Barnard et al. (2014) Bárcena et al. (1998) Hass et al. (2010), Monien et al. (2011)

Reference

Table 1 MCA study sites in the Antarctic region. Key to climate proxy abbreviations: δ2H = deuterium, ms = magnetic susceptibility, TOC = total organic carbon, LOI = loss on ignition, GDGTs = glycerol dialkyl glycerol tetraethers.

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Morgan and Ommen (1997), Dahl-Jensen et al. (1999), Roberts et al. (2001), Plummer et al. (2012), Goosse et al. (2004) PAGES 2k Consortium (2017), Mezgec et al. (2017) Mezgec et al. (2017) Mezgec et al. (2017) Baroni and Orombelli (1994b) Baroni and Orombelli (1994a) Hall et al. (2006) Leventer et al. (1993) Bertler et al. (2011) Hall and Denton (2002) Steig et al. (1998) Bertler et al. (2018) Mayewski et al. (2013) Mayewski et al. (1995), Masson et al. (2000) Steig et al. (2013), Fegyveresi et al. (2016), Fudge et al. (2016)

isotope records from individual ice cores have to be treated with caution with regards to temperature interpretations (Münch et al., 2016, 2017; Münch and Laepple, 2018). Significant metamorphism on the surface snow isotopic signal has also been documented for Dome C (Casado et al., 2017). Generally, single ice core records in East Antarctica appear to suffer from a very low signal-to-noise ratio, therefore it is better to work with local or regional stacks (pers. comm. Alexey Ekaykin, Nov. 2017).

A total of 60 study sites have been identified in the Antarctic region, comprising regional clusters in the western Antarctic Peninsula, Prydz Bay and Victoria Land (Figs. 1–3; Table 1). Detailed site descriptions and palaeo-temperature correlation panels can be found in the Supporting Information to this paper (texts and Figs. S2–S12, Table S1). A correlation panel with 6 representative sites from the study area as well as the Antarctic temperature reconstruction of Stenni et al. (2017) is illustrated in Fig. 4 to facilitate the discussion. 6. Regional MCA temperature trends 6.1. Antarctic Peninsula and Weddell Sea

2

δ O, δ H, deuterium excess Diatoms Diatoms Moraine dating C14 dating of penguin remains Dating elephant seal skin Diatoms δ2H Glacial topography ages δ2H, δ18O δ2H δ2H, δ18O δ2H δ18O, air bubble density

The vast majority of sites in the Antarctic Peninsula region document a warm phase for the MCA (Fig. 5; texts and Figs. S3–S7 in supplement to this paper). Marine and lake sediment cores typically show enrichment in organic matter, reflecting higher biological productivity in a warmer, more life-friendly climate (sites 9–12, 17, 27, 30). A warm MCA is also supported by TEX86 temperatures (Site 25) and reduced sea ice (sites 11, 18). Glaciers typically retreated during the MCA and readvanced during the subsequent Little Ice Age as indicated by radiocarbon dating of moss (sites 13, 22, 23, 29). Only two sites deviate from this regional trend. The James Ross Island ice core (Site 21) documents a rather cold temperature during the MCA (Figs. 5, S6). The discrepancy may be due to issues with the age model which is currently under revision. Another possible reason could be noise in the temperature signal because the Ross Island interpretation is based on a single long ice core rather than a stack of local cores. Modelling by Davies et al. (2014) demonstrates that the Ross Island glaciers reached their maximum Holocene extent around 1700 CE during the peak of the Little Ice Age. Glacier advance phases commencing as early as at the end of the MCA were described from the Antarctic Peninsula based on regional moss data (Guglielmin et al., 2016; Hall, 2007; Hall et al., 2010b; Yu et al., 2016). Another deviation from the regional Antarctic Peninsula (AP) trend occurs in Herbert Sound (Site 20) which forms a narrow embayment on the northern side of James Ross Island (Fig. 2). The MCA appears to have been cold here (Figs. 5, S6). A possible interpretation may be the fjord nature of the embayment which is likely to have received increased amounts of cold melt water during the MCA due to more intense summer melting of the ice cap on James Ross Island under a regionally warmer MCA climate on the Antarctic Peninsula. Notably, most MCA palaeoclimate data come from the western side of the Antarctic Peninsula and its northernmost tip (Figs. 5, 6). Studies from the central and southern Weddell Sea are mostly lacking. James Ross Island forms an exception because it lies on the Weddell Sea side of the AP and provides the southeastern most datapoint for the Peninsula. The signs of a colder MCA in the two James Ross Island sites 20 and 21 could therefore also point to a climatic MCA regime shift between the western AP/Bellingshausen Sea and the eastern AP/Weddell Sea. Such a pattern with opposing SST trends is known from the modern ENSO dynamics and has been termed ‘Antarctic Dipole’ (Dash et al., 2013; Yuan, 2004). The only other data point available from the wider region is the Berkner Island ice core (Site 31) from the Filchner-Ronne Ice Shelf, just south of the Wedddel Sea (Fig. 1). The ice core shows MCA

Ice core Marine core Marine core Glacier dating C14 ages Seal skin dating Marine core Ice core Glacier dating Ice core Ice core Ice core Ice core Ice core Talos Dome, East Antarctic Plateau Cape Hallett, western Ross Sea Woods Bay, western Ross SEa Terra Nova Bay, Victoria Land Victoria Land coast Western Ross Sea Granite Harbor, McMurdo Sound McMurdy Dry Valleys Western Ross Sea coast East Antarctica Roosevelt Island, eastern Ross Sea West Antarctica Transantarctic Mountains West Antarctica

Ice core

47 48 49 50 51 52 53 54 55 56 57 58 59 60

Dome Summit South (DSS) - Law Dome Ice Core TALDICE Ice Core WRS_CH WRS_WB Edmonson Point Glacier Prior Island Western Ross Sea KC208.09 Victoria Lower Glacier Ice Core Wilson Piedmont Glacier Taylor Dome Ice Core RICE Ice Core Siple Dome Ice Core Dominion Range Ice Core WAIS Divide Ice Core 46

East Antarctica

5. Results

18

δ H, δ O 18 2

Locality No.

Table 1 (continued)

Region

Archive

Proxies

Reference

S. Lüning, et al.

7

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Fig. 4. Temperature development in the Antarctic region during the past 1500 years based on palaeoclimate proxies of selected study sites. 7: Fan Lake (Strother et al., 2015), 25: ODP 1098 (Domack and Mayewski, 1999; Shevenell et al., 2011; Shevenell and Kennett, 2002), 31: Berkner Island (Mulvaney et al., 2002), 45: EPICA Dome C (Masson-Delmotte et al., 2004), 49: Woods Bay (Mezgec et al., 2017), 57: RICE ice core (Bertler et al., 2018), whole Antarctica (Stenni et al., 2017: composite-plus-scaling CPS reconstruction). Location maps in Figs. 1–3.

series from Dronning Maud Land (Site 32) indicates that the oxygen and deuterium isotope records can significantly differ between nearby sites (Fig. S8), which is in line with recent ice trench studies on modern ice accumulations in the same region, pointing to abundant local stratigraphic noise (Münch et al., 2016, 2017). MCA warming is most pronounced in Dronning Maud core 27–07 and least developed in 27–17 (Graf et al., 2002) (Fig. S8). Similar variability exists at Vostok (Site 44) where different sets of shallow and deep ice cores yield different representations of the MCA warming which in some cases is longer and more pronounced, and yet in other cases shorter and less developed (Fig. S10). Modern analogue studies at EPICA Dome C (Site 45) point to the risk of post-depositional alterations in the deuterium isotope record (Casado et al., 2017). In Law Dome (Site 46) the deuterium excess data suggest high evaporation and warm conditions for the majority and central part of the MCA, whilst oxygen isotopes only indicate warmth during the first half of the MCA (Fig. S10). The difference in deuterium excess compared to δ18O might reflect the different conditions on the continent compared to the ocean where the evaporation takes place (pers. comm. Hugues Goosse, Nov. 2017). Deuterium excess is a proxy of evaporative conditions (SST, relative humidity and wind speed) at moisture source regions and can be considered as an integrated tracer of the hydrological cycle (Mezgec et al., 2017). The oxygen isotopes in the Plateau Remote ice core (Site 36) show the opposite of Law Dome, i.e. a cold first half of the MCA and a warmer second half (Fig. S8). Uncertainties in the age model of these ice cores may be responsible for some of these trend discrepancies. Many of the East Antarctic ice cores have a pronounced cooling shift around the end of the MCA which could be used to provisionally align the records when the age models are uncertain. The ice core dating by volcanic events has evolved over the years, meaning that older age models may need revision in light of updated volcanic eruption chronologies (e.g. Sigl et al., 2015). Pattern matching and cyclostratigraphy of water isotope record may be necessary to further refine the correlation of the various ice cores in East Antarctica on decadal time scales. Most sediment cores in the Prydz Bay and Amery Ice shelf region

cooling, therefore providing further evidence that the Weddell Sea might have cooled as a whole during the MCA (Figs. 4, 6). 6.2. Subantarctic Islands The majority of studies from the Subantarctic Islands show a warm MCA (Fig. 6). Glaciers on the islands retracted during the MCA and expanded during the subsequent Little Ice Age as documented by moraine dating (Kerguelen Islands, Site 1) and elemental geochemistry in pro-glacial lakes (South Georgia, Site 6) (Text and Fig. S2). Temperatures were elevated and sea ice reduced as interpreted from diatoms, pollen, moss mites and stable oxygen isotopes in marine and lake sediment cores (sites 3–5, 7, 8; Bouvet Island, South Georgia, South Orkneys) (Figs. 4, S2). All of these sites are located south of the Antarctic Convergence, or very close to it (Site 3) (Fig. 6). An exception is the cold MCA that was documented in a peat core study from Ile de la Possession in the Crozet Archipelago (Site 2) (Figs. 6, S2). This site lies north of the Antarctic Convergence and may therefore represent a different palaeoclimatic regime. 6.3. East Antarctica Most studies from East Antarctica generally suggest a warm MCA, even though the reconstructed climate signal is noisier than in other parts of the Antarctic region. The available data consist of ice core sites on the East Antarctic Ice Sheet as well as marine and lake sediment core locations in the coastal zone (Fig. 1). The ice cores generally document MCA warming (sites 32, 35, 43–45), nevertheless showing significant variability (Figs. 4, 6; Texts and Figs. S8–S11). This in part may be related to the low snow accumulation rates in East Antarctica which complicate dating and in some cases may have led to post-depositional alterations in the water isotope composition (Casado et al., 2017; Münch et al., 2016, 2017). A pronounced and extensive MCA warm phase occurs in Dome Fuji (Site 35), whilst the warming appears somewhat shorter in Dome B (Site 43) and EPICA Dome C (Site 45) (Figs. 4, S8, S10). An ice core 8

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Fig. 5. Temperature trends during the Medieval Climate Anomaly in the Antarctic Peninsula region. Site descriptions and climate proxy correlation panels in Supplement (texts and Figs. S3–S5). Antarctic trends overview map in Fig. 6.

reduced glacier length during the MCA, followed by glacier advance in Little Ice Age (sites 50 and 55). Likewise, elephant seal colonies existed during the MCA along the southern Victoria Land Coast whilst they had to be abandoned in the Little Ice Age due to unfavourable cooling (Site 52). Notably, these breeding grounds have not yet been resettled until present-day. Diatoms in the marine WRS_CH core (Site 48) at first glance suggest cooling for the MCA (Figs. 7, S11). However, comparison with the nearby Site 49 suggests that the chronology in Site 48 may be shifted. The warm-to-cold shift documented in Site 48 may in fact correspond to the end of the MCA and appears to be 350 years too old. This is well within the uncertainty range of 600 years which Mezgec et al. (2017) cite in their paper. In an alternative interpretation, the observed discrepancy may be related to differences in katabatic wind strengths and the efficiency of the polynyas at sites 48 and 49, which influences the abundance of the sea ice proxy form Fragilariopsis curta (pers. comm. Barbara Stenni, Nov. 2017). The Ross Ice Shelf appears to have been cooling during the MCA, as evidenced by the four ice cores Taylor Dome, RICE, Siple Dome and

suggest a warm MCA (Fig. 6). Biological activity and coastal lake levels were higher (sites 39 and 40) and the sea ice season may have been shorter (Site 38, note low data resolution and age model uncertainties) (Fig. S9). A cold MCA has been interpreted based on reduced organic content in a proglacial lake in the Schirmacher Oasis (Site 33) (Fig. S8). It is speculated that this reflects increased cold meltwater influx from the nearby glaciers in a regionally warmer climate. Interpretability of two other records in coastal East Antarctic study locations, Lützow Holm Bay (Site 34) and Lake Terrasovoje (Site 37) is limited due to a condensed section (or even hiatus) during the MCA, and low data resolution, respectively (Texts S6, S7). 6.4. Ross Sea, Ross Ice Shelf and West Antarctica Most evidence from Victoria Land and the western Ross Sea points to a warm MCA (Fig. 7). An increase in temperature is documented by water isotopes in ice cores (sites 47 and 54) (Fig. S11). Diatom assemblages in marine sediment cores (sites 49 and 53) indicate warm water and reduced sea ice (Figs. 4, S11). Moraine dating suggests 9

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Fig. 6. Temperature trends during the Medieval Climate Anomaly in the Antarctic region. Site descriptions and climate proxy correlation panels in Supplement (texts and Figs. S2–S12). Zoom trends maps of the Antarctic Peninsula and Victoria Land in Figs. 5 and 7.

Dominion Range that are flanking the ice shelf (sites 56–59) (Figs. 4, 6, 7, S12). It must remain speculation if this area of cold MCA actually extends towards the South Pole (partly cold MCA in Site 36, Plateau Remote, Fig. S8) and even to the Ronne Filchner Ice Shelf (cold MCA in Site 31, Berkner Island, Fig. 4). Data from central West Antarctica is unfortunately scarce (Fig. 1). The only available site is the WAIS Divide ice core (Site 60) which shows a predominantly warm MCA (Figs. 6, S12).

before. In these cases, reported warm/cold MCA trends are relative to the subsequent Little Ice Age (LIA). MCA cooling occurred in the Ross Ice Shelf region, and probably in the Weddell Sea and on FilchnerRonne Ice Shelf. Cooling has been also proposed for the Crozet Archipelago which lies just north of the Antarctic Convergence (Fig. 6).

6.5. Trends summary

7.1. Ocean cycles

The palaeoclimatic mapping has identified several Antarctic regions with distinct MCA temperature response. A relatively warm MCA was found for the Subantarctic Islands south of the Antarctic Convergence, the Antarctic Peninsula, Victoria Land and central West Antarctica (Figs. 5–7). A somewhat noisier MCA warm signal was detected for the majority of East Antarctica. In some cases, the warm phase started several centuries before the MCA and reaches back to 500 CE and even

The MCA warming identified on the western side of the Antarctic Peninsula occurred during a time when the ENSO according to most reconstructions was El Niño-rich (Conroy et al., 2010; Conroy et al., 2008; Henke et al., 2017; Moy et al., 2002; Rustic et al., 2015; Yan et al., 2011) (Figs. 8, S1). A similar relationship is found in modern times, whereby El Niño-dominated conditions typically lead to rising temperatures in the Bellingshausen Sea (Markle et al., 2012;

7. Potential climate drivers of observed MCA spatial and temporal temperature patterns

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Fig. 7. Temperature trends during the Medieval Climate Anomaly in Victoria Land and the Ross Ice Shelf region. Site descriptions and climate proxy correlation panels in Supplement (texts S9, S10; Figs. S11, S12).

during El Niño-dominated times. Snowfall (surface mass balance) has been reduced during the MCA at the Weddell Sea coast (Thomas et al., 2017: their fig. 7b) which may be related to a weakening of the Ferrell cell as well as changes in the jet stream which typically occur in association with El Niño events in modern times (Yuan, 2004). A similar ENSO dipole exists in the Ross Sea area where El Niño today commonly results in warming of the outer Ross Sea and cooling of the Ross Ice Shelf region (Bertler et al., 2004; Bertler et al., 2018; Bromwich et al., 1993; Markle et al., 2012; Pope et al., 2017). This Ross Sea dipole seems to have been also active during the MCA, as evidenced by MCA warming of the western Ross Sea and MCA cooling in the ice cores around the Ross Sea Ice Shelf (Figs. 6, 9). It is unclear if the temperature variations suggested for the past

Stammerjohn et al., 2008; Yuan, 2004). The MCA warming may have been further intensified by an elevated SAM (Abram et al., 2014; Goodwin et al., 2014; Huang et al., 2010) that in modern times usually results in a temperature rise on the Antarctic Peninsula (Doddridge and Marshall, 2017; Ekaykin et al., 2014; Gillett et al., 2006; Kwok and Comiso, 2002; Schneider et al., 2012) and a drop in air temperature over most of East Antarctica (Kwok and Comiso, 2002) (Fig. 8). The MCA cooling observed in the Weddell Sea and on the FilchnerRonne Ice Shelf matches well with the ENSO Antarctic Dipole Pattern that today usually yields opposite temperature trends for the western and eastern sea regions of the Antarctic Peninsula (Yuan, 2004) (Fig. 9). Mulvaney et al. (2012) demonstrated that the dipole also operated at millennial time scales in which Weddell Sea cooling generally occurred 11

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Fig. 8. Reconstructions of key drivers of natural climate variability. Southern Annular Mode, SAM, 70 year loess filter (Abram et al., 2014); El Niño-Southern Oscillation, ENSO (Conroy et al., 2008); Interdecadal Pacific Oscillation, IPO, piece-wise linear fit (Vance et al., 2015); Pacific Decadal Oscillation, PDO (MacDonald and Case, 2005); Atlantic Multidecadal Oscillation, AMO (Mann et al., 2009); solar activity changes (Steinhilber et al., 2012); volcanic eruptions (Sigl et al., 2015).

Fig. 9. Inverse MCA temperature trends in the Antarctic Peninsula (AP) - Weddell Sea and Ross Sea regions compared to ENSO and SAM reconstructions. Proposed MCA dipoles are inspired by modern ENSO-driven temperature dipole trends. Proxy series: Southern Annular Mode, SAM, 70 year loess filter (Abram et al., 2014); El Niño-Southern Oscillation, ENSO (Conroy et al., 2008); site 18: JPC38 (Barbara et al., 2016); site 31: Berkner Island (Mulvaney et al., 2002); site 49: Woods Bay (Mezgec et al., 2017); site 56: Taylor Dome (Steig et al., 1998; Steig et al., 2000). 12

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stations (Suparta et al., 2010; Volobuev, 2014; Voskresenskiy and Chukanin, 1981). On multi-centennial time-scales many Antarctic palaeoclimatic records appear to be pulsed by the solar Suess/de Vries cycle which has a typical period in the range of 180–230 years. The cycle was found in several temperature and productivity proxy records of the Antarctic Peninsula, namely sites 9, 11 and 25 (Bárcena et al., 1998; Domack and Mayewski, 1999; Khim et al., 2002; Leventer et al., 1996) (Fig. 2). Suess/de Vries frequencies have been also identified in wind and temperature proxies in East Antarctic ice cores (Delmonte et al., 2005; Lüdecke et al., 2016; Zhao and Feng, 2015), off Adélie Land (Crosta et al., 2007) and Southern Hemisphere westerly airflow, closely related to SAM (Turney et al., 2016). On even longer time scales, millennial-scale cycles of the solar Eddy type with periods of 800–1200 years (Abreu et al., 2010) have been reported in Antarctic ice cores (Masson-Delmotte et al., 2004; Masson et al., 2000; Zhao and Feng, 2015) and marine Antarctic and Subantarctic sediments (Crosta et al., 2007; Nielsen et al., 2004). Antarctic snowfall, wind strength and air masses all appear to be influenced by solar activity (Bertler et al., 2005; Frezzotti et al., 2013; Mayewski et al., 2005). A short-lived cooling episode during the earliest MCA on Signy Island (Site 8) coincides with the solar Oort Minimum (1010–1050 CE) (Fig. S3). The penguin population of Prydz Bay over the past 1200 years appears to have been controlled by solar activity, most likely through a food-chain mechanism influencing the intensity of phytoplankton productivity and the abundance of krill (Gao et al., 2019).

1000 years in the Crozet Archipelago are robust, as nutrient input from elephant seals and wandering albatrosses may have obscured the climate signal (Ooms et al., 2011) (Site 2, see text S2 in Supplement for full discussion). The Crozet site is located close to the path of the Agulhas Return Current (Pollard et al., 2007). Notably, an MCA with cold SST has been reported from marine core GeoB 18308 (African Site 18 in Lüning et al., 2017) over the Agulhas Bank in coastal southern South Africa. Hahn et al. (2017) interpreted this to be a result of a strengthened and more southerly South Indian Ocean anticyclone which increased the Easterlies, Algulhas Current and upwelling activity in the Agulhas area during the MCA. An intensification of the Agulhas Return Current during the MCA may have brought cold upwelling water all the way to Crozet, although the interjacent SubAntarctic Front may have shielded Crozet from the Agulhas effects. 7.2. Solar forcing Ocean cycles such as ENSO, SAM and others control most of the climate variability in the Antarctic region, on time scales ranging from yearly to multi-centennial (Barbara et al., 2016; Bentley et al., 2009; Christ et al., 2015; Costa et al., 2007; Hall et al., 2010b; Jomelli et al., 2017; Mayewski et al., 2013; Shevenell et al., 2011; Shevenell and Kennett, 2002). The ultimate drivers of the ocean cycles, however, are still not fully understood. Besides an autocyclical element, external forcings are likely involved. For the industrial era, the SAM is thought to be influenced by anthropogenic changes in stratospheric ozone and greenhouse gases (Arblaster and Meehl, 2006). Another important external forcing candidate are solar activity changes. Visual comparison of ENSO, SAM and solar activity reconstructions shows similarities in the development of these parameters over the past 1500 years (Fig. 8). Whilst MCA and the last 100 years are characterized by high values, the Little Ice Age period 1400–1700 CE is mostly associated with low values. Studies have found a significant correlation between SAM and solar activity changes, when effects associated with the Quasi-Biennial Oscillation (QBO) are accounted for (Arblaster and Meehl, 2006; Haigh and Roscoe, 2006; Kuroda and Kodera, 2005; Roy and Haigh, 2011). The QBO is a quasiperiodic oscillation with a mean period of about 2.5 years which describes the reversal of wind directions in the tropical stratosphere from easterlies to westerlies. The solar influence on SAM appears to be triggered by changes in the ultraviolet radiation (UV) which lead to ozone anomalies in the polar lower stratosphere (Kuroda and Shibata, 2006; Mayewski et al., 2017) that are then passed down into the troposphere in form of a “top-down” mechanism (Petrick et al., 2012). The strength of the troposphere-stratosphere coupling is also thought to be modulated by solar activity (Kuroda et al., 2007). According to Petrick et al. (2012), positive SAM like patterns in the surface pressure and associated wind anomalies occur typically during solar maximum conditions. Likewise, several studies suggest a solar influence on ENSO for time scales ranging from annual to multi-centennial (Hassan et al., 2016; Mehta and Lau, 1997; Nuzhdina, 2002; Salas et al., 2016; Yan et al., 2011). Other studies suggest that the solar forcing of climate is modulated by ENSO (Emile-Geay et al., 2007; Ruzmaikin, 1999). The link between solar and ocean cycle variability is characterized by nonlinear dynamics which complicates identification of the solar signal. The solar impact on Antarctic climate is likely to be indirect and linked to a teleconnection in atmospheric circulation that forces complex feedback between the tropical Pacific and Antarctica (Frezzotti et al., 2013). Spectral analysis of Antarctic climate records has revealed characteristic cyclicities that correspond to well-known solar activity cycles. Schwabe cycles with a period of 11 years have been identified in marine sediments of the Adélie Drift at the East Antarctic Margin (Costa et al., 2007), Antarctic sea ice (Curran et al., 2003) as well as in modern temperature and water vapor measurements at various Antarctic

7.3. Volcanism The reconstructions of global volcanic forcing (Sigl et al., 2015) and global volcanic aerosol optical depth (Crowley and Unterman, 2013) suggest low volcanic activity during the early part of the MCA (950–1100 CE), and increased volcanic activity in the second half (1100–1350 CE), followed by low volcanic activity (1350–1600 CE) (Fig. 8). Comparison with Antarctic temperature proxy records (Figs. S2–S12) does not reveal a climate signal in the MCA and early LIA climate data that would correspond to this global volcanic activity pattern. A differentiation into Southern Hemisphere, Northern Hemisphere and tropical eruptions (Sigl et al., 2015) does again not find its representation in the Antarctic MCA temperature development. It is therefore assumed, that changes in volcanic activity have not played a significant role for the MCA in Antarctica (see also text S1h in supplement). This corresponds with the findings of Stenni et al. (2017) who failed to find a consistent Antarctic temperature response to large volcanic eruptions. 8. Regional and global context Stenni et al. (2017) published temperature reconstructions of the past 2000 years that are differentiated for seven Antarctic regions. The reconstructions are based on stacked composites of δ18O water isotopes from ice cores which for the MCA correspond to a similar set of cores as used in our analysis. Stenni et al. (2017) describe MCA warming for the East Antarctic Plateau and Victoria Land Coast, which matches our findings. Furthermore, their analysis confirmed the cool nature of the MCA for the Weddell Sea Coast and a mostly warm MCA on the West Antarctic Ice Sheet, based on single ice cores of Berkner Island (Site 31) and WAIS (Site 60), respectively. The MCA temperature development proposed by Stenni et al. (2017) for the Antarctic Peninsula appears less representative because it is only based on one ice core (James Ross Island, Site 21) that currently undergoes age model revisions. In addition, Site 21 appears to be located at the central dividing line of the Antarctic Dipole which separates a warm MCA on the western side from a cold MCA on the eastern side of the Antarctic Peninsula. Here, the additional non-ice core data from sites 9–30 allow to map the MCA in more detail than just based on ice cores. Another difference in our analysis compared to Stenni et al. (2017) is our delineation of a Ross Ice 13

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several palaeoclimatic patterns have been identified. 1) MCA warming was found for the Subantarctic Islands south of the Antarctic Convergence, the Antarctic Peninsula, Victoria Land and central West Antarctica. 2) A somewhat noisier MCA warming signal was detected for the majority of East Antarctica. 3) MCA cooling occurred in the Ross Ice Shelf region, and probably in the Weddell Sea and on FilchnerRonne Ice Shelf. 4) Spatial distribution of MCA cooling and warming follows modern dipole patterns. Future studies will have to further refine and test these patterns, in particular for data-poor areas outside the Antarctic Peninsula. In particular marine cores are needed to complement the ice core data (Fig. 1). Main drivers of the multi-centennial scale climate variability appear to be the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO) which are linked to solar activity changes by nonlinear dynamics. The MCA forms the final part of a long warm phase that dominated the first millennium CE and ended 1250 CE with the onset of significant cooling in the transition to the Little Ice Age (LIA). Overall timing of the MCA and LIA in Antarctica matches the climate development of the Northern Hemisphere. Natural variability still overwhelms the forced response in the recent Antarctic climate development, and models appear to not fully represent this natural variability. Multiple evidence points to a significant solar influence on Antarctic climate which may be worth testing in future model scenarios in greater detail.

Shelf sector which we interpret to be characterized by a cold MCA based on four ice cores (sites 56–59; Fig. 7). The Stenni study documents a significant cooling in the integrated continent-wide Antarctic temperature curve which occurs around 1250 CE and marks the transition to generally cold Little Ice Age which lasts here until 1950 CE. The LIA cooling in Stenni et al. (2017) is even more pronounced than in the previous version of the Antarctic temperature reconstruction by PAGES 2k Consortium (2013) which also only uses ice cores. In both reconstructions, the phase 0 to1000 CE is at least as warm as the MCA itself, which is also reflected in many of the non-ice core datasets (Figs. S2–S12). Notably, solar activity was also high during this entire phase, except a less active episode around 700 CE (Fig. 8). Neukom and Gergis (2012) and Neukom et al. (2014) compiled temperature reconstructions for the Southern Hemisphere in which Antarctica is represented exclusively by ice cores. Just four of the ice cores reach back to the MCA (Berkner Island, Dronning Maud, Law Dome, Siple Dome; sites 31, 32, 46, 58). Half of these lie in the rather small MCA cold areas of the Weddell Sea and Ross Ice Shelf (Fig. 6). The Antarctic MCA reconstruction in these two studies therefore cannot be considered representative in terms of an area-weighted continent-wide average. The question of a globally coherent warm phase during medieval times therefore remains open and certainly requires higher resolution data from Southern Hemisphere locations and a better knowledge of local temperature dipoles. Another Antarctic temperature reconstruction based on ice cores has been published by Goosse et al. (2012). Three out of the seven cores are located in the small Antarctic sectors with a cold MCA (sites 31, 56, 58), which again distorts the continent-wide MCA average of the reconstruction (Fig. 6). Mann et al. (2008) included various ice cores into their global temperature reconstruction, none of which reached back to the MCA. Data of longer cores were cut and only commenced after the MCA. The often-cited temperature reconstructions by Moberg et al. (2005), Hegerl et al. (2007) and Ljungqvist et al. (2012) only cover the Northern Hemisphere. Climate models still fail to replicate the continent-scale absence of 20th century warming in Antarctica (Abram et al., 2016; Goosse, 2017; Jones et al., 2016; Stenni et al., 2017). Similar discrepancies between simulated and reconstructed temperature development exist on a Holocene scale (Ackerley et al., 2017). A previous attempt by Goosse et al. (2012) to explain the Antarctic long term cooling trend 0–1950 CE in simulations by volcanic forcing is not compatible with the latest volcanic forcing reconstructions (Sigl et al., 2015) (Fig. 8). Recent research found a negative greenhouse effect for CO2 over the highest elevations of central Antarctica (Schmithüsen et al., 2015). Nevertheless, Smith et al. (2018) consider it unlikely that this plays a role in the recently observed East Antarctic cooling. Natural variability still overwhelms the forced response in the recent Antarctic climate development, but the models appear to not fully represent this natural variability or may overestimate the magnitude of the forced response (Jones et al., 2016). Given the strong solar influence on pre-industrial Antarctic climate, solar forcing may actually play a stronger role in modern Antarctic climate than previously thought, which may be worth testing in respective model scenarios.

Acknowledgements We wish to thank all scientists whose case studies form the basis of this palaeoclimate mapping synthesis. We are grateful for provision of tabulated data and valuable discussions to Wenshen Xiao, Robert Mulvaney, Rebecca Minzoni, Stephanie Strother, Loïc Barbara, Patrick Monien, Willem van der Bilt, Svante Björck, Rolf Zale, Dmitry Divine, Sonja Berg, Nancy Bertler, Barbara Stenni, James White, Tyler Jones, Jean Jouzel, Valérie Masson-Delmotte, Tas van Ommen, Alexey Ekaykin, Hugues Goosse, Vincent Jomelli, Stephen McIntyre, Françoise Vimeux, Ronald Kwok, Boo-Keun Khim, Damien Irving, Jessica Conroy, Paul Vaughan, Liz Thomas, Xavier Crosta, Jonathan Stelling, Yuesong Gao and Ian Goodwin. A large amount of data was sourced through the PANGAEA online data base and the NOAA National Centers for Environmental Information (NCEI, formerly NCDC), invaluable services which are greatly acknowledged. A big thank you goes to Frank Bosse for calculating the MCA trend statistics. We are indebted to Jurgis Klaudius and Lloyd's Register for providing the database and correlation software IC™ for this project. This review forms part of the Medieval Climate Anomaly Mapping Project which has been kindly supported by crowdfunding. We are particularly grateful to Jens Kröger for helping to jump-start the project. Kind support was also received by Hans Fischer, Christiane & Michael Grunenberg, Arnd Externbrink, Hans-Joachim Dammschneider, Rainer Frank Elsaesser, Uli Weber, Jochen Zimmermann, and many others. Note that this study is fully unrelated to the first author's employment in the hydrocarbon sector and was neither commissioned nor funded by the energy industry. SL undertook this study outside office hours as a private person, trained geoscientist, and former full-time academic. We are grateful to two anonymous reviewers who greatly helped to improve this manuscript.

9. Conclusions Appendix A. Supplementary data The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 CE. It is still being debated whether the MCA also occurred in the Southern Hemisphere. Here we mapped the MCA across the Antarctic region based on the analysis of published palaeotemperature proxy data from 60 sites in the Antarctic region. We are augmenting the conventionally used ice core data by adding temperature proxy records from marine and terrestrial sediment cores as well as radiocarbon ages of glacier moraines and elephant seal colonies. Although variable,

Supplementary data to this article can be found online at https:// doi.org/10.1016/j.palaeo.2019.109251. References Abram, N.J., Mulvaney, R., Wolff, E.W., Triest, J., Kipfstuhl, S., Trusel, L.D., Vimeux, F., Fleet, L., Arrowsmith, C., 2013. Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century. Nat. Geosci. 6 (5), 404–411.

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Late Holocene glacial advance and ice shelf growth in Barilari Bay, Graham Land, west Antarctic Peninsula. GSA Bull. 127 (1-2), 297–315. Chylek, P., Folland, C.K., Lesins, G., Dubey, M.K., 2010. Twentieth century bipolar seesaw of the Arctic and Antarctic surface air temperatures. Geophys. Res. Lett. 37, 1–4. Clapperton, C.M., Sugden, D.E., Birnie, J., Wilson, M.J., 1989. Late-glacial and Holocene glacier fluctuations and environmental change on South Georgia, Southern Ocean. Quat. Res. 31 (2), 210–228. Clem, K.R., Renwick, J.A., McGregor, J., 2018. Autumn cooling of Western East Antarctica linked to the Tropical Pacific. J. Geophys. Res. Atmos. 123 (1), 89–107. Conroy, J.L., Overpeck, J.T., Cole, J.E., Shanahan, T.M., Steinitz-Kannan, M., 2008. Holocene changes in eastern tropical Pacific climate inferred from a Galápagos lake sediment record. Quat. Sci. Rev. 27 (11), 1166–1180. Conroy, J.L., Overpeck, J.T., Cole, J.E., 2010. El Niño/Southern Oscillation and changes in the zonal gradient of tropical Pacific sea surface temperature over the last 1.2 ka. PAGES News 18 (1), 32–36. Costa, E., Dunbar, R.B., Kryc, K.A., Mucciarone, D.A., Brachfeld, S., Roark, E.B., Manley, P.L., Murray, R.W., Leventer, A., 2007. Solar Forcing and El Niño-Southern Oscillation (ENSO) Influences on Productivity Cycles Interpreted From a LateHolocene High-Resolution Marine Sediment Record, Adélie Drift, East Antarctic Margin: U.S. Geological Survey. (Open-File Report 2007-1047, Short Research Paper 036). Crosta, X., Debret, M., Denis, D., Courty, M.A., Ther, O., 2007. Holocene long- and shortterm climate changes off Adélie Land, East Antarctica. Geochem. Geophys. Geosyst. 8 (11), 1–15. Crowley, T.J., Lowery, T.S., 2000. How warm was the Medieval Warm Period? AMBIO J. Hum. Environ. 29 (1), 51–54. Crowley, T.J., Unterman, M.B., 2013. Technical details concerning development of a 1200 yr proxy index for global volcanism. Earth Syst. Sci. Data 5 (1), 187–197. Curran, M.A.J., van Ommen, T.D., Morgan, V.I., Phillips, K.L., Palmer, A.S., 2003. Ice core evidence for Antarctic sea ice decline since the 1950s. Science 302 (5648), 1203–1206. Dahl-Jensen, D., Morgan, V.I., Elcheikh, A., 1999. Monte Carlo inverse modelling of the Law Dome (Antarctica) temperature profile. Ann. Glaciol. 29 (1), 145–150. Dash, M.K., Pandey, P.C., Vyas, N.K., Turner, J., 2013. Variability in the ENSO-induced southern hemispheric circulation and Antarctic sea ice extent. Int. J. Climatol. 33 (3), 778–783. Davies, B.J., Golledge, N.R., Glasser, N.F., Carrivick, J.L., Ligtenberg, S.R.M., Barrand, N.E., van den Broeke, M.R., Hambrey, M.J., Smellie, J.L., 2014. Modelled glacier response to centennial temperature and precipitation trends on the Antarctic Peninsula. Nat. Clim. Chang. 4, 993. Delmonte, B., Petit, J.R., Krinner, G., Maggi, V., Jouzel, J., Udisti, R., 2005. Ice core evidence for secular variability and 200-year dipolar oscillations in atmospheric circulation over East Antarctica during the Holocene. Clim. Dyn. 24 (6), 641–654. Divine, D.V., Koç, N., Isaksson, E., Nielsen, S., Crosta, X., Godtliebsen, F., 2010. Holocene Antarctic climate variability from ice and marine sediment cores: insights on ocean–atmosphere interaction. Quat. Sci. Rev. 29 (1), 303–312. Doddridge, E.W., Marshall, J., 2017. Modulation of the seasonal cycle of Antarctic Sea ice extent related to the Southern Annular Mode. Geophys. Res. Lett. 44 (19), 9761–9768. Domack, E.W., Mayewski, P.A., 1999. Bi-polar ocean linkages: evidence from lateHolocene Antarctic marine and Greenland ice-core records. The Holocene 9 (2), 247–251. Domack, E.W., Ishman, S.E., Stein, A.B., McClennen, C.E., Jull, A.J.T., 1995. Late Holocene advance of the Müller Ice Shelf, Antarctic Peninsula: sedimentological, geochemical and palaeontological evidence. Antarct. Sci. 7 (2), 159–170. Ekaykin, A.A., Kozachek, A.V., Lipenkov, V.Y., Shibaev, Y.A., 2014. Multiple climate shifts in the Southern Hemisphere over the past three centuries based on central Antarctic snow pits and core studies. Ann. Glaciol. 55 (66), 259–266. Emile-Geay, J., Cane, M., Seager, R., Kaplan, A., Almasi, P., 2007. El Niño as a mediator of the solar influence on climate. Paleoceanography 22 (3) (p. n/a-n/a). Engel, Z., Láska, K., Nyvlt, D., Stachon, Z., 2018. Surface mass balance of small glaciers on James Ross Island, north-eastern Antarctic Peninsula, during 2009–2015. J. Glaciol. 64 (245), 349–361. Esper, J., Frank, D., 2009. The IPCC on a heterogeneous Medieval Warm Period. Clim. Chang. 94 (3), 267–273. Fan, T., Deser, C., Schneider, D.P., 2014. Recent Antarctic sea ice trends in the context of Southern Ocean surface climate variations since 1950. Geophys. Res. Lett. 41 (7), 2419–2426. Favier, V., Krinner, G., Amory, C., Gallée, H., Beaumet, J., Agosta, C., 2017. AntarcticaRegional Climate and Surface Mass Budget: Current Climate Change Reports. Fegyveresi, J.M., Alley, R.B., Fitzpatrick, J.J., Cuffey, K.M., McConnell, J.R., Voigt, D.E., Spencer, M.K., Stevens, N.T., 2016. Five millennia of surface temperatures and ice core bubble characteristics from the WAIS Divide deep core, West Antarctica. Paleoceanography 31 (3), 416–433. Fernandoy, F., Tetzner, D., Meyer, H., Gacitúa, G., Hoffmann, K., Falk, U., Lambert, F., MacDonell, S., 2018. New insights into the use of stable water isotopes at the northern Antarctic Peninsula as a tool for regional climate studies. Cryosphere 12, 1069–1090. Fogt, R.L., Goergens, C.A., Jones, J.M., Schneider, D.P., Nicolas, J.P., Bromwich, D.H., Dusselier, H.E., 2017. A twentieth century perspective on summer Antarctic pressure change and variability and contributions from tropical SSTs and ozone depletion. Geophys. Res. Lett. 44 (19), 9918–9927. Foster, L.C., Pearson, E.J., Juggins, S., Hodgson, D.A., Saunders, K.M., Verleyen, E., Roberts, S.J., 2016. Development of a regional glycerol dialkyl glycerol tetraether (GDGT)–temperature calibration for Antarctic and sub-Antarctic lakes. Earth Planet. Sci. Lett. 433, 370–379.

Abram, N.J., Mulvaney, R., Vimeux, F., Phipps, S.J., Turner, J., England, M.H., 2014. Evolution of the Southern Annular Mode during the past millennium. Nat. Clim. Chang. 4, 564. Abram, N.J., McGregor, H.V., Tierney, J.E., Evans, M.N., McKay, N.P., Kaufman, D.S., the, P. k. C, 2016. Early onset of industrial-era warming across the oceans and continents. Nature 536, 411. Abreu, J.A., Beer, J., Ferriz-Mas, A., 2010. Past and future solar activity from cosmogenic radionuclides. In: Cranmer, S.R., Hoeksema, J.T., Kohl, J.L. (Eds.), SOHO-23: Understanding a Peculiar Solar Minimum. ASP Conference Series, vol. 428. pp. 287–295. Ackerley, D., Reeves, J., Barr, C., Bostock, H., Fitzsimmons, K., Fletcher, M.S., Gouramanis, C., McGregor, H., Mooney, S., Phipps, S.J., Tibby, J., Tyler, J., 2017. Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the IndoPacific, Australasian and Southern Ocean regions. Clim. Past 13 (11), 1661–1684. Allen, C.S., Oakes-Fretwell, L., Anderson, J.B., Hodgson, D.A., 2010. A record of Holocene glacial and oceanographic variability in Neny Fjord, Antarctic Peninsula. The Holocene 20 (4), 551–564. Arblaster, J.M., Meehl, G.A., 2006. Contributions of external forcings to Southern Annular Mode trends. J. Clim. 19 (12), 2896–2905. Armour, K.C., Marshall, J., Scott, J.R., Donohoe, A., Newsom, E.R., 2016. Southern ocean warming delayed by circumpolar upwelling and equatorward transport. Nat. Geosci. 9, 549. Barbara, L., Crosta, X., Leventer, A., Schmidt, S., Etourneau, J., Domack, E., Massé, G., 2016. Environmental responses of the Northeast Antarctic Peninsula to the Holocene climate variability. Paleoceanography 31 (1), 131–147. Bárcena, M.A., Gersonde, R., Ledesma, S., Fabrés, J., Calafat, A.M., Canals, M., Sierro, F.J., Flores, J.A., 1998. Record of Holocene glacial oscillations in Bransfield Basin as revealed by siliceous microfossil assemblages. Antarct. Sci. 10 (3), 269–285. Barnard, A., Wellner, J.S., Anderson, J.B., 2014. Late Holocene climate change recorded in proxy records from a Bransfield Basin sediment core, Antarctic Peninsula. Polar Res. 33 (1), 17236. Baroni, C., Orombelli, G., 1994a. Abandoned penguin rookeries as Holocene paleoclimatic indicators in Antarctica. Geology 22 (1), 23–26. Baroni, C., Orombelli, G., 1994b. Holocene glacier variations in the Terra Nova Bay area (Victoria Land, Antarctica). Antarct. Sci. 6 (4), 497–505. Bentley, M.J., Hodgson, D.A., Smith, J.A., Cofaigh, C.Ó., Domack, E.W., Larter, R.D., Roberts, S.J., Brachfeld, S., Leventer, A., Hjort, C., Hillenbrand, C.-D., Evans, J., 2009. Mechanisms of Holocene palaeoenvironmental change in the Antarctic Peninsula region. The Holocene 19 (1), 51–69. Berg, S., Wagner, B., Cremer, H., Leng, M.J., Melles, M., 2010. Late Quaternary environmental and climate history of Rauer Group, East Antarctica. Palaeogeogr. Palaeoclimatol. Palaeoecol. 297 (1), 201–213. Bertler, N.A.N., Barrett, P.J., Mayewski, P.A., Fogt, R.L., Kreutz, K.J., Shulmeister, J., 2004. El Niño suppresses Antarctic warming. Geophys. Res. Lett. 31 (15) (p. n/a-n/a). Bertler, N.A.N., Mayewski, P.A., Sneed, S.B., Naish, T.R., Morgenstern, U., Barrett, P.J., 2005. Solar forcing recorded by aerosol concentrations in coastal. Ann. Glaciol. 41, 52–56. Bertler, N.A.N., Mayewski, P.A., Carter, L., 2011. Cold conditions in Antarctica during the Little Ice Age — implications for abrupt climate change mechanisms. Earth Planet. Sci. Lett. 308, 41–51. Bertler, N.A.N., Conway, H., Dahl-Jensen, D., Emanuelsson, D.B., Winstrup, M., Vallelonga, P.T., Lee, J.E., Brook, E.J., Severinghaus, J.P., Fudge, T.J., Keller, E.D., Baisden, W.T., Hindmarsh, R.C.A., Neff, P.D., Blunier, T., Edwards, R., Mayewski, P.A., Kipfstuhl, S., Buizert, C., Canessa, S., Dadic, R., Kjær, H.A., Kurbatov, A., Zhang, D., Waddington, E.D., Baccolo, G., Beers, T., Brightley, H.J., Carter, L., ClemensSewall, D., Ciobanu, V.G., Delmonte, B., Eling, L., Ellis, A.A., Ganesh, S., Golledge, N.R., Haines, S.A., Handley, M., Hawley, R.L., Hogan, C.M., Johnson, K.M., Korotkikh, E., Lowry, D.P., Mandeno, D., McKay, R.M., Menking, J.A., Naish, T.R., Noerling, C., Ollive, A., Orsi, A., Proemse, B.C., Pyne, A.R., Pyne, R.L., Renwick, J., Scherer, R.P., Semper, S., Simonsen, M., Sneed, S.B., Steig, E.J., Tuohy, A., Ulayottil Venugopal, A., Valero-Delgado, F., Venkatesh, J., Wang, F., Wang, S., Winski, D.A., Winton, V.H.L., Whiteford, A., Xiao, C., Yang, J., Zhang, X., 2018. The Ross Sea dipole - temperature, snow accumulation and sea ice variability in the Ross Sea Region, Antarctica, over the past 2,700 years. Clim. Past 14, 193–214. van der Bilt, W.G.M., Bakke, J., Werner, J.P., Paasche, Ø., Rosqvist, G., Vatle, S.S., 2017. Late Holocene glacier reconstruction reveals retreat behind present limits and twostage Little Ice Age on subantarctic South Georgia. J. Quat. Sci. 32 (6), 888–901. Björck, S., Håkansson, H., Zale, R., Karlén, W., Jönsson, B.L., 1991. A late Holocene lake sediment sequence from Livingston Island, South Shetland Islands, with palaeoclimatic implications. Antarct. Sci. 3 (1), 61–72. Bromwich, D.H., Carrasco, J.F., Liu, Z., Tzeng, R.-Y., 1993. Hemispheric atmospheric variations and oceanographic impacts associated with katabatic surges across the Ross ice shelf, Antarctica. J. Geophys. Res. Atmos. 98 (D7), 13045–13062. Bromwich, D.H., Nicolas, J.P., Monaghan, A.J., Lazzara, M.A., Keller, L.M., Weidner, G.A., Wilson, A.B., 2013. Central West Antarctica among the most rapidly warming regions on Earth. Nat. Geosci. 6, 139–145. Bukatov, A.E., Bukatov, A.A., Babii, M.V., 2016. Regional variability of Antarctic sea ice extent. Russ. Meteorol. Hydrol. 41 (6), 404–409. Bunde, A., Ludescher, J., Franzke, C.L.E., Büntgen, U., 2014. How significant is West Antarctic warming? Nat. Geosci. 7, 246. Casado, M., Landais, A., Picard, G., Münch, T., Laepple, T., Stenni, B., Dreossi, G., Ekaykin, A., Arnaud, L., Genthon, C., Touzeau, A., Masson-Delmotte, V., Jouzel, J., 2017. Archival processes of the water stable isotope signal in East Antarctic ice cores. Cryosphere Discuss. 2017, 1–36. Christ, A.J., Talaia-Murray, M., Elking, N., Domack, E.W., Leventer, A., Lavoie, C., Brachfeld, S., Yoo, K.-C., Gilbert, R., Jeong, S.-M., Petrushak, S., Wellner, J., 2015.

15

Palaeogeography, Palaeoclimatology, Palaeoecology 532 (2019) 109251

S. Lüning, et al.

273–285. Jomelli, V., Mokadem, F., Schimmelpfennig, I., Chapron, E., Rinterknecht, V., Favier, V., Verfaillie, D., Brunstein, D., Legentil, C., Michel, E., Swingedouw, D., Jaouen, A., Aumaitre, G., Bourlès, D.L., Keddadouche, K., 2017. Sub-Antarctic glacier extensions in the Kerguelen region (49°S, Indian Ocean) over the past 24,000 years constrained by 36Cl moraine dating. Quat. Sci. Rev. 162, 128–144. Jones, J.M., Gille, S.T., Goosse, H., Abram, N.J., Canziani, P.O., Charman, D.J., Clem, K.R., Crosta, X., de Lavergne, C., Eisenman, I., England, M.H., Fogt, R.L., Frankcombe, L.M., Marshall, G.J., Masson-Delmotte, V., Morrison, A.K., Orsi, A.J., Raphael, M.N., Renwick, J.A., Schneider, D.P., Simpkins, G.R., Steig, E.J., Stenni, B., Swingedouw, D., Vance, T.R., 2016. Assessing recent trends in high-latitude Southern Hemisphere surface climate. Nat. Clim. Chang. 6, 917. Khim, B.-K., Yoon, H.I., Kang, C.Y., Bahk, J.J., 2002. Unstable Climate Oscillations during the Late Holocene in the Eastern Bransfield Basin, Antarctic Peninsula. Quat. Res. 58 (3), 234–245. Kim, S., Yoo, K.-C., Lee, J.I., Khim, B.-K., Bak, Y.-S., Lee, M.K., Lee, J., Domack, E.W., Christ, A.J., Yoon, H.I., 2018. Holocene paleoceanography of Bigo Bay, west Antarctic Peninsula: connections between surface water productivity and nutrient utilization and its implication for surface-deep water mass exchange. Quat. Sci. Rev. 192, 59–70. Klein, F., Abram, N.J., Curran, M.A.J., Goosse, H., Goursaud, S., Masson-Delmotte, V., Moy, A., Neukom, R., Orsi, A., Sjolte, J., Steiger, N., Stenni, B., Werner, M., 2018. Assessing the robustness of Antarctic temperature reconstructions over the past two millennia using pseudoproxy and data assimilation experiments. Clim. Past Discuss. 2018 (p), 1–35. Kuroda, Y., Kodera, K., 2005. Solar cycle modulation of the Southern Annular Mode. Geophys. Res. Lett. 32 (13) (p. n/a-n/a). Kuroda, Y., Shibata, K., 2006. Simulation of solar-cycle modulation of the Southern Annular Mode using a chemistry-climate model. Geophys. Res. Lett. 33 (5) (p. n/an/a). Kuroda, Y., Deushi, M., Shibata, K., 2007. Role of solar activity in the troposphere-stratosphere coupling in the Southern Hemisphere winter. Geophys. Res. Lett. 34 (21) (p. n/a-n/a). Kusahara, K., Williams, G.D., Massom, R., Reid, P., Hasumi, H., 2017. Roles of wind stress and thermodynamic forcing in recent trends in Antarctic sea ice and Southern Ocean SST: an ocean-sea ice model study. Glob. Planet. Chang. 158 (Supplement C), 103–118. Kwok, R., Comiso, J.C., 2002. Spatial patterns of variability in Antarctic surface temperature: connections to the Southern Hemisphere Annular Mode and the Southern Oscillation. Geophys. Res. Lett. 29 (14), 50-51–50-54. Laepple, T., Münch, T., Casado, M., Hoerhold, M., Landais, A., Kipfstuhl, S., 2018. On the similarity and apparent cycles of isotopic variations inEast Antarctic snow pits. Cryosphere 12 (1), 169–187. Lamb, H.H., 1965. The early medieval warm epoch and its sequel. Palaeogeogr. Palaeoclimatol. Palaeoecol. 1, 13–37. Latif, M., Martin, T., Reintges, A., Park, W., 2017. Southern ocean decadal variability and predictability. Curr. Clim. Chang. Rep. 3 (3), 163–173. Leventer, A., Dunbar, R.B., DeMaster, D.J., 1993. Diatom evidence for Late Holocene climatic events in Granite Harbor, Antarctica. Paleoceanography 8 (3), 373–386. Leventer, A., Domack, E.W., Ishman, S.E., Brachfeld, S., McClennen, C.E., Manley, P., 1996. Productivity cycles of 200–300 years in the Antarctic Peninsula region: understanding linkages among the sun, atmosphere, oceans, sea ice, and biota. GSA Bull. 108 (12), 1626–1644. Li, X., Holland, D.M., Gerber, E.P., Yoo, C., 2014. Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice. Nature 505, 538. Liu, X., Sun, L., Xie, Z., Yin, X., Wang, Y., 2005. A 1300-year record of penguin populations at Ardley Island in the Antarctic, as deduced from the geochemical data in the ornithogenic lake sediments. Arct. Antarct. Alp. Res. 37 (4), 490–498. Ljungqvist, F.C., Krusic, P.J., Brattström, G., Sundqvist, H.S., 2012. Northern Hemisphere temperature patterns in the last 12 centuries. Clim. Past 8, 227–249. Lovell, A.M., Stokes, C.R., Jamieson, S.S.R., 2017. Sub-decadal variations in outlet glacier terminus positions in Victoria Land, Oates Land and George V Land, East Antarctica (1972–2013). Antarct. Sci. 29 (5), 468–483. Lu, Z., Rickaby, R.E.M., Kennedy, H., Kennedy, P., Pancost, R.D., Shaw, S., Lennie, A., Wellner, J., Anderson, J.B., 2012. An ikaite record of late Holocene climate at the Antarctic Peninsula. Earth Planet. Sci. Lett. 325–326 (0), 108–115. Lüdecke, H.J., Weiss, C.O., Zhao, X., Feng, X., 2016. Centennial cycles observed in temperature data from Antarctica to central Europe. Polarforschung 85 (2), 179–181. Ludescher, J., Bunde, A., Franzke, C.L.E., Schellnhuber, H.J., 2016. Long-term persistence enhances uncertainty about anthropogenic warming of Antarctica. Clim. Dyn. 46 (1), 263–271. Lüning, S., Gałka, M., Vahrenholt, F., 2017. Warming and cooling: the Medieval climate anomaly in Africa and Arabia. Paleoceanography 32 (11), 1219–1235. Lüning, S., Gałka, M., Danladi, I.B., Adagunodo, T.A., Vahrenholt, F., 2018. Hydroclimate in Africa during the Medieval climate anomaly. Palaeogeogr. Palaeoclimatol. Palaeoecol. 495, 309–322. Lüning, S., Gałka, M., Bamonte, F.P., Rodríguez, F.G., Vahrenholt, F., 2019a. The Medieval climate anomaly in South America. Quat. Int. 508, 70–87. Lüning, S., Gałka, M., García-Rodríguez, F., Vahrenholt, F., 2019b. The Medieval climate anomaly in Oceania. Environ. Rev. https://doi.org/10.1139/er-2019-0012. Luthi, S.M., 2001. Well Correlation, Geological Well Logs: Their Use in Reservoir Modeling. Springer Berlin Heidelberg, Berlin, Heidelberg, pp. 317–341. MacDonald, G.M., Case, R.A., 2005. Variations in the Pacific decadal oscillation over the past millennium. Geophys. Res. Lett. 32, 1–4. Mann, M.E., Zhang, Z., Hughes, M.K., Bradley, R.S., Miller, S.K., Rutherford, S., Ni, F., 2008. Proxy-based reconstructions of hemispheric and global surface temperature

Frezzotti, M., Scarchilli, C., Becagli, S., Proposito, M., Urbini, S., 2013. A synthesis of the Antarctic surface mass balance during the last 800 yr. Cryosphere 7 (1), 303–319. Fudge, T.J., Markle, B.R., Cuffey, K.M., Buizert, C., Taylor, K.C., Steig, E.J., Waddington, E.D., Conway, H., Koutnik, M., 2016. Variable relationship between accumulation and temperature in West Antarctica for the past 31,000 years. Geophys. Res. Lett. 43 (8), 3795–3803. Gao, Y., Yang, L., Yang, W., Wang, Y., Xie, Z., Sun, L., 2019. Dynamics of penguin population size and food availability at Prydz Bay, East Antarctica, during the last millennium: a solar control. Palaeogeogr. Palaeoclimatol. Palaeoecol. 516, 220–231. Gillett, N.P., Kell, T.D., Jones, P.D., 2006. Regional climate impacts of the Southern Annular Mode. Geophys. Res. Lett. 33 (23) (p. n/a-n/a). Goel, V., Brown, J., Matsuoka, K., 2017. Glaciological settings and recent mass balance of the Blåskimen Island in Dronning Maud Land, Antarctica. Cryosphere Discuss. 2017, 1–24. Goodwin, I.D., Browning, S., Lorrey, A.M., Mayewski, P.A., Phipps, S.J., Bertler, N.A.N., Edwards, R.P., Cohen, T.J., van Ommen, T., Curran, M., Barr, C., Stager, J.C., 2014. A reconstruction of extratropical Indo-Pacific sea-level pressure patterns during the Medieval Climate Anomaly. Clim. Dyn. 43 (5), 1197–1219. Goosse, H., 2017. Reconstructed and simulated temperature asymmetry between continents in both hemispheres over the last centuries. Clim. Dyn. 48 (5), 1483–1501. Goosse, H., Masson-Delmotte, V., Renssen, H., Delmotte, M., Fichefet, T., Morgan, V., van Ommen, T., Khim, B.K., Stenni, B., 2004. A Late Medieval Warm Period in the Southern Ocean as a delayed response to external forcing? Geophys. Res. Lett. 31 (6) (p. n/a-n/a). Goosse, H., Braida, M., Crosta, X., Mairesse, A., Masson-Delmotte, V., Mathiot, P., Neukom, R., Oerter, H., Philippon, G., Renssen, H., Stenni, B., van Ommen, T., Verleyen, E., 2012. Antarctic temperature changes during the last millennium: evaluation of simulations and reconstructions. Quat. Sci. Rev. 55 (Supplement C), 75–90. Govil, P., Mazumder, A., Asthana, R., Tiwari, A., Mishra, R., 2016. Holocene climate variability from the lake sediment core in Schirmacher Oasis region, East Antarctica: multiproxy approach. Quat. Int. 425, 453–463. Graf, W., Oerter, H., Reinwarth, O., Stichler, W., Wilhelms, F., Miller, H., Mulvaney, R., 2002. Stable-isotope records fromDronningMaud Land, Antarctica. Ann. Glaciol. 35, 195–201. Graf, W., Oerter, H., Mulvaney, R., 2006. Delta18O Records From Berkner Island and Dronning Maud Land, Antarctica: Forum for Research Into Ice Shelf Processes (FRISP). Report. 14. pp. 46–50. Grove, J.M., Switsur, R., 1994. Glacial geological evidence for the Medieval Warm Period. Clim. Chang. 26, 143–169. Guglielmin, M., Convey, P., Malfasi, F., Cannone, N., 2016. Glacial fluctuations since the ‘Medieval Warm Period’ at Rothera Point (western Antarctic Peninsula). The Holocene 26 (1), 154–158. Hahn, A., Schefuß, E., Andó, S., Cawthraw, H.C., Frenzel, P., Kugel, M., Meschner, S., Mollenhauer, G., Zabel, M., 2017. Southern Hemisphere anticyclonic circulation drives oceanic and climatic conditions in late Holocene southernmost Africa. Clim. Past 13, 649–665. Haigh, J.D., Roscoe, H.K., 2006. Solar influences on polar modes of variability. Meteorol. Z. 15 (3), 371–378. Hall, B.L., 2007. Late-Holocene advance of the Collins Ice Cap, King George Island, South Shetland Islands. The Holocene 17 (8), 1253–1258. Hall, B.L., Denton, G.H., 2002. Holocene history of the Wilson Piedmont Glacier along the southern Scott Coast, Antarctica. The Holocene 12 (5), 619–627. Hall, B.L., Hoelzel, A.R., Baroni, C., Denton, G.H., Le Boeuf, B.J., Overturf, B., Töpf, A.L., 2006. Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea. Proc. Natl. Acad. Sci. 103 (27), 10213–10217. Hall, B.L., Henderson, G.M., Baroni, C., Kellogg, T.B., 2010a. Constant Holocene Southern-Ocean 14C reservoir ages and ice-shelf flow rates. Earth Planet. Sci. Lett. 296 (1), 115–123. Hall, B.L., Koffman, T., Denton, G.H., 2010b. Reduced ice extent on the western Antarctic Peninsula at 700–970 cal. yr B.P. Geology 38 (7), 635–638. Hass, H.C., Kuhn, G., Monien, P., Brumsack, H.-J., Forwick, M., 2010. Climate fluctuations during the past two millennia as recorded in sediments from Maxwell Bay, South Shetland Islands, West Antarctica: Geological Society, London. Spec. Publ. 344 (1), 243–260. Hassan, D., Iqbal, A., Ahmad Hassan, S., Abbas, S., Ansari, M.R.K., 2016. Sunspots and ENSO relationship using Markov method. J. Atmos. Sol. Terr. Phys. 137 (Supplement C), 53–57. Hegerl, G.C., Crowley, T.J., Allen, M., Hyde, W.T., Pollack, H.N., Smerdon, J., Zorita, E., 2007. Detection of human influence on a new, validated 1500-year temperature reconstruction. J. Clim. 20 (4), 650–666. Hemer, M.A., Harris, P.T., 2003. Sediment core from beneath the Amery Ice Shelf, East Antarctica, suggests mid-Holocene ice-shelf retreat. Geology 31 (2), 127–130. Henke, L.M.K., Lambert, F.H., Charman, D.J., 2017. Was the Little Ice Age more or less El Niño-like than the Medieval Climate Anomaly? Evidence from hydrological and temperature proxy data. Clim. Past 13 (3), 267–301. Hodgson, D.A., Convey, P., 2005. A 7000-year record of oribatid mite communities on a maritime-Antarctic Island: responses to climate change. Arct. Antarct. Alp. Res. 37 (2), 239–245. Horiuchi, K., Uchida, T., Sakamoto, Y., Ohta, A., Matsuzaki, H., Shibata, Y., Motoyama, H., 2008. Ice core record of 10Be over the past millennium from Dome Fuji, Antarctica: a new proxy record of past solar activity and a powerful tool for stratigraphic dating. Quat. Geochronol. 3 (3), 253–261. Huang, J., Wang, S., Gong, D., Zhou, T., Wen, X., Zhang, Z., Zhu, J., 2010. Atmospheric oscillations over the last millennium. Chin. Sci. Bull. 55 (22), 2469–2472. Huang, T., Sun, L., Wang, Y., Kong, D., 2011. Late Holocene Adélie penguin population dynamics at Zolotov Island, Vestfold Hills, Antarctica. J. Paleolimnol. 45 (2),

16

Palaeogeography, Palaeoclimatology, Palaeoecology 532 (2019) 109251

S. Lüning, et al.

317–320. Noon, P.E., Leng, M.J., Jones, V.J., 2003. Oxygen-isotope (δ18O) evidence of Holocene hydrological changes at Signy Island, maritime Antarctica. The Holocene 13 (2), 251–263. Nuzhdina, M.A., 2002. Connection between ENSO phenomena and solar and geomagnetic activity. Nat. Hazards Earth Syst. Sci. 2, 83–89. O'Donnell, R., Lewis, N., McIntyre, S., Condon, J., 2011. Improved methods for PCA-based reconstructions: case study using the Steig et al. (2009) antarctic temperature reconstruction. J. Clim. 24 (8), 2099–2115. Oliva, M., Navarro, F., Hrbáček, F., Hernández, A., Nývlt, D., Pereira, P., Ruiz-Fernández, J., Trigo, R., 2017. Recent regional climate cooling on the Antarctic Peninsula and associated impacts on the cryosphere. Sci. Total Environ. 580 (Supplement C), 210–223. Ooms, M., van de Vijver, B., Temmerman, S., Beyens, L., 2011. A Holocene palaeoenviromental study of a sediment core from Ile de la Possession, Iles Crozet, subAntarctica. Antarct. Sci. 23 (5), 431–441. Oppedal, L.T., Bakke, J., Paasche, Ø., Werner, J.P., van der Bilt, W.G.M., 2018. Cirque glacier on South Georgia shows centennial variability over the last 7000 years. Front. Earth Sci. 6 (2). PAGES 2k Consortium, 2013. Continental-scale temperature variability during the past two millennia. Nat. Geosci. 6 (5), 339–346. PAGES 2k Consortium, 2017. A global multiproxy database for temperature reconstructions of the Common Era. In: Scientific Data. v. 4. https://www.ncdc.noaa.gov/ paleo-search/study/21171. Petrick, C., Matthes, K., Dobslaw, H., Thomas, M., 2012. Impact of the solar cycle and the QBO on the atmosphere and the ocean. J. Geophys. Res. Atmos. 117 (D17) (p. n/an/a). Philippe, M., Tison, J.L., Fjøsne, K., Hubbard, B., Kjær, H.A., Lenaerts, J.T.M., Drews, R., Sheldon, S.G., De Bondt, K., Claeys, P., Pattyn, F., 2016. Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica. Cryosphere 10 (5), 2501–2516. Plummer, C.T., Curran, M.A.J., van Ommen, T.D., Rasmussen, S.O., Moy, A.D., Vance, T.R., Clausen, H.B., Vinther, B.M., Mayewski, P.A., 2012. An independently dated 2000-yr volcanic record from Law Dome, East Antarctica, including a new perspective on the dating of the 1450s CE eruption of Kuwae, Vanuatu. Clim. Past 8 (6), 1929–1940. Pollard, R.T., Venables, H.J., Read, J.F., Allen, J.T., 2007. Large-scale circulation around the Crozet Plateau controls an annual phytoplankton bloom in the Crozet Basin. Deep-Sea Res. II Top. Stud. Oceanogr. 54 (18), 1915–1929. Pope, J.O., Holland, P.R., Orr, A., Marshall, G.J., Phillips, T., 2017. The impacts of El Niño on the observed sea ice budget of West Antarctica. Geophys. Res. Lett. 44 (12), 6200–6208. Ramesh, K.J., Soni, V.K., 2018. Perspectives of Antarctic weather monitoring and research efforts. Polar Sci. 18, 183–188. https://doi.org/10.1016/j.polar.2018.04.005. Roberts, D., Ommen, T.D.v., McMinn, A., Morgan, V., Roberts, J.L., 2001. Late-Holocene East Antarctic climate trends from ice-core and lake-sediment proxies. The Holocene 11 (1), 117–120. Roberts, S.J., Monien, P., Foster, L.C., Loftfield, J., Hocking, E.P., Schnetger, B., Pearson, E.J., Juggins, S., Fretwell, P., Ireland, L., Ochyra, R., Haworth, A.R., Allen, C.S., Moreton, S.G., Davies, S.J., Brumsack, H.-J., Bentley, M.J., Hodgson, D.A., 2017. Past penguin colony responses to explosive volcanism on the Antarctic Peninsula. Nat. Commun. 8, 14914. Roy, I., Haigh, J.D., 2011. The influence of solar variability and the quasi-biennial oscillation on lower atmospheric temperatures and sea level pressure. Atmos. Chem. Phys. 11 (22), 11679–11687. Rustic, G.T., Koutavas, A., Marchitto, T.M., Linsley, B.K., 2015. Dynamical excitation of the tropical Pacific Ocean and ENSO variability by Little Ice Age cooling. Science 350 (6267), 1537–1541. Ruzmaikin, A., 1999. Can El Nińo amplify the solar forcing of climate? Geophys. Res. Lett. 26 (15), 2255–2258. Salas, I., Herrera, C., Luque, J.A., Delgado, J., Urrutia, J., Jordan, T., 2016. Recent climatic events controlling the hydrological and the aquifer dynamics at arid areas: the case of Huasco River watershed, northern Chile. Sci. Total Environ. 571 (Supplement C), 178–194. Sallée, J.-B., 2018. Southern ocean warming. Oceanography 31 (2), 52–62. Schmithüsen, H., Notholt, J., König-Langlo, G., Lemke, P., Jung, T., 2015. How increasing CO2 leads to an increased negative greenhouse effect in Antarctica. Geophys. Res. Lett. 42 (23), 10,422–410,428. Schneider, D.P., Steig, E.J., van Ommen, T.D., Dixon, D.A., Mayewski, P.A., Jones, J.M., Bitz, C.M., 2006. Antarctic temperatures over the past two centuries from ice cores. Geophys. Res. Lett. 33 (16) (p. n/a-n/a). Schneider, D.P., Okumura, Y., Deser, C., 2012. Observed Antarctic interannual climate variability and tropical linkages. J. Clim. 25 (12), 4048–4066. Seehaus, T., Cook, A.J., Silva, A.B., Braun, M., 2018. Changes in glacier dynamics in the northern Antarctic Peninsula since 1985. Cryosphere 12 (2), 577–594. Shevenell, A.E., Kennett, J.P., 2002. Antarctic Holocene climate change: a benthic foraminiferal stable isotope record from Palmer Deep. Paleoceanography 17 (2), PAL 91–PAL 9-12. Shevenell, A.E., Ingalls, A.E., Domack, E.W., Kelly, C., 2011. Holocene Southern Ocean surface temperature variability west of the Antarctic Peninsula. Nature 470 (7333), 250–254. Shuman, C.A., Stearns, C.R., 2001. Decadal-length composite inland West Antarctic temperature records. J. Clim. 14 (9), 1977–1988. Sigl, M., Winstrup, M., McConnell, J.R., Welten, K.C., Plunkett, G., Ludlow, F., Buntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O.J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D.R., Pilcher, J.R.,

variations over the past two millennia. PNAS 105 (36), 13252–13257. Mann, M.E., Zhang, Z., Rutherford, S., Bradley, R.S., Hughes, M.K., Shindell, D., Ammann, C., Faluvegi, G., Ni, F., 2009. Global signatures and dynamical origins of the Little Ice Age and Medieval climate anomaly. Science 326 (5957), 1256–1260. Markle, B.R., Bertler, N.A.N., Sinclair, K.E., Sneed, S.B., 2012. Synoptic variability in the Ross Sea region, Antarctica, as seen from back-trajectory modeling and ice core analysis. J. Geophys. Res. Atmos. 117 (D2) (p. n/a-n/a). Marshall, J., Armour, K.C., Scott, J.R., Kostov, Y., Hausmann, U., Ferreira, D., Shepherd, T.G., Bitz, C.M., 2014. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. 372 (2019). Martin-Español, A., Bamber, J.L., Zammit-Mangion, A., 2017. Constraining the mass balance of East Antarctica. Geophys. Res. Lett. 44 (9), 4168–4175. Masson, V., Vimeux, F., Jouzel, J., Morgan, V., Delmotte, M., Ciais, P., Hammer, C., Johnsen, S., Lipenkov, V.Y., Mosley-Thompson, E., Petit, J.-R., Steig, E.J., Stievenard, M., Vaikmae, R., 2000. Holocene climate variability in Antarctica based on 11 icecore isotopic records. Quat. Res. 54 (3), 348–358. Masson-Delmotte, V., Stenni, B., Jouzel, J., 2004. Common millennial-scale variability of Antarctic and Southern Ocean temperatures during the past 5000 years reconstructed from the EPICA Dome C ice core. The Holocene 14 (2), 145–151. Mayewski, P.A., Lyons, W.B., Zielinski, G., Twickler, M., Whitlow, S., Dibb, J., Grootes, P., Taylor, K., Whung, P.Y., Fosberry, L., Wake, C., Welch, K., 1995. An ice-core-based, Late Holocene history for the Transantarctic Mountains, Antarctica. In: Elliot, D.H., Blaisdell, G.L. (Eds.), Contributions to Antarctic Research IV. vol. 67. pp. 33–45. Mayewski, P.A., Maasch, K.A., Yan, Y., Kang, S., Meyerson, E.A., Sneed, S.B., Kaspari, S.D., Dixon, D.A., Osterberg, E.C., Morgan, V.I., Van Ommen, T., Curran, M.A.J., 2005. Solar forcing of the polar atmosphere. Ann. Glaciol. 41, 147–154. Mayewski, P.A., Maasch, K.A., Dixon, D., Sneed, S.B., Oglesby, R., Korotkikh, E., Potocki, M., Grigholm, B., Kreutz, K., Kurbatov, A.V., Spaulding, N., Stager, J.C., Taylor, K.C., Steig, E.J., White, J., Bertler, N.A.N., Goodwin, I., Simões, J.C., Jaña, R., Kraus, S., Fastook, J., 2013. West Antarctica's sensitivity to natural and human-forced climate change over the Holocene. J. Quat. Sci. 28 (1), 40–48. Mayewski, P.A., Carleton, A.M., Birkel, S.D., Dixon, D., Kurbatov, A.V., Korotkikh, E., McConnell, J., Curran, M., Cole-Dai, J., Jiang, S., Plummer, C., Vance, T., Maasch, K.A., Sneed, S.B., Handley, M., 2017. Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes. Quat. Sci. Rev. 155 (Supplement C), 50–66. Mehta, V.M., Lau, K.M., 1997. Influence of solar irradiance on the Indian Monsoon-ENSO relationship at decadal-multidecadal time scales. Geophys. Res. Lett. 24 (2), 159–162. Mezgec, K., Stenni, B., Crosta, X., Masson-Delmotte, V., Baroni, C., Braida, M., Ciardini, V., Colizza, E., Melis, R., Salvatore, M.C., Severi, M., Scarchilli, C., Traversi, R., Udisti, R., Frezzotti, M., 2017. Holocene sea ice variability driven by wind and polynya efficiency in the Ross Sea. Nat. Commun. 8 (1), 1334. Minzoni, R.T., Anderson, J.B., Fernandez, R., Wellner, J.S., 2015. Marine record of Holocene climate, ocean, and cryosphere interactions: Herbert Sound, James Ross Island, Antarctica. Quat. Sci. Rev. 129, 239–259. Moberg, A., Sonechkin, D.M., Holmgren, K., Datsenko, N.M., Karlén, W., Lauritzen, S.-E., 2005. Highly variable Northern Hemisphere temperatures reconstructed from lowand high-resolution proxy data. Nature 433 (613–617). Monien, P., Schnetger, B., Brumsack, H.-J., Hass, H.C., Kuhn, G., 2011. A geochemical record of late Holocene palaeoenvironmental changes at King George Island (maritime Antarctica). Antarct. Sci. 23 (3), 255–267. Morgan, V., Ommen, T.D.v., 1997. Seasonality in late-Holocene climate from ice-core records. The Holocene 7 (3), 351–354. Mosley-Thompson, E., 1996. Holocene climate changes recorded in an East Antarctica ice core. In: Jones, P.D., Bradley, R.S., Jouzel, J. (Eds.), Climatic Variations and Forcing Mechanisms of the Last 2000 Years. Springer Berlin Heidelberg, Berlin, Heidelberg, pp. 263–279. Moy, C.M., Seltzer, G.O., Rodbell, D.T., Anderson, D.M., 2002. Variability of El Niño/ Southern Oscillation activity at millennial timescales during the Holocene epoch. Nature 420, 162. Mulvaney, R., Oerter, H., Peel, D.A., Graf, W., Arrowsmith, C., Pasteur, E.C., Knight, B., Littot, G.C., Miners, W.D., 2002. 1000 year ice-core records from Berkner Island, Antarctica. Ann. Glaciol. 35, 45–51. Mulvaney, R., Abram, N.J., Hindmarsh, R.C.A., Arrowsmith, C., Fleet, L., Triest, J., Sime, L.C., Alemany, O., Foord, S., 2012. Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history. Nature 489, 141–144. Münch, T., Laepple, T., 2018. What climate signal is contained in decadal- to centennialscale isotope variations from Antarctic ice cores? Clim. Past 14 (12), 2053–2070. Münch, T., Kipfstuhl, S., Freitag, J., Meyer, H., Laepple, T., 2016. Regional climate signal vs. local noise: a two-dimensional view of water isotopes in Antarctic firn at Kohnen Station, Dronning Maud Land: Clim. Past 12 (7), 1565–1581. Münch, T., Kipfstuhl, S., Freitag, J., Meyer, H., Laepple, T., 2017. Constraints on postdepositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles. Cryosphere 11 (5), 2175–2188. Neukom, R., Gergis, J., 2012. Southern Hemisphere high-resolution palaeoclimate records of the last 2000 years. The Holocene 22 (5), 501–524. Neukom, R., Gergis, J., Karoly, D.J., Wanner, H., Curran, M., Elbert, J., Gonzalez-Rouco, F., Linsley, B.K., Moy, A.D., Mundo, I., Raible, C.C., Steig, E.J., van Ommen, T., Vance, T., Villalba, R., Zinke, J., Frank, D., 2014. Inter-hemispheric temperature variability over the past millennium. Nat. Clim. Chang. 4 (5), 362–367. Nicolas, J.P., Bromwich, D.H., 2014. New reconstruction of Antarctic near-surface temperatures: multidecadal trends and reliability of global reanalyses. J. Clim. 27 (21), 8070–8093. Nielsen, S.H.H., Koç, N.n., Crosta, X., 2004. Holocene climate in the Atlantic sector of the Southern Ocean: controlled by insolation or oceanic circulation? Geology 32 (4),

17

Palaeogeography, Palaeoclimatology, Palaeoecology 532 (2019) 109251

S. Lüning, et al.

Turner, J., Barrand, N.E., Bracegirdle, T.J., Convey, P., Hodgson, D.A., Jarvis, M., Jenkins, A., Marshall, G., Meredith, M.P., Roscoe, H., Shanklin, J., French, J., Goosse, H., Guglielmin, M., Gutt, J., Jacobs, S., Kennicutt, M.C., Masson-Delmotte, V., Mayewski, P., Navarro, F., Robinson, S., Scambos, T., Sparrow, M., Summerhayes, C., Speer, K., Klepikov, A., 2014. Antarctic climate change and the environment: an update. Polar Rec. 50 (3), 237–259. Turner, J., Lu, H., White, I., King, J.C., Phillips, T., Hosking, J.S., Bracegirdle, T.J., Marshall, G.J., Mulvaney, R., Deb, P., 2016. Absence of 21st century warming on Antarctic Peninsula consistent with natural variability. Nature 535, 411. Turney, C.S.M., Jones, R.T., Fogwill, C., Hatton, J., Williams, A.N., Hogg, A., Thomas, Z.A., Palmer, J., Mooney, S., Reimer, R.W., 2016. A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years. Clim. Past 12 (2), 189–200. Vance, T.R., Roberts, J.L., Plummer, C.T., Kiem, A.S., van Ommen, T.D., 2015. Interdecadal Pacific variability and eastern Australian megadroughts over the last millennium. Geophys. Res. Lett. 42 (1), 129–137. Vaughan, D.G., Marshall, G.J., Connolley, W.M., Parkinson, C., Mulvaney, R., Hodgson, D.A., King, J.C., Pudsey, C.J., Turner, J., 2003. Recent rapid regional climate warming on the Antarctic Peninsula. Clim. Chang. 60 (3), 243–274. Verleyen, E., Hodgson, D.A., Sabbe, K., Vyverman, W., 2004. Late Quaternary deglaciation and climate history of the Larsemann Hills (East Antarctica). J. Quat. Sci. 19 (4), 361–375. Vimeux, F., Masson, V., Jouzel, J., Petit, J.R., Steig, E.J., Stievenard, M., Vaikmae, R., White, J.W.C., 2001. Holocene hydrological cycle changes in the Southern Hemisphere documented in East Antarctic deuterium excess records. Clim. Dyn. 17 (7), 503–513. Volobuev, D.M., 2014. Central antarctic climate response to the solar cycle. Clim. Dyn. 42 (9), 2469–2475. Voskresenskiy, A.I., Chukanin, K.I., 1981. Air temperature above Antarctica during the 19th and 20th solar activity cycles. Polar Geogr. Geol 5 (2), 116–121. Wagner, B., Cremer, H., Hultzsch, N., Gore, D.B., Melles, M., 2004. Late Pleistocene and Holocene history of Lake Terrasovoje, Amery Oasis, East Antarctica, and its climatic and environmental implications. J. Paleolimnol. 32 (4), 321–339. Wyatt, M.G., Curry, J.A., 2014. Role for Eurasian Arctic shelf sea ice in a secularly varying hemispheric climate signal during the 20th century. Clim. Dyn. 42 (9), 2763–2782. Xiao, W., Esper, O., Gersonde, R., 2016. Last Glacial - Holocene climate variability in the Atlantic sector of the Southern Ocean. Quat. Sci. Rev. 135, 115–137. Yan, H., Sun, L., Wang, Y., Huang, W., Qiu, S., Yang, C., 2011. A record of the Southern Oscillation Index for the past 2,000 years from precipitation proxies. Nat. Geosci. 4, 611. Yang, J., Xiao, C., 2018. The evolution and volcanic forcing of the southern annular mode during the past 300 years. Int. J. Climatol. 38 (4), 1706–1717. https://doi.org/10. 1002/joc.5290. (p. n/a-n/a). Yang, J.-W., Han, Y., Orsi, A.J., Kim, S.-J., Han, H., Ryu, Y., Jang, Y., Moon, J., Choi, T., Hur, S.D., Ahn, J., 2018. Surface temperature in twentieth century at the Styx Glacier, Northern Victoria Land, Antarctica, From Borehole Thermometry. Geophys. Res. Lett. 45 (18), 9834–9842. Yu, Z., Beilman, D.W., Loisel, J., 2016. Transformations of landscape and peat-forming ecosystems in response to late Holocene climate change in the western Antarctic Peninsula. Geophys. Res. Lett. 43 (13), 7186–7195. Yuan, X., 2004. ENSO-related impacts on Antarctic sea ice: a synthesis of phenomenon and mechanisms. Antarct. Sci. 16 (4), 415–425. Zale, R., 1994. Changes in size of the Hope Bay Adélie penguin rookery as inferred from Lake Boeckella sediment. Ecography 17 (4), 297–304. Zhang, W., Wang, Y., Jin, F.-F., Stuecker, M.F., Turner, A.G., 2015. Impact of different El Niño types on the El Niño/IOD relationship. Geophys. Res. Lett. 42 (20), 8570–8576. Zhao, X.H., Feng, X.S., 2015. Correlation between solar activity and the local temperature of Antarctica during the past 11,000 years. J. Atmos. Sol. Terr. Phys. 122 (Supplement C), 26–33. Zwally, H.J., Li, J., Robbins, J.W., Saba, J.L., Yi, D., Brenner, A.C., 2015. Mass gains of the Antarctic ice sheet exceed losses. J. Glaciol. 61 (230), 1019–1036.

Salzer, M., Schupbach, S., Steffensen, J.P., Vinther, B.M., Woodruff, T.E., 2015. Timing and climate forcing of volcanic eruptions for the past 2,500 years. Nature 523 (7562), 543–549. Smith, K.L., Polvani, L.M., 2017. Spatial patterns of recent Antarctic surface temperature trends and the importance of natural variability: lessons from multiple reconstructions and the CMIP5 models. Clim. Dyn. 48 (7), 2653–2670. Smith, K.L., Chiodo, G., Previdi, M., Polvani, L.M., 2018. No surface cooling over Antarctica from the negative greenhouse effect associated with instantaneous quadrupling of CO2 concentrations. J. Clim. 31 (1), 317–323. Stammerjohn, S.E., Martinson, D.G., Smith, R.C., Yuan, X., Rind, D., 2008. Trends in Antarctic annual sea ice retreat and advance and their relation to El Niño–Southern Oscillation and Southern Annular Mode variability. J. Geophys. Res. 113. Steig, E.J., Hart, C.P., White, J.W.C., Cunningham, W.L., Davis, M.D., Saltzman, E.S., 1998. Changes in climate, ocean and ice-sheet conditions in the Ross embayment, Antarctica, at 6 ka. Ann. Glaciol. 27, 305–310. Steig, E.J., Morse, D.L., Waddington, E.D., Stuiver, M., Grootes, P.M., Mayewski, P.A., Twickler, M.S., Whitlow, S.I., 2000. Wisconsinan and Holocene climate history from an ice core at Taylor Dome, Western Ross Embayment, Antarctica. Geogr. Ann. Ser. A Phys. Geogr. 82 (2–3), 213–235. Steig, E.J., Schneider, D.P., Rutherford, S.D., Mann, M.E., Comiso, J.C., Shindell, D.T., 2009. Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature 457, 459. Steig, E.J., Ding, Q., White, J.W.C., Kuttel, M., Rupper, S.B., Neumann, T.A., Neff, P.D., Gallant, A.J.E., Mayewski, P.A., Taylor, K.C., Hoffmann, G., Dixon, D.A., Schoenemann, S.W., Markle, B.R., Fudge, T.J., Schneider, D.P., Schauer, A.J., Teel, R.P., Vaughn, B.H., Burgener, L., Williams, J., Korotkikh, E., 2013. Recent climate and ice-sheet changes in West Antarctica compared with the past 2,000 years. Nat. Geosci. 6 (5), 372–375. Steinhilber, F., Abreu, J.A., Beer, J., Brunner, I., Christl, M., Fischer, H., Heikkilä, U., Kubik, P.W., Mann, M., McCracken, K.G., Miller, H., Miyahara, H., Oerter, H., Wilhelms, F., 2012. 9,400 years of cosmic radiation and solar activity from ice cores and tree rings. Proc. Natl. Acad. Sci. 109 (16), 5967–5971. Stelling, J.M., Yu, Z., Loisel, J., Beilman, D.W., 2018. Peatbank response to late Holocene temperature and hydroclimate change in the western Antarctic Peninsula. Quat. Sci. Rev. 188, 77–89. Stenni, B., Curran, M.A.J., Abram, N.J., Orsi, A., Goursaud, S., Masson-Delmotte, V., Neukom, R., Goosse, H., Divine, D., van Ommen, T., Steig, E.J., Dixon, D.A., Thomas, E.R., Bertler, N.A.N., Isaksson, E., Ekaykin, A., Frezzotti, M., Werner, M., 2017. Antarctic climate variability at regional and continental scales over the last 2,000 years. Clim. Past 13, 1609–1634. Strother, S.L., Salzmann, U., Roberts, S.J., Hodgson, D.A., Woodward, J., Nieuwenhuyze, W.V., Verleyen, E., Vyverman, W., Moreton, S.G., 2015. Changes in Holocene climate and the intensity of Southern Hemisphere Westerly Winds based on a high-resolution palynological record from sub-Antarctic South Georgia. The Holocene 25 (2), 263–279. Sun, L., Xie, Z., Zhao, J., 2000. A 3,000-year record of penguin populations. Nature 407, 858. Suparta, W., Yatim, B., Mohd Ali, M.A., 2010. Solar forcing on antarctic terrestrial climate: a study by means of GPS observations. Acta Geophys. 58 (2), 374–391. Tang, M.S.Y., Chenoli, S.N., Samah, A.A., Hai, O.S., 2018. An assessment of historical Antarctic precipitation and temperature trend using CMIP5 models and reanalysis datasets. Polar Science 15, 1–12. Tavernier, I., Verleyen, E., Hodgson, D.A., Heirman, K., Roberts, S.J., Imura, S., Kudoh, S., Sabbe, K., De Batist, M., Vyverman, W., 2014. Absence of a Medieval climate anomaly, Little Ice Age and twentieth century warming in Skarvsnes, Lützow Holm Bay, East Antarctica. Antarct. Sci. 26 (5), 585–598. Thomas, E.R., van Wessem, J.M., Roberts, J., Isaksson, E., Schlosser, E., Fudge, T.J., Vallelonga, P., Medley, B., Lenaerts, J., Bertler, N., van den Broeke, M.R., Dixon, D.A., Frezzotti, M., Stenni, B., Curran, M., Ekaykin, A.A., 2017. Regional Antarctic snow accumulation over the past 1000 years. Clim. Past 13 (11), 1491–1513.

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