Date (Creation)

2019-10-03

Date (Revision)

2019-10-03

Date (Publication)

2019-10-03

Date (released)

2019-10-03

Edition

1.0

Unique resource identifier

https://doi.org/10.5285/df50e30a-0672-461a-928e-aafafb45fd55

Codespace

doi

Unique resource identifier

GB/NERC/BAS/PDC/01244

Codespace

https://data.bas.ac.uk/

Unique resource identifier

NE/J500173/1

Codespace

award

Other citation details

Please cite this item as: Roberts, S., Pearson, E., Foster, L., & Juggins, S. (2019). Chronological and biomarker reconstructed mean summer air temperatures (MSAT) for the past 6,000 years from lake sediments on Annenkov Island (near South Georgia) and the South Shetland Islands (Version 1.0) [Data set]. UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation. https://doi.org/10.5285/df50e30a-0672-461a-928e-aafafb45fd55

Credit

No credit.

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey, Natural Environment Research Council, UK Research & Innovation	Roberts, Stephen		Author
School of Geography, Politics and Sociology, Newcastle University	Pearson, Emma		Author
University College Dublin, School of Earth Sciences, Dublin, Ireland	Foster, Louise		Author
School of Geography, Politics and Sociology, Newcastle University	Juggins, Steven		Author
NERC EDS UK Polar Data Centre		PDCServiceDesk@bas.ac.uk	Point of contact

Maintenance and update frequency

As needed

Maintenance note

Completed

Global Change Master Directory (GCMD) Science Keywords

• EARTH SCIENCE > Atmosphere > Atmospheric Temperature > Air Temperature
• EARTH SCIENCE > Paleoclimate > Ocean/Lake Records > Sediments
• EARTH SCIENCE > Paleoclimate > Paleoclimate Reconstructions > Air Temperature Reconstruction

Theme

• Antarctic

• GDGT

• Palaeoclimate

• Southern Hemisphere

• organic geochemistry

• palaeolimnology

• temperature reconstruction

Place

• Fan Lake, Annenkov Island Antarctica

• Yanou Lake, Fildes Peninsula, King George Island Antarctica

GEMET - INSPIRE themes, version 1.0

• Atmospheric conditions
• Geology

Access constraints

Other restrictions

Other constraints

no limitations to public access

Access constraints

Other restrictions

Other constraints

no limitations

Use constraints

License

Other constraints

Open Government Licence v3.0

Use constraints

Other restrictions

Other constraints

Fan Lake

Foster et al. (2016) Development of a regional glycerol dialkyl glycerol tetraether (GDGT)-temperature calibration for Antarctic and sub-Antarctic lakes. Earth and Planetary Science Letters, 433. 370-379. https://doi.org/10.1016/j.epsl.2015.11.018

Strother et al. (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. https://doi.org/10.1177/0959683614557576

Yanou Lake

Roberts et al. (2017) Past penguin colony responses to explosive volcanism on the Antarctic Peninsula. Nature Communications, 8, 14914. 16, pp. https://doi.org/10.1038/ncomms14914

Use constraints

Other restrictions

Other constraints

No restrictions apply.

Unique resource identifier

url

Codespace

url

Association Type

Cross reference

Unique resource identifier

url

Codespace

url

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Spatial representation type

Text, table

Language

English

Character set

UTF8

Topic category

• Climatology, meteorology, atmosphere
• Environment

Begin date

2007-01-01

End date

2016-12-31

Supplemental Information

It is recommended that careful attention be paid to the contents of any data, and that the author be contacted with any questions regarding appropriate use. If you find any errors or omissions, please report them to polardatacentre@bas.ac.uk.

Title

European Petroleum Survey Group (EPSG) Geodetic Parameter Registry

Date (Publication)

2008-11-12

Cited responsible party

Organisation name	Individual name	Electronic mail address	Role
European Petroleum Survey Group		EPSGadministrator@iogp.org	Publisher

Unique resource identifier

urn:ogc:def:crs:EPSG::3031

Version

6.18.3

Hierarchy level

Dataset

Statement

Methodology:

Reconstructed Temperature datasets:

Sediment cores were taken from Fan Lake in 2005/6 and from Yanou Lake in 2006/7. GDGT data were collected between 2007-2016. Samples were kept frozen at BAS, Cambridge and GDGT compounds extracted using standard procedures described in detail in Foster et al. (2016). Temperatures were produced from the GDGT compounds included in the datasets as follows:

Pearson et al. (2011) - Global calibration

MSAT = 20.9 + (98.1xGDGT-1b) - (12.0xGDGT-II) - (20.5xGDGT-III)

Foster et al. (2016) - Antarctic calibration

MSAT = 18.7 + (80.3×GDGT-Ib) - (25.3 ×GDGT-II) - (19.4×GDGT-III) + (369.9×GDGT-IIIb)

Chronology datasets:

For Fan Lake, Lead-210 (210Pb) and Caesium-137 (137Cs) dating analysis was undertaken on the upper 11 cm of the surface core using dried and homogenised samples packed into a 40-mm tube to 40 mm depth and left to stand for at least 21 days to allow 226Ra and 214Pb to reach equilibrium. Samples were measured on an Ortec J-shape ultra-low background germanium well detector and remote preamplifier. Data analysis and dating model calculations were undertaken following standard procedures as defined in Appleby (2001). We undertook Cs-137 dating but concentration levels were at or below background/detection limits meaning peaks/ages were unreliable using this method. This is important information to retain as these two measurements are independent of each other and often undertaken together to reinforce confidence in the recent (i.e., 1850-present day) chronology. However, Cs-137 in particular, and often Pb-210 levels are often below detection limits and/or sedimentation rates are too low in Antarctic lake systems for these methods to be used with confidence. Thus, the downcore sequentially-increasing Pb-210 chronology from Fan Lake is very encouraging and improves confidences in our age-depth model for the key C20th section of this record which overlaps with observational meteorological records from South Georgia. Unsupported 210Pb estimates were derived from both the constant initial concentration (CIC) and constant rate of supply (CRS) method (Appleby and Oldfield, 1978). CRS ages were used in whole core age-depth modelling. A total of 32 samples for radiocarbon dating were taken from the Fan Lake core. Calibration of terrestrial radiocarbon ages was carried out in OXCAL v.4.2 using the SHCal13 Southern Hemisphere atmosphere dataset. For post-bomb samples, absolute percentage of modern carbon (pMC) data were corrected according to 13C/12C isotopic ratios from measured pMC, where a 'modern' pMC value is defined as 100% (ad 1950 CE),and the 'present day' pMC value is defined as 107.5% (2010 CE), and calibrated using the SHCal13 SH Zone 1-2 Bomb curve in CALIBomb. As all radiocarbon age errors are less than 50 years, calibrated ages are rounded to the nearest 5 years. A master age-depth model was constructed using a combination of all 210Pb CRS ages and 32 radiocarbon ages in a Bayesian age-depth model undertaken in BACON v2.2. All ages quoted in text are weighted mean ages produced from the BACON age-depth model rounded to the nearest 10 years. Chronological data from Fan Lake were first published in Strother et al. (2017).

For Yanou Lake (YAN), 15 AMS radiocarbon (14C) ages from, in order of preference: (1) moss macrofossil layers (consisting of hand-picked fine strands of the aquatic moss Drepanocladus longifolius (Mitt.) Paris, but also occasional layers of Campylium polygamum (Schimp.) Lange & C.E.O. Jensen, and some unidentifiable/mixed species moss fragments-considered more likely to have been reworked; (2) terrestrial and/or lacustrine algae; (3) other intact macrofossils and sub-fossils, including bones (bone-collagen, where extractable); (4) other (macro)fossil fragments; (5) organic-rich bulk sediments and, near the base of each core and as a last resort...(55)

Data collection:

Instrumentation:

From Foster et al. (2016) and Roberts et al. (2017):

Data were analysed using an Acquity Xevo TQ-S (triple quadrupole with step wave; Waters Ltd.) LC-MS set up with an atmospheric pressure chemical ionisation (APCI) source (Ion saber II) operated in positive ion mode. Analytical separation was achieved using a Grace Prevail Cyano HPLC column (3μm, 150 x2.1mmi.d.) fitted with an in line filter (Waters Acquity UPLC in-line filter, 0.2μm) at 40 degC using a binary solvent gradient where eluent A was hexane and eluent B was propanol. The LC-MS settings were: source offset 50 V, capillary 1.5 KV, desolvation temperature 200 degC, cone voltage 30 V, desolvation gas (N2). Detection was achieved using selected ion monitoring (SIM) of targeted [M +H]+ions (dwell time 50ms).The target ions were m/z 1302, 1300, 1298, 1296 and 1292 for the isoGDGTs and 1050, 1048, 1046, 1036, 1034, 1032, 1022, 1020 and 1018 for the brGDGTs. Peak identification and integration was carried out using MassLynx software (version 4.1). All statistical analysis was undertaken in R 2.15.2 (R Foundation for Statistical Computing). Bayesian age-depth model and weighted mean (wmean), median ages and 95% confidence interval age ranges were constructed using BACON v. 2. and radiocarbon and Pb-210 dating analysis of both cores. Details can be found in Strother et al. (2015) and Roberts et al. (2017).

Data quality:

Reconstructed Temperature datasets:

The Pearson et al. (2011) calibration covers a temperature range from 1.5°C to 31.2°C. It doesn't perform as well at the Antarctic sites since it has only 6 samples below 5°C. This results in an overestimation of the temperature in the lower end of the calibration range. The Foster et al. (2016) focused on increasing the number of lower temperature sites and creating a new regional calibration for Antarctic lakes. The Foster et al. (2016) calibration results should be used in preference for (sub)Antarctic lake data. Note temperatures are mean summer.

For the Yanou Lake (YAN) record, whole YAN-GDGT data set has two values that are above the 5th and 95th percentile outliers (< -0.33°C and >8.61°C). These are 11.32°C and 13.84°C at 1,660 cal a BP and 3,140 cal a BP, respectively. The Fan Lake dataset (FAN) contains three values above the 95th percentile value of 12.87°C between 3,440 and 3,550 cal a BP. Note that any values greater than the 10.3°C maximum limit of the Foster et al. (2016) calibration dataset should be treated with caution. The Foster et al calibration is better suited for use in colder lakes such as Fan Lake and Yanou Lake. As a result, it reproduced the C20th observational MSAT data for Fan Lake and Yanou Lake well, and better than the Pearson et al (2011) calibration. However, it also produced some unexpectedly high temperatures for some, but not all, samples older than 2 ka in the Fan and Yanou lake reconstructions.

We are currently investigating this. The most straightforward explanation is the need for more data in the upper end of the temperature gradient in the Antarctic (Foster et al. 2016) calibration dataset. To address this we are currently working on improving and updating the Antarctic, and global, lake GDGT-temperature calibrations.

Metadata

File identifier

df50e30a-0672-461a-928e-aafafb45fd55 XML

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Hierarchy level name

dataset

Date stamp

2019-10-03

Metadata standard name

ISO 19115 Geographic Information - Metadata

Metadata standard version

ISO 19115:2003(E)

Metadata author

Organisation name	Individual name	Electronic mail address	Role
NERC EDS UK Polar Data Centre		polardatacentre@bas.ac.uk	Point of contact