Glaciochemical evidence in an East Antarctica ice core of a recent

(AD 1450–1850) neoglacial episode

Yuansheng Li,1 Jihong Cole-Dai,2 and Liya Zhou3

Received 4 September 2008; revised 21 November 2008; accepted 16 February 2009; published 28 April 2009.

[1] Chemical analysis of a shallow (82.5 m) ice core from a location (DT263) in theessentially unexplored area of Princess Elizabeth Land, East Antarctica, has been used toconstruct a continuous, high-resolution 780-year (AD 1207–1996) glaciochemical record.During the twentieth century, snow accumulation rates and concentrations of chemicalspecies in snow appear to be stable with short-term variations, indicating relatively stableand warm climatic conditions. The period of AD 1450–1850 in this record ischaracterized by sharply reduced snow accumulation rates and decreased concentrations ofseveral chemical species that suffer postdepositional losses linked to very lowaccumulation rates. These characteristics are consistent with colder climatic conditionsand suggest that this is likely a neoglacial episode. The timing of this episode coincideswith the Little Ice Age (LIA), a relatively cold period in the Northern Hemispherebetween the beginning of the fifteenth century and the end of the nineteenth century.Evidence in ice core and sedimentary records also indicates neoglacial conditions in someSouthern Hemisphere locations during the general time frame of LIA. The DT263 record,along with a few published ice core records, points to the existence of an LIA-typeclimatic episode in Antarctica between the fifteenth century and the twentieth century.However, other Antarctic ice core records show no such evidence. Together, these recordshighlight the regional differences in Holocene climate variations in Antarctica. TheDT263 record suggests that colder and drier conditions prevailed during the LIA timeperiod at the eastern Indian Ocean sector of East Antarctica.

Citation: Li, Y., J. Cole-Dai, and L. Zhou (2009), Glaciochemical evidence in an East Antarctica ice core of a recent (AD 1450–1850)

neoglacial episode, J. Geophys. Res., 114, D08117, doi:10.1029/2008JD011091.

1. Introduction

[2] Knowledge of climate variations during the lastmillennium is highly relevant to understanding the globalclimate system and to predicting future climate changes[Bradley et al., 2003; Crowley, 2000]. Variations of naturalclimate forcings, such as solar irradiance and volcanism,contribute to climate fluctuations and these contributionsmust be accounted for, in order to identify and quantify thehuman impact on climate through emissions of greenhousegases and other atmospheric constituents [IPCC, 2007].Attribution of the contributions by natural forcings can beaccomplished with detailed data analysis and robust climatemodels using composites or reconstructions of paleoclimaterecords [e.g., Hegerl et al., 2003; von Storch et al., 2004].[3] The most prominent multicentury scale climate feature

in the last millennium is the relatively cold period called the

Little Ice Age (LIA), from approximately the beginning ofthe fifteenth century to the middle or end of the nineteenthcentury. Extensive evidence of LIA has been found widelyin Northern Hemisphere paleoclimate records [e.g., Bradleyet al., 2003; Crowley and North, 1991; O’Brien et al.,1995]. Sparse but important data from a few places in thelow latitudes and Southern Hemisphere [Hall and Denton,2002; Hendy et al., 2002; Lara and Villalba, 1993; Newtonet al., 2006; Seltzer and Rodbell, 2005; Thompson et al.,1986] suggest that climatic episodes similar to LIA probablyalso existed in those regions during the 500 years betweenAD 1400 and AD 1900. However, due mainly to the verylimited spatial coverage of paleoclimate records for theSouthern Hemisphere, existing data appear to be insufficientto support a single globally synchronous cold episodeduring the period of 1400–1900, as the name of ‘‘LittleIce Age’’ implies.[4] Ice cores have been an important source of paleoclimate

information. Recent ice core records have provided much ofthe evidence of climatic fluctuations during the last millenniumincluding LIA. For example, Fischer et al. [1998] discoveredclear evidence of colder temperatures and enhanced atmo-spheric aerosol loadings during the period of 1400–1900 in anumber of ice cores from northern Greenland. Other evidenceof LIA has been found in terrestrial records from the NorthernHemisphere [Grove, 1988; von Storch et al., 2004].

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1Polar Research Institute of China, Shanghai, China.2Department of Chemistry and Biochemistry, South Dakota State

University, Brookings, South Dakota, USA.3Ministry of Education Key Laboratory of Coast and Island Develop-

ment, School of Geographic and Oceanographic Sciences, NanjingUniversity, Nanjing, China.

Copyright 2009 by the American Geophysical Union.0148-0227/09/2008JD011091$09.00

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[5] High-resolution paleoclimate records are less abundantin the Southern Hemisphere and ice core records are often theonly records available. With regard to the LIA, very limitedice core data from South America [Thompson et al., 1986]show that LIA appears as a period of significantly increasedprecipitation and increased fluctuations in regional condi-tions. Unusual climatic conditions during the LIA time framehave been found in some Antarctica ice core records [e.g.,Kreutz et al., 1997;Morgan and Van Ommen, 1997;Mosley-Thompson, 1992], whereas other records [Mulvaney et al.,2002; Sommer et al., 2000] show no evidence of unusualclimate variations during the same time period.[6] Here we present the results of chemical analysis of an

ice core from the Princess Elizabeth Land in the Indian Oceansector of East Antarctica. These results provide strongevidence of an LIA type neoglacial episode approximatelyfrom 1450 to 1850.

2. Methods and Data

2.1. Ice Core

[7] As part of the International Trans-Antarctic ScientificExpedition (ITASE) program in Antarctica, the ChineseAntarctic Research Expedition (CHINARE) has since 1997conducted several inland traverses from Zhongshan Station

(69�300S, 76�200E) toward Dome Argus (Dome A, approx-imately 80�S, 77�E) in interior East Antarctica. The traversescovered essentially unexplored areas in Princess ElizabethLand where little is known about local and regional meteo-rological and glaciological conditions. During these tra-verses, shallow ice cores and samples from surface snowand snow pits have been collected from which basic glacio-logical information about this region can be extracted. In theaustral summer of 1998–1999, a shallow ice core was drilledby a CHINARE traverse team at a location (76�32.50S,77�01.50E, 2800 m.a.s.l., designated site DT263) betweenDome A and Zhongshan Station. This site, not located ona local dome or an ice divide, was chosen because it wasapproximately midway between Zhongshan and Dome A(Figure 1). The mean annual temperature at DT263 wasestimated to be �43�C, based on the temperature measuredat the depth of 10 m from the snow surface. The ice core,drilled with an electromechanical drill, started at approxi-mately 1.0 m from the 1999 snow surface and reached abottom depth of 82.5 meters. The 80-cm long cores of 9.5 cmin diameter were wrapped in clean plastic sheets, packed ininsulated crates, and shipped to the Polar Research Instituteof China (PRIC) in Shanghai, China. Density measurements,performed both in the field and at a PRIC lab, show that the

Figure 1. Map showing the locations of Zhongshan Station and the DT263 site in Princess ElizabethLand, East Antarctica. Contour lines are surface elevations in meters above sea level. Circles on thetraverse line indicate locations where ice cores, surface snow, and snowpit samples were taken.

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density at the bottom of the core is about 0.82 g cm�3 [Zhouet al., 2006]. Therefore the entire core was above the firn-icetransition depth, which is estimated to be at approximately90 m at this location.

2.2. Ice Core Sample Preparation and Analysis

[8] One half (cross section) of the DT263 core wasanalyzed for major chemical impurities in the ice core andenvironmental chemistry lab at South Dakota State Univer-sity (SDSU), South Dakota, USA. The entire length of thecore was mechanically cleaned (i.e., decontaminated via theremoval of exposed surface snow with a bandsaw) and cutvertically into 2232 snow or firn samples. The samples weremelted in precleaned containers under clean-air conditionsand subsequently analyzed by ion chromatography for theconcentrations of the following chemical species: sodium(Na+), ammonium (NH4

+), potassium (K+), magnesium,(Mg2+), calcium (Ca2+), methanesulfonate (MSA, CH3SO3

�),chloride (Cl�), nitrate (NO3

�), and sulfate (SO42�). The

decontamination and sample preparation procedures andion chromatography analytical methods have been fullydescribed elsewhere [Cole-Dai et al., 1995; Zhou et al.,2006].

2.3. Ice Core Dating

[9] Results of density measurements were used to modelor curve fit the density-depth relationship which was sub-sequently used to convert snow depths in core and of thesamples to depths in water equivalent [Zhou et al., 2006].As a result, the water equivalent depth at the bottom of the82.5 m core is found to be 53.6 m H2O.2.3.1. Annual Layer Counting[10] Initial examination of the Na+ concentration profile

(Figure 2a) versus depth indicated that Na+ exhibits regu-larly cyclic variations. Similar cyclic variations have beenobserved in other Antarctica ice cores and have been linkedto annual changes in the sources of the chemical species[Curran et al., 1998; Dibb and Whitlow, 1996; Legrand andDelmas, 1984]. These annual variations have been used todate ice cores by annual layer counting [Budner and Cole-Dai, 2003]. It appeared that the DT263 core could be datedusing annual cycles of Na+ concentration.[11] Dating by annual layer counting requires a fixed or

known age at a certain depth (usually the surface and theyear the core is drilled). Since the DT263 core did not beginat the 1999 snow surface, an event of known age in the corewas needed for annual layer counting. The first prominent

Figure 2. (a) Annual variations in Na+ concentration in the DT263 core used for annual layer counting.(b) The broad peak in the SO4

2� concentration at 0.35–0.45 m H2O is attributed to the fallout in 1993from the 1991 Pinatubo and Cerro Hudson volcanic eruptions. The 1999 snow surface at 0.36 m H2Oabove the top of the core (drilled in a 1-m snowpit) is estimated with the average annual accumulationrate of 0.12 m H2O.

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volcanic event in the core was found at the water equivalentdepth range of 0.35–0.45 m H2O (snow depth range 0.85–1.00 m). The most recent large explosive volcanic eruptionsare the June 1991 Pinatubo (15.14�N, 120.35�E) eruption inthe Philippines and the smaller August 1991 Cerro Hudson(45.92�S, 73.00�W) eruption in Chile. Both events havebeen found, often combined as a single sulfate event peakingin the 1993 snow layer, in several Antarctica ice cores[Castellano et al., 2005; Cole-Dai and Mosley-Thompson,1999; Cole-Dai et al., 1997;Dibb andWhitlow, 1996]. Usingthe Pinatubo/Hudson volcanic marker as a time reference(1993, Figure 2b) for annual layer counting, we determinedthat the snow at the top of the core (1.0 m from the 1999surface) was deposited in 1996. This yielded an averageaccumulation rate of 0.33 m snow or approximately 0.12 mH2O per year between 1996 and 1999 (Figure 2).[12] Discernable annual cycles could be found in Na+

concentration down to 17.0 m H2O. A total of 113 years(1883–1996) was counted using the Na+ annual cycles, withan uncertainty of ±8 years due to ambiguities in the shape ofseveral Na+ peaks. Since the Na+ annual peak appears duringthe fall/winter season in Antarctica [Budner and Cole-Dai,2003; Cole-Dai and Mosley-Thompson, 1999], we marked acalendar year between two adjacent Na+ valleys. For exam-ple, calendar year 1995 (January–December) is representedby the snow layer between 0.13–0.04 mH2O (Figure 2). Theaccuracy of the layer counting is supported by the dates oftwo prominent sulfate signals attributed to the Agung volcaniceruption (eruption date 1963, date in core 1963) and theKrakatoa eruption (eruption date 1883, date in core 1884).Details of the DT263 volcanic record have been describedelsewhere [Zhou et al., 2006].2.3.2. Volcanic Time Stratigraphic Markers[13] No clear annual cycles could be established below

the depth of 17 m H2O in the core, probably due to reducedannual layer thickness as a result of lowered accumulationrates (discussed later). To date the remainder of the core, werelied on the dates and identification of the outstandingsulfate signals of several large explosive volcanic eruptionsin the last 1000 years. For example, large sulfate signalsfrom the 1815 Tambora eruption, the Kuwae eruption of the1450s and the 1259 eruption of an unknown volcano havebeen found in all Antarctic ice cores dating back to thethirteenth century [Castellano et al., 2005; Cole-Dai et al.,2000; Delmas et al., 1992; Gao et al., 2006; Kurbatov et al.,2006]. We attributed [Zhou et al., 2006] the large sulfatedoublet at 21.5 m H2O to Tambora and an unknowneruption in 1809 [Dai et al., 1991]. Similarly, the very largesulfate peak at 33.6 m H2O is attributed to the 1453 Kuwaeeruption [Gao et al., 2006] and assigned a date of 1454.Finally, 5 large sulfate peaks are found in the depth range of46.5–51.1 m H2O; this is consistent with previous findingsof 5 volcanic events in the thirteenth century [Budner andCole-Dai, 2003; Langway et al., 1995]. We assigned theyear of 1260 to the largest of the 5 sulfate peaks and 1285 tothe latest.[14] Seven volcanic time stratigraphic markers between

17.0 m H2O and the bottom of the core (53.6 m H2O) weredesignated with known or expected dates (Table 1; note thatdates in core may lag behind the eruption dates by 1 or 2 years;the lag is required for the atmospheric transport of volcanicaerosols to Antarctica from the erupting volcanoes located in

the midlatitudes and low latitudes). Using the dates anddepths of the volcanic time markers, we calculated theaverage annual accumulation rates between two adjacentmarkers and converted the depth range of 53.6–17.0 mH2O into a timescale for the period of 1207 to 1883 AD.Together with the annually counted layers above 17 m H2O,the entire DT263 core represents the last 780 years (1207–1996) of accumulated snow at this site (Figure 3a). Forcomparison, the sulfate concentrations in a well-dated SouthPole ice core [Budner and Cole-Dai, 2003] are also shown ona timescale in Figure 3. The close alignment in time of nearlyall prominent volcanic events in the two cores indicates thatthe timescale of DT263 is consistent with that of the SouthPole core.

3. Results and Discussion

3.1. Time Scale Verification

[15] Hiatuses or missing snow layers may exist in ice corerecords, particularly in cores from low snow accumulationlocations. Evidence shows that, at East Antarctica locationswhere the accumulation rates are very low, partial loss orredistribution of deposited snow is common [Cole-Dai et al.,2000; van der Veen et al., 1999;Wolff et al., 1999]. At DT263,annual snow accumulation is substantially reduced during theperiod of 1450–1850 (see discussion below), raising thepossibility of hiatuses in the DT263 records. However, adetailed comparison of the volcanic records in both DT263and a number of well-dated Antarctica ice cores [Zhou et al.,2006] indicates that the DT263 volcanic record is consistentwith those from the other cores. For example, a prominentvolcanic eruption in the fourteenth century is dated at 1348(Figure 3) in the DT263 core, compared with the date of 1346in the well-dated South Pole core [Budner and Cole-Dai,2003]. In addition, several other prominent volcanic signalsin DT263 appear at the expected dates (Figure 3a, events initalics) established by the timescales of several other ice corerecords [Zhou et al., 2006]. The accurate dates in DT263 forthese volcanic signals suggest that there are no significanthiatuses in the DT263 ice core records.

3.2. Accumulation Rates

[16] Considerable, short term (yearly and decadal) varia-tions in annual accumulation rate over the twentieth centurycan be seen in the DT263 record (Figure 4 insert). However,the trend during the last 100 years appears to be relativelystable, with an average of 0.15mH2O per year and a standard

Table 1. Volcanic Time Stratigraphic Markers and Their Ages

Used for Dating the DT263 Corea

Volcanic Event Year in Core Depth in Core (m H2O)

Pinatubo 1991 1992–1993 0.35–0.45Krakatoa 1883 1884–1885 16.83Coseguina 1835 1835–1836 20.48Tambora 1815 1816–1818 21.45Unknown 1809 1809–1811 21.64Kuwae 1453 1453–1455 33.58Unknown 1284–1886 46.54Unknown 1259 1259–1261 48.81

aDates following volcano names are eruption years. The appearance ofPinatubo is used as a fixed time point for annual layer counting. See text fordetails.

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deviation of 0.05 m H2O. A dramatic shift occurs in thenineteenth century, when the annual accumulation increasedby a factor of 4 to 5 from very low values of the early 1800s tothe twentieth century average (Table 2). It is not clear if theincrease occurred abruptly or gradually over the course of thenineteenth century, due to the lack of annual accumulationdata. The most striking feature in long term trends over thelast 780 years (Figure 4 and Table 2), as estimated from thevolcanic time stratigraphic horizons, appears to be sharplylowered accumulation (0.03 m H2O per year) during theperiod from approximately 1450 to the early or mid-1800s.Average accumulation rates (0.08 m H2O per year) prior to1450, though approximately 50% lower than the twentiethcentury average, are markedly higher than that during the1450–1800s period (Table 2).[17] Long term variations in Antarctic precipitation and

snow accumulation rates appear to be directly related to andcontrolled by climate variations, with low accumulationperiods in general during cold time periods [e.g., EPICACommunity Members, 2004; Jouzel et al., 2007]. Thereforethe sharply reduced accumulation during 1450–1800s sug-gests that this region experienced unusually cold conditions.This will be further explored in later discussion on theexistence of a neoglacial episode during this time period.[18] An alternative interpretation of the drastic reduction

of accumulation rate in the 22.0–33.7 m H2O section of icein DT263 (approximately 1450–1850 in our timescale) maybe that ice flow brought this ice from a nearby low accumu-lation site to the DT263 site. Discontinuity or interruption of

temporally continuous snow deposition and preservation canoccur at locations where ice flow is complex [van der Veen etal., 1999]. Sommer et al. [2000] observed a significantdecrease (approximately 35% of the average accumulationin more recent time periods) in snow accumulation in anolder section (ca. AD 500–1100) of a 115 m ice core (B31)from the Dronning Maud Land region of Antarctica, whileno such decreases were found in two cores (B32 and B33)from the same region. The section in B31 with loweraccumulation rate was suspected to be snow deposited at anadjacent location with lower snow accumulation rate due todifferent surface and/or bedrock topography and moved tothe B31 site through horizontal ice flow [Sommer et al.,2000]. As the DT263 ice core was not drilled at an ice divideand the flow directions in this area are unknown, we areunable to assess the influence of ice flow on the ice corerecords. Our further discussion of the DT263 records is basedon the assumption that ice flow does not significantly impactthe preserved glaciochemical archives, even though wecannot rule out the possibility that the 1450–1850 ice inDT263, which we interpret to be the evidence for a neoglacialepisode, has resulted from a situation similar to the onedescribed by Sommer et al. [2000].

3.3. Temporal Variations of Chemical Composition

[19] Of the ions measured, sulfate or nonseasalt (nss)sulfate (nss sulfate is defined as the measured sulfate con-centration minus seasalt sulfate as calculated by the productof Na+ concentration and the SO4

2�/Na+ concentration ratio in

Figure 3. Prominent volcanic signals in (a) DT263 and (b) a well-dated South Pole ice core [Budnerand Cole-Dai, 2003]. Dates in parentheses are years when the volcanic events are found in the cores.DT263 volcanic events that are not italicized are used for dating the core (see Table 1).

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bulk seawater) exhibits the least temporal variation during the780-year period covered by this ice core record. As illustratedin Figure 5a, the mean annual average concentration ofnonvolcanic nss sulfate (years with known or probablevolcanic sulfate have been removed from the time series)appears to be stable over the entire period, with only a slightdecrease in the twentieth century (Table 3). Excludingoccasional and brief time periods impacted by explosivevolcanic eruptions, nss sulfate in Antarctic snow is dominatedby the emission and subsequent tropospheric oxidation ofbiogenic sulfur (in the form of dimehtylsulfide) from theocean surface waters [Legrand, 1997]. Aerosol measure-ments [Minikin et al., 1998] and modeling exercises [Cosmeet al., 2005; EPICA Community Members, 2004] suggest thatmost of themarine biogenic sulfur compounds originate in thehigh and midlatitude Southern Ocean. As a result, nonvol-canic nss sulfate is not significantly impacted by Holoceneclimate variations in the high southern latitudes [EPICACommunity Members, 2004]. This may explain the relativelystable nonvolcanic or background levels of sulfate or nsssulfate during the last 780 years at this location, whensignificant climatic shifts appear to have occurred (see dis-cussion later).[20] The dominant source of sodium and magnesium in

Antarctic snow is believed to be seasalt aerosols resultingfrom bursting bubbles of ocean spray [Legrand andMayewski,1997; Wagenbach et al., 1998]. Little or no chemical trans-formation occurs to Na+ and Mg2+ while the seasalt aerosolsare transported in the troposphere and distributed overAntarctica. Therefore Na+ and Mg2+ in Antarctic snow areindicators of the primary aerosol source of seasalts. In some

cases, Cl� may also be used to represent seasalt aerosols;however, due to Cl� chemical transformation in the atmo-sphere and in snow (see later discussion on Cl� loss fromsnow), such use is limited to locations where Cl� concen-trations are unusually high and/or data of other seasaltcomponents are unavailable. The main source areas of seasaltaerosols are generally considered to be the open water zonesof the high-latitude ocean surrounding Antarctica. As theseasalt aerosols are transported inland, large particles settleout of the atmosphere quickly and the seasalt concentration insnow decreases as the distance to the open sea increases[Legrand and Delmas, 1984; Suzuki et al., 2002]. In DT263,Na+ concentrations in the period of 1207–1450 appear littlechanged when compared to the twentieth century (Figure 5band Table 3). During the period of 1450–1800 and thenineteenth century, Na+ concentrations are lower than the

Figure 4. Snow accumulation rates over the last 780 years as recorded in the DT263 ice core.Accumulation rates for the period of 1884–1996 (inert) are based on measured annual layer thickness,and the data prior to 1884 are averages between volcanic time stratigraphic markers. Heavy linesrepresent smoothed data.

Table 2. Annual Accumulation Rates During Specific Time

Periods in the DT263 Recorda

Time PeriodAverage Accumulation

(m H2O a�1)

Deviation (%)

FromAD 1450–1810

From20th Century

1901–1996 0.148 +350 01884–1900 0.157 +375 +51810–1883 0.065 +97 �561451–1810(neoglacial)

0.033 0 �78

1207–1450 0.081 +145 �46aRates for the twentieth century and AD 1884–1900 are average values

of annual accumulation rates. All other rates are averages between volcanictime stratigraphic markers in Table 1.

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twentieth century mean by 39% and 23%, respectively. Suchdecreases are large when compared to the relatively stable nsssulfate over the same time periods. These decreases areconsistent with the fact that during the climatically coldertime period, sea-ice coverage in the source areas of seasaltaerosols was probably larger, and, therefore the distancebetween the open sea and the ice core site was consequently

longer, resulting in less seasalt aerosols arriving at theDT263 core site. Trends in Mg2+ data (Figuer 5c) can besimilarly explained, as the two ions share a common seasaltsource. There is evidence that, in coastal Antarctica loca-tions, the amounts of seasalt aerosols and seasalts in snowvary with the extent of nearby sea ice [Wagenbach et al.,1998; Hall and Wolff, 1998], not the distance to open water;

Figure 5. Temporal variations of the annual average concentrations of (a) nonvolcanic nss SO42�,

(b) Na+, (c) Mg2+; (d) Cl�, (e) MSA, and (f) NO3�. The cross-hatched period (AD 1450–1850) shows

neoglacial conditions (sharply reduced snow accumulation). Heavy lines represent smoothed data.

Table 3. Temporal Variations of Average Concentrations of Nonvolcanic Sulfate, Nonvolcanic nss Sulfate, Sodium,

Magnesium, Chloride, MSA, and Nitrate in the DT263 Corea

Time Period SO42� (Nonvolcanic) nss SO4

2� (Nonvolcanic) Na+ Mg2+ Cl� MSA NO3�

1901–1996 54.2 48.9 22.9 4.0 49.6 13.8 112.61801–1900 72.2 67.8 17.6 3.6 37.9 3.4 57.21451–1800 (neoglacial) 76.1 72.6 13.9 3.4 25.5 0.5 20.51207–1450 66.2 61.0 20.8 4.6 43.8 4.0 77.5

aAll concentration units are in mg L�1.

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in addition, it has been proposed [Wolff et al., 2003] that seaice may also be the dominant source of seasalts in centralAntarctica. It is possible, however, that seasalt amount insnow at an interior location may be dependent on either thedistance to open water or sea-ice coverage. Due to the lackof empirical data in the section of East Antarctica where theDT263 ice core was taken, we have chosen to interpret theseasalt variation in terms of distance to open water.[21] A very different pattern of temporal variations can be

seen in Cl�, MSA and NO3�. Significantly lowered concen-

trations of these species are seen during the period of 1450to approximately 1800 (Figures 5d–5f and Table 3). MSAand NO3

� are part of secondary aerosols and have gaseouscospecies during the aerosol transport and deposition pro-cesses [Wagnon et al., 1999; Weller et al., 2004]. Afterdeposition in snow, these species can be reemitted into theatmosphere through transformation to gaseous compounds[Delmas et al., 2003; Wagnon et al., 1999]. In general, thepostdepositional loss of such species from the snowpack ismost severe in locations of extremely low snow accumula-tion rates [Wagnon et al., 1999; Weller et al., 2004],indicating that the loss of gaseous compounds is enhancedby reduced snow accumulation rate. As such, the extremelylow concentrations of MSA and NO3

� during the period of1450–1800 are consistent with the sharply lowered accu-mulation rates during the same time period.[22] Although seasalt is a major source of Cl�, the

difference in the temporal trends of Na+ and Cl�, i.e.,much more pronounced decrease in Cl� during 1450–1800 (Figure 5d and Table 3), indicates that the increasedsea-ice coverage cannot fully account for the much moresignificant decrease of Cl� concentration than Na+ duringthe colder time period. The similarity between the sharpdecrease of Cl� and those of MSA and NO3

� during thisperiod suggests that an additional cause, one that is alsoresponsible for the MSA and NO3

� decreases, may beresponsible for the more significant loss of Cl�. Reactionsbetween seasalt particles and acid aerosols in air can convertCl� in seasalt into HCl [Legrand and Delmas, 1988].Similar reactions are also likely in the snowpack [Wagnonet al., 1999], generating HCl which can be emitted as a gasfrom snow surface, similar to the mechanism for the MSAand NO3

� loss. It appears that the Cl� pattern, with concen-tration decreases during 1450–1800 between that of Na+

and those of MSA and NO3�, is the result of both reduced

seasalt input and enhanced postdepositional loss. However,the postdepositional loss of Cl� is not as severe as that ofMSA and NO3

�, as at least some Cl� in snow is associatedwith seasalt cations (Na+, Mg2+).

3.4. Neoglacial Episode in East Antarctica

[23] The sharply reduced accumulation rates and concen-trations of several of the ionic species with gaseous cospe-cies during the period from the fifteenth century to thenineteenth century suggest that the period is climaticallyunusual. Reduced precipitation usually accompanies coldertemperatures, such as seen in the glacial periods in polar icecore records [EPICA Community Members, 2004; Legrandand Mayewski, 1997; Petit et al., 1999]. In available butlimited paleoclimate data from the Southern Hemisphere,the relationship between precipitation and temperatureappears to be much less straight forward for periods within

the Holocene epoch. In ice cores from the Quelccaya ice capin tropical South America, it was found that significantlyincreased precipitation accompanied cold temperaturesduring the early part of LIA [Thompson et al., 1985, 1986].This wet-cold correlation is supported by evidence fromlacustrine records showing positive water balance accompa-nying glacial advances [Fritz et al., 2007]. However, reducedprecipitation was observed during the late part of the coldLIA period in the Quelccaya records [Thompson et al., 1986].[24] It appears that, during the last 1000 years, relatively

cold climatic conditions have impacted regions in the tropicsand South America. In addition to the ice core and lakesediment records from Bolivia and Peru [Thompson et al.,1986; Fritz et al., 2007], evidence of the onset of an LIA-typeneoglacial event around AD 1450 was found in the tropicalAndes [Seltzer and Rodbell, 2005] and in southern SouthAmerica [Lara and Villalba, 1993]. Marine sediment recordsshow that the LIA period is characterized by colder temper-atures and lowered salinity in the tropical Pacific [Hendy etal., 2002; Newton et al., 2006].[25] There is also evidence of neoglacial episodes in

Antarctica ice cores. Kreutz et al. [1997] found that theLIA period (�1400–1900) was characterized by increasedvariability in circulation over West Antarctica. Morgan andVan Ommen [1997] found generally low temperatures forthe period of 1350–1800 (with a few brief periods ofrelative warmth) at Law Dome, a coastal East Antarcticalocation. Karlof et al. [2000] presented a 1500-year recordof accumulation at a location in Dronning Maud Land, inwhich a significant reduction in annual accumulation ratewas found for the period of 1450–1650: 8% compared tothe average accumulation of the twentieth century. Stenni etal. [2002] reported colder conditions between the mid-1500s and early 1800s at Northern Victoria Land, EastAntarctica. However, other Antarctic ice core records sug-gest otherwise. For example, no evidence of colder climaticconditions was found in ice cores from Berkner Island[Mulvaney et al., 2002], and Dronning Maud Land [Sommeret al., 2000].[26] Stable isotope composition of water (d18O and dD) in

ice cores has been used as proxies for tropospheric temper-atures [e.g., EPICA Community Members, 2004; Rozanskiet al., 1992]. Although no isotopic measurements havebeen performed on the DT263 core, we discuss here thepossibility that the recent neoglacial episode may or may notbe recorded in the d18O proxy. The LIA signal in the SipleDome, West Antarctica ice core is represented by increasedwind intensities and circulation variability, but not by de-creased isotope values of the ice [Kreutz et al., 1997]. Instead,somewhat warmer conditions during this period may haveprevailed in parts of West Antarctica [Kreutz et al., 1997;Mosley-Thompson, 1992], which was attributed to the en-hanced influence of warm marine air masses during LIA[Kreutz et al., 1997]. There is evidence that snow isotopiccomposition may reflect single-season temperatures due tothe preservation of only one season’s snow at a given site[Morgan and Van Ommen, 1997], particularly at low accu-mulation locations. If a climatic shift is limited to temperaturechange in one season, it probably will not be reflected inthe isotopic composition of snow of other seasons. Theextremely low snow accumulation during the period of1450–1850 at DT263 raises the possibility that only winter

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or summer snow is preserved and recovered in the ice core;therefore the isotope records may be biased due to the lackof either summer or winter snow, making the interpretationof those records difficult in terms of the climate history inthis area.[27] High-resolution records of marine sediments from

the Antarctic Peninsula region [Domack et al., 2001; Fabreset al., 2000; Shevenell and Kennett, 2002] indicate that thelate Holocene period of �700 years before present (approx-imately AD 1300–1900) is characterized by oceanographicconditions consistent with an LIA-type neoglacial. Roberts etal. [2001] correlated records of evaporation-salinity of lakesediments in coastal Princess Elizabeth Land with ice coreisotope records of Law Dome and found that much coolerconditions prevailed in this region during 1750–1850. Sig-nificant glacier advance during the LIA time period wasalso found in the Ross Sea region of Antarctica [Hall andDenton, 2002].[28] All of these suggest that regional differences are

significant for Holocene climate variations in Antarctica,and that even if a continent-wide LIA-type neoglacial epi-sode existed, its manifestation and recording varied widelywithin Antarctica. The DT263 records suggest that colderand drier conditions may have prevailed during the 500 yearsbetween the beginning of the fifteenth century and the end ofthe nineteenth century at the eastern Indian Ocean sector ofEast Antarctica.[29] The causes of LIA have been rigorously debated and

various hypotheses suggest that reduced solar activities areprimarily responsible [e.g., Bradley et al., 2003]. However,recent studies [Crowley et al., 2008;Gao et al., 2008] suggestthat enhanced volcanism can account for most of thetemperature decreases during the latter half of LIA in theNorthern Hemisphere. In addition, regionally importantfactors such as ENSO variations [Meyerson et al., 2002]and changes in atmospheric circulation patterns [Kreutz etal., 1997; Meyer and Wagner, 2008] may be responsible forsome of the temperature decreases, and can enhance (ordiminish) the effects of the climatic forcing(s) throughfeedback mechanisms.

4. Conclusions

[30] A shallow ice core from the Princess Elizabeth Landregion of East Antarctica was analyzed for chemical com-position. The chemical records from this core cover thelast 780 years (AD 1207–1996). Snow annual accumulationrates calculated from annually dated snow layers and fromvolcanic time stratigraphic markers indicate that the averageaccumulation rate during the period between the mid-fifteenth century and the early or mid-nineteenth centurywas much reduced compared with those of the earlier period(the early thirteenth century to the mid-fifteenth century)and the later period (the late nineteenth century to the end ofthe twentieth century). For instance, the average accumula-tion rate between 1450 and 1810 is nearly 80% lower thanthe twentieth century average. Such sharply reduced accu-mulation suggests that the climate conditions in this regionduring this period of 400 years (approximately 1450–1850)were colder than the earlier and later periods. Furtherevidence of reduced accumulation and therefore of colder

climate during this period is found in the decreased con-centrations of chemical species that are reversibly depositedin snow.[31] This period of unusually cold climate conditions in

the eastern Indian Ocean sector in East Antarctica coincideswith the time frame of the Little Ice Age, which has beenfound to be a common neoglacial episode in many NorthernHemisphere locations and in a few places in the SouthernHemisphere. However, evidence from Antarctica ice corerecords does not consistently support a continent-wideneoglacial episode between the beginning of the fifteenthcentury and the end of the nineteenth century. Thereforeregional differences in Antarctic climate variations during theLIA time period appear to be very important when assessingclimate history during the last millennium.[32] Due to the general lack of glaciological information

(e.g., ice flow) from this region of Antarctica, the conclu-sions based on the DT263 record are tentative and will needto be verified by additional information from ice cores andother glaciological archives in this region.

[33] Acknowledgments. We are indebted tomembers of the CHINAREThird Inland Traverse (1998/1999) team for collecting the ice core and snowsamples. We thank three anonymous reviewers for their thoughtful andconstructive comments, which helped improve the original manuscript. Thisresearchwas supported in part byNatural Science Foundation of China grantsNSFC 49973006/D03, 40773074/D0309, 40703019/D0309 and Ministry ofScience and Technology of China grant MSTC 2006BAB18B01 (Y. Li) andU.S. National Science Foundation grants NSF 0049082, 0087151, 0337933,and 0538553 (J. Cole-Dai).

ReferencesBradley, R. S., K. R. Briffa, J. Cole, M. K. Hughes, and T. J. Osborn(2003), The climate of the last millennium, in Paleoclimate, GlobalChange, and the Future, edited by K. Alverson et al., pp. 105–141,Springer, New York.

Budner, D., and J. Cole-Dai (2003), The number and magnitude of largeexplosive volcanic eruptions between 904 and 1865 A.D.: Quantitativeevidence from a new South Pole ice core, in Volcanism and the Earth’sAtmosphere, edited by A. Robock and C. Oppenheimer, pp. 165–176,AGU, Washington, D. C.

Castellano, E., S. Becagli, M. Hansson, M. Hutteli, J. R. Petit, M. R.Rampino, M. Severi, J. P. Steffensen, R. Traversi, and R. Udisti(2005), Holocene volcanic history as recorded in the sulfate stratigraphyof the European Project for Ice Coring in Antarctica Dome C (EDC96)ice core, J. Geophys. Res., 110, D06114, doi:10.1029/2004JD005259.

Cole-Dai, J., and E. Mosley-Thompson (1999), The Pinatubo eruption inSouth Pole snow and its potential value to ice-core paleovolcanic records,Ann. Glaciol., 29, 99–105.

Cole-Dai, J., L. G. Thompson, and E. Mosley-Thompson (1995), A 485year record of atmospheric chloride, nitrate and sulfate: Results of che-mical analysis of ice cores from Dyer Plateau, Antarctica Peninsula, Ann.Glaciol., 21, 182–188.

Cole-Dai, J., E. Mosley-Thompson, and L. G. Thompson (1997), Annuallyresolved southern hemisphere volcanic history from two Antarctic icecores, J. Geophys. Res., 102(D14), 16,761–16,771.

Cole-Dai, J., E. Mosley-Thompson, S. P.Wight, and L. G. Thompson (2000),A 4100-year record of explosive volcanism from an East Antarctica icecore, J. Geophys. Res., 105(D19), 24,431–24,441.

Cosme, E., F. Hourdin, C. Genthon, and P. Martinerie (2005), Origin ofdimethylsulfide, non-sea-salt sulfate, and methanesulfonic acid in easternAntarctica, J. Geophys. Res., 110, D03302, doi:10.1029/2004JD004884.

Crowley, T. J. (2000), Causes of climate change over the past 1000 years,Science, 289, 270–277.

Crowley, T. J., and G. R. North (1991), Paleoclimatology, Oxford Univ.Press, New York.

Crowley, T. J., G. A. Zielinski, B. Vinther, R. Udisti, K. J. Kreutz, J. Cole-Dai,and E. Castellano (2008), Volcanism and the Little Ice Age, PAGES News,16(2), 22–23.

Curran, M. A. J., T. D. Van Ommen, and V. Morgan (1998), Seasonalcharacteristics of the major ions in the high-accumulation Dome SummitSouth ice core, Law Dome, Antarctica, Ann. Glaciol., 27, 385–390.

D08117 LI ET AL.: NEOGLACIAL EPISODE IN ANTARCTICA

9 of 11

D08117

Dai, J., E. Mosley-Thompson, and L. G. Thompson (1991), Ice core evidencefor an explosive tropical volcanic eruption 6 years preceding Tambora,J. Geophys. Res., 96(D9), 17,361–17,366.

Delmas, R. J., S. Kirchner, J. M. Palais, and J.-R. Petit (1992), 1000 yearsof explosive volcanism recorded at the South Pole, Tellus, 44B(4), 335–350.

Delmas, R. J., P. Wagnon, K. Goto-Azuma, K. Kamiyama, and O. Watanabe(2003), Evidence for the loss of snow-deposited MSA to the interstitialgaseous phase in central Antarctic firn, Tellus, 55B, 71–79.

Dibb, J. E., and S. I. Whitlow (1996), Recent climate anomalies and theirimpact on snow chemistry at South Pole, Geophys. Res. Lett., 23(10),1115–1118.

Domack, E., A. Leventer, R. Dunbar, F. Taylor, S. Brachfeld, C. Sjunneskog,and ODP Leg 178 Scientific Party (2001), Chronology of the Palmer Deepsite, Antarctic Peninsula: A Holocene palaeoenvironmental reference forthe circum-Antarctic, The Holocene, 11(1), 1–9.

EPICA Community Members (2004), Eight glacial cycles from an Antarcticice core, Nature, 429, 623–627, doi:10.1038/nature02599.

Fabres, J., A. Calafat, M. Canals, M. A. Barcena, and J. A. Flores (2000),Bransfield Basin fine-grained sediments: Late-Holocene sedimentary pro-cesses and Antarctic oceanographic conditions, The Holocene, 10(6),703–718.

Fischer, H., M. Werner, and D. Wagenbach (1998), Little ice age clearlyrecorded in northern Greenland ice cores, Geophys. Res. Lett., 25(10),1749–1752.

Fritz, S. C., P. Tapia, P. A. Baker, A. Ballantyne, G. O. Seltzer, H. Cheng,and R. L. Edwards (2007), Quaternary glaciation and hydrologic varia-tion in the South American tropics as reconstructed from the LakeTiticaca drilling project, Quat. Res., 68(3), 410–420, doi:10.1016/j.yqres.2007.07.008.

Gao, C., A. Robock, S. Self, J. B. Witter, J. P. Steffensen, H. B. Clausen,M.-L. Siggaard-Anderson, S. Johnsen, P. A. Mayewski, and C. M. Ammann(2006), The 1452 or 1453A.D.Kuwae eruption signal derived frommultipleice core records: Greatest volcanic sulfate event of the last 700 years,J. Geophys. Res., 111, D12107, doi:10.1029/2005JD006710.

Gao, C., A. Robock, and C. M. Ammann (2008), Volcanic forcing ofclimate over the past 1500 years: An improved ice-core-based indexfor climate models, J. Geophys. Res., 113, D23111, doi:10.1029/2008JD010239.

Grove, J. M. (1988), The Little Ice Age, Cambridge Univ. Press, New York.Hall, J. S., and E. W. Wolff (1998), Causes of seasonal and daily variationsin aerosol sea-salt concentrations at a coastal Antarctic station, Atmos.Environ., 32(21), 3669–3677.

Hall, B. L., and G. H. Denton (2002), Holocene history of the WilsonPiedmont Glacier along the southern Scott Coast, Antarctica, The Holocene,12(5), 619–627, doi:10.1191/0959683602hl572rp.

Hegerl, G. C., T. J. Crowley, S. K. Baum, K.-Y. Kim, and W. T. Hyde(2003), Detection of volcanic, solar and greenhouse gas signals in paleo-reconstructions of Northern Hemisphere temperature, Geophys. Res.Lett., 30(5), 1242, doi:10.1029/2002GL016635.

Hendy, E. J., M. K. Gagan, C. A. Alibert, M. T. McCulloch, J. M. Lough,and P. J. Isdale (2002), Abrupt decrease in tropical Pacific sea surfacesalinity at the end of Little Ice Age, Science, 295, 1511–1514.

IPCC (2007), Climate Change 2007: The Physical Science Basis. Contri-bution of Working Group I to the Fourth Assessment Report of the Inter-governmental Panel on Climate Change, 996 pp., Cambridge Univ.Press, New York.

Jouzel, J., et al. (2007), Orbital and millennial Antarctic climate variabilityover the past 800,000 years, Science, 317, 793 –796, doi:10.1126/science.1141038.

Karlof, L., et al. (2000), A 1500 year Record of Accumulation at Amund-senisen Western Dronning Maud Land, Antarctica, Derived from electri-cal and radioactive measurements on a 120 m ice core, J. Geophys. Res.,105(D10), 12,471–12,483.

Kreutz, K. J., P. A. Mayewski, L. D. Meeker, M. S. Twickler, S. I. Whitlow,and I. I. Pittalwala (1997), Bipolar changes in atmospheric circulationduring the Little Ice Age, Science, 277, 1294–1296.

Kurbatov, A. V., G. A. Zielinski, N. W. Dunbar, P. A. Mayewski, E. A.Meyerson, S. B. Sneed, and K. C. Taylor (2006), A 12,000 year record ofexplosive volcanism in the Siple Dome Ice Core, West Antarctica,J. Geophys. Res., 111, D12307, doi:10.1029/2005JD006072.

Langway, C. C. J., K. Osada, H. B. Clausen, C. U. Hammer, and H. Shoji(1995), A 10-century comparison of prominent bipolar volcanic events inice cores, J. Geophys. Res., 100(D8), 16,241–216,247.

Lara, A., and R. Villalba (1993), A 3620-year temperature record fromFitzroya cupressoides tree rings in Southern South America, Science,260, 1104–1106.

Legrand, M. (1997), Ice-core records of atmospheric sulphur, Philos. Trans.R. Soc. London, 352, 241–250.

Legrand, M. R., and R. J. Delmas (1984), The ionic balance of Antarcticsnow: A 10-year detailed record, Atmos. Environ., 18(9), 1867–1874.

Legrand, M. R., and R. J. Delmas (1988), Formation of HCl in the Antarcticatmosphere, J. Geophys. Res., 93(D6), 7153–7168.

Legrand, M., and P. A. Mayewski (1997), Glaciochemistry of polar icecore: A review, Rev. Geophys., 35(5), 219–243.

Meyer, I., and S. Wagner (2008), The Litte Ice Age in southern Patagonia:Comparison between paleoecological reconstructions and downscaledmodel output of a GCM simulation, PAGES News, 16(2), 12–13.

Meyerson, E. A., P. A. Mayewski, K. J. Kreutz, L. D. Meeker, S. Whitlow,and M. S. Twickler (2002), The polar expression of ENSO and sea-icevariability as recorded in a South Pole ice core, Ann. Glaciol., 35, 430–436.

Minikin, A., M. Legrand, J. Hall, D. Wagenbach, C. Kleefeld, E. Wolff,E. C. Pasteur, and F. Ducroz (1998), Sulfur-containing species (sulfateand methanesulfonate) in coastal Antarctic aerosol and precipitation,J. Geophys. Res., 103(D9), 10,975–10,990.

Morgan, V., and T. D. Van Ommen (1997), Seasonality in late-Holoceneclimate from ice-core records, The Holocene, 7, 351–354.

Mosley-Thompson, E. (1992), Paleoenvironmental conditions in Antarcticasince A.D. 1500: Ice core evidence, in Climate Since A.D. 1500, editedby R. S. Bradley and P. D. Jones, pp. 572–591, Routledge, New York.

Mulvaney, R., H. Oerter, D. A. Peel, W. Graf, C. Arrowsmith, E. C. Pasteur,B. Knight, G. C. Littot, and W. D. Miners (2002), 1000 year ice-corerecords from Berkner Island, Antarctica, Ann. Glaciol., 35, 45–51.

Newton, A., R. Thunell, and L. Stott (2006), Climate and the hydrographicvariability in the Indo-Pacific Warm Pool during the last millennium,Geophys. Res. Lett., 33, L19710, doi:10.1029/2006GL027234.

O’Brien, S. R., P. A. Mayewski, L. D. Meeker, D. A. Meese, M. S. Twickler,and S. I. Whitlow (1995), Complexity of Holocene climate as recon-structed from a Greenland ice core, Science, 270, 1962–1964.

Petit, J. R., et al. (1999), Climate and atmospheric history of the past420,000 years from the Vostok ice core, Nature, 399, 429–436.

Roberts, D., T. D. Van Ommen, A. McMinn, V. Morgan, and J. L. Roberts(2001), Late-Holocene East Antarctic climate trends from ice-core andlake-sediment proxies, The Holocene, 11(1), 117–120.

Rozanski, K., L. Araguas-Araguas, and R. Gonfiantini (1992), Relationbetween long-term trends of oxygen-18 isotope composition of precipita-tion and climate, Science, 258, 981–985.

Seltzer, G. O., and D. T. Rodbell (2005), Delta progradation and Neogla-ciation, Laguna Paron, Cordillera Blanca, Peru, J. Quat. Sci., 20(7–8),715–722.

Shevenell, A., and J. P. Kennett (2002), Antarctic Holocene climatechange: A benthic foraminiferal stable isotope record from PalmerDeep, Paleoceanography, 17(2), 1019, doi:10.1029/2000PA000596.

Sommer, S., C. Appenzeller, R. Rothlisberger, M. A. Hutterli, B. Stauffer,D. Wagenbach, H. Oerter, F. Wilhelms, H. Miller, and R. Mulvaney(2000), Glacio-chemical study spanning the past 2 kyr on three ice coresfrom Dronning Maud Land, Antarctica: 1. Annually resolved accumula-tion rates, J. Geophys. Res., 105(D24), 29,411–29,421.

Stenni, B., M. Proposito, R. Gragnani, O. Flora, J. Jouzel, S. Falourd, andM. Frezzotti (2002), Eight centuries of volcanic signal and climatechange at Talos Dome (East Antarctica), J. Geophys. Res., 107(D9),4076, doi:10.1029/2000JD000317.

Suzuki, T., Y. Iizuka, K. Matsuoka, T. Furukawa, K. Kamiyama, andO. Watanabe (2002), Distribution of sea salt components in snow coveralong the traverse route from the coast to Dome Fuji station 1000 km inlandat east Dronning Maud Land, Antarctica, Tellus, 54B(4), 407–411.

Thompson, L. G., E. Mosley-Thompson, J. F. Bolzan, and B. R. Koci(1985), A 1500-year record of tropical precipitation in ice cores fromthe Quelccaya ice cap, Peru, Science, 229, 971–973.

Thompson, L. G., E. Mosley-Thompson, W. Dansgaard, and P. M. Grootes(1986), The Little Ice Age as recorded in the stratigraphy of the tropicalQuelccaya ice cap, Science, 234, 361–364.

van der Veen, C., E. Mosley-Thompson, A. J. Gow, and B. G. Mark (1999),Accumulation at South Pole: Comparison of two 900-year records,J. Geophys. Res., 104(D24), 31,067–31,076.

von Storch, H., E. Zorita, J. M. Jones, Y. Dimitrieve, F. Gonzalez-Rouco,and S. F. B. Tett (2004), Reconstructing past climate from noisy data,Science, 306, 679–682.

Wagenbach, D., F. Ducroz, R. Mulvaney, L. Keck, A. Minikin, M. Legrand,J. S. Hall, and E. W. Wolff (1998), Sea-salt aerosol in coastal Antarcticregions, J. Geophys. Res., 103(D9), 10,961–10,974.

Wagnon, P., R. J. Delmas, and M. Legrand (1999), Loss of volatile acidspecies from upper firn layers at Vostok, Antarctica, J. Geophys. Res.,104(D3), 3423–3431.

Weller, R., F. Traufetter, H. Fischer, H. Oerter, C. Piel, and H. Miller(2004), Postdepostional losses of methane sulfonate, nitrate, and chlorideat the European Project for Ice Coring in Antarctica deep-drilling site in

D08117 LI ET AL.: NEOGLACIAL EPISODE IN ANTARCTICA

10 of 11

D08117

Dronning Maud Land, Antarctica, J. Geophys. Res., 109, D07301,doi:10.1029/2003JD004189.

Wolff, E., I. Basile, J. R. Petit, and J. Schwander (1999), Comparison ofHolocene electrical records from Dome C and Vostok, Antarctica, Ann.Glaciol., 29, 89–93.

Wolff, E. W., A. M. Ranking, and R. Rothlisberger (2003), An ice coreindicator of Antarctic sea ice production?, Geophys. Res. Lett., 30(22),2158, doi:10.1029/2003GL018454.

Zhou, L., Y. Li, J. Cole-Dai, D. Tan, B. Sun, J. Ren, L. Wei, and H. Wang(2006), A 780-year volcanic record from theDT263 ice core, EastAntarctica,Chin. Sci. Bull., 51(18), 2189–2197.

�����������������������J. Cole-Dai, Department of Chemistry and Biochemistry, South Dakota

State University, Box 2202, Brookings, SD 57007, USA. (jihong.cole-dai@sdstate.edu)Y. Li, Polar Research Institute of China, 451 Jinqiao Road, Pudong,

Shanghai 200136, China. (lysh@pric.gov.cn)L. Zhou, Ministry of Education Key Laboratory of Coast and Island

Development, School of Geographic and Oceanographic Sciences, NanjingUniversity, Nanjing 210093, China. (liyazhou@nju.edu.cn)

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