Methodology:

Cores were collected in January 2012 (Elephant Island and Ardley Island) and January 2013 (Green Island). Sample collection was supported by HMS Protector and HMS Endurance. Specific core sites were selected to access the deepest and oldest records available, whilst ensuring as complete spatial coverage of the AP as possible given the sporadic locations in which moss banks grow. Cores were carefully cut and removed by hand from non-permafrost near-surface sediments and stored at -20°C. Frozen core sections were sub-sampled at 5 mm resolution using a microtome slicer.

Temporal sampling resolution is approximately one sample every 3-5 years, on average, though variability in this figure exists between sites and within cores.

Missing data values for carbon isotopes reflect depths at which it was not possible to isolate enough pure cellulose for analysis. Missing values at depth for accumulation rate (ARD3) reflect where it was not possible to get a bulk density measurement due to an air pocket within the core. Near-surface missing values for accumulation rate reflect a combination of a lack of bulk density measurements in the uppermost (unconsolidated/vegetated) samples, as well as the way that rates over time are calculated. Near-surface missing values for testates reflect the way that rates over time are calculated. Each calculated sample value includes the amount of time (as per the relevant age-depth model) since the previous sample. Since there is no previous value for the uppermost sample, it is not possible to calculate a rate over time for the top sample.

For full methodological details applied to individual samples, please see Amesbury et al. (2017).

Data quality:

See the referenced publication for further information.