100 nests in designated Adelie and Chinstrap penguin colonies are marked and then regularly monitored. Data are collected on when eggs are laid in each nest, when they hatch, when eggs or chicks are lost, and when chicks become unguarded. Data exist from 1996 onwards. For Adelie penguins, 100 nests in a colony designated A41 was monitored between 1996 and 2002, from 2003 onwards 100 nests in a colony designated A39 were monitored. For Chinstrap penguins, 100 nests in a colony designated A69 were monitored between 1996 and 2015, from 2016 onwards, 100 nests in a colony designated C66 were monitored. No data were collected in the 1997-98, 1999-2000 and 2010-2011 seasons. To calculate the annual hatching date a binomial model was fitted using the proportion of nests containing one or more chicks as the response variable and the date in days after 1 Oct as the explanatory variable. This model was fitted for each species and year separately. The dose.p function in the MASS package in R was used to derive the day when 50% of nests contained one or more chicks to produce the mean hatching date for each species-year combination. Mean laying dates were back-calculated from the mean hatching dates by subtracting the average incubation periods for each species (35 days for Adelies and 36.4 days for chinstraps, which are relatively constant between years). This has been calculated for data from 1996 to 2016.

100 nests in designated Adelie and Chinstrap penguin colonies are marked and then regularly monitored. Data are collected on when eggs are laid in each nest, when they hatch, when eggs or chicks are lost, and when chicks become unguarded. Data exist from 1996 onwards. For Adelie penguins, 100 nests in a colony designated A41 was monitored between 1996 and 2002, from 2003 onwards 100 nests in a colony designated A39 were monitored. For Chinstrap penguins, 100 nests in a colony designated A69 were monitored between 1996 and 2015, from 2016 onwards, 100 nests in a colony designated C66 were monitored. No data were collected in the 1997-98, 1999-2000 and 2010-2011 seasons. To calculate the annual hatching date a binomial model was fitted using the proportion of nests containing one or more chicks as the response variable and the date in days after 1 Oct as the explanatory variable. This model was fitted for each species and year separately. The dose.p function in the MASS package in R was used to derive the day when 50% of nests contained one or more chicks to produce the mean hatching date for each species-year combination. Mean laying dates were back-calculated from the mean hatching dates by subtracting the average incubation periods for each species (35 days for Adelies and 36.4 days for chinstraps, which are relatively constant between years). This has been calculated for data from 1996 to 2016.

The chronology of Gentoo penguins on Bird Island, South Georgia has been monitored since 1988 (no data for 1989-90 or 1990-91). 30 nests are marked in the colony at Square Pond, and 40 in the Johnson Beach colony. Regular checks are made to record when eggs are laid and the peak laying date (when 75% of nests have eggs) is calculated. This work was funded by Natural Environment Research Council (UK) core funding to the British Antarctic Survey.

We present the age scales for three Antarctic Peninsula (AP) ice cores: Palmer, Rendezvous, and Jurassic. The three age scales are all from intermediate-depth cores, in the 133-141 m depth range. The Palmer age scale covers 390 years, 1621-2011 C.E., and is from one of the oldest AP cores. Rendezvous and Jurassic are from lower elevation high-snow accumulation sites and therefore cover shorter intervals, 1843-2011 C.E. and 1874-2011 C.E., respectively. The Palmer, Rendezvous, and Jurassic cores were all drilled in November-December 2012 using the British Antarctic Survey (BAS) electromechanical dry drill (without drill fluid). Water isotopes and the chemical species used to establish the age scales were measured in the ice core labs at BAS (Cambridge, UK) using Continuous Flow Analysis (CFA) or from melted discrete cut ice samples. The annual-layer markers for dating of the cores were primarily determined using nssSO4 and H2O2 summer peaks, with d18O and MSA as additional support. This research effort was carried out by the BAS Ice Core group and the established age scales will provide the foundation for multiple upcoming projects. The ice core drilling and analysis was funded by the British Antarctic Survey, Natural Environment Research Council (NERC, Cambridge, UK), part of UK research and innovation and NERC grant [NE/J020710/1]. Palmer analysis was funded by Haus der Kulturen der Welt (HKW, Berlin, Germany), in collaboration with the Anthropocene working group (AWG).

Geological samples collected during the 2010-11 field season from James Ross Island, northeast Antarctic Peninsula.