• European Marine Science
• National Science Foundation close
• TiPES close
• EU close

Accurate estimates of the past extent of the Greenland ice sheet provide critical constraints for ice sheet models used to determine Greenland’s response to climate forcing and contribution to global sea level. Here we use a continuous ice core dust record from the Renland ice cap on the east coast of Greenland to constrain the timing of changes to the ice sheet margin and relative sea level over the last glacial cycle. During the Holocene and the previous interglacial period (Eemian) the dust record was dominated by coarse particles consistent with rock samples from central East Greenland. From the coarse particle concentration record we infer the East Greenland ice sheet margin advanced from 113.4 ± 0.4 to 111.0 ± 0.4 ka BP during the glacial onset and retreated from 12.1 ± 0.1 to 9.0 ± 0.1 ka BP during the last deglaciation. These findings constrain the possible response of the Greenland ice sheet to climate forcings. Accurate measurements of the past extent of the Greenland ice sheet are crucial to understand its response to changing climate conditions. Here, the authors present a dust record from an ice core from the east coast of Greenland to provide detailed time constraints on ice sheet advance and retreat over the last interglacials.

The last glacial period is characterized by a number of millennial climate events that have been identified in both Greenland and Antarctic ice cores and that are abrupt in Greenland climate records. The mechanisms governing this climate variability remain a puzzle that requires a precise synchronization of ice cores from the two hemispheres to be resolved. Previously, Greenland and Antarctic ice cores have been synchronized primarily via their common records of gas concentrations or isotopes from the trapped air and via cosmogenic isotopes measured on the ice. In this work, we apply ice core volcanic proxies and annual layer counting to identify large volcanic eruptions that have left a signature in both Greenland and Antarctica. Generally, no tephra is associated with those eruptions in the ice cores, so the source of the eruptions cannot be identified. Instead, we identify and match sequences of volcanic eruptions with bipolar distribution of sulfate, i.e. unique patterns of volcanic events separated by the same number of years at the two poles. Using this approach, we pinpoint 82 large bipolar volcanic eruptions throughout the second half of the last glacial period (12–60 ka). This improved ice core synchronization is applied to determine the bipolar phasing of abrupt climate change events at decadal-scale precision. In response to Greenland abrupt climatic transitions, we find a response in the Antarctic water isotope signals (δ18O and deuterium excess) that is both more immediate and more abrupt than that found with previous gas-based interpolar synchronizations, providing additional support for our volcanic framework. On average, the Antarctic bipolar seesaw climate response lags the midpoint of Greenland abrupt δ18O transitions by 122±24 years. The time difference between Antarctic signals in deuterium excess and δ18O, which likewise informs the time needed to propagate the signal as described by the theory of the bipolar seesaw but is less sensitive to synchronization errors, suggests an Antarctic δ18O lag behind Greenland of 152±37 years. These estimates are shorter than the 200 years suggested by earlier gas-based synchronizations. As before, we find variations in the timing and duration between the response at different sites and for different events suggesting an interaction of oceanic and atmospheric teleconnection patterns as well as internal climate variability.

The RECAP ice core was drilled on Renland ice cap, coastal East Greenland, in May-June 2015. This dataset presents the first complete timescale for the ice core record, based on impurity (dust and chemistry) as well as gas content measurements. The underlying dust particle and gas (CH4, d15N and d18Oair) data are presented. Strontium and Neodymium measurements of potential dust source samples collected from exposed terrain in central East Greenland are also presented. The timescale is called 'RECAP GICC05modelext Time Scale (version 1/3-2018)' and has been synchronized to the existing GICC05modelext timescale. All synchronization tiepoints are presented.

The RECAP ice core was drilled on Renland ice cap, coastal East Greenland, in May-June 2015. This dataset presents the first complete timescale for the ice core record, based on impurity (dust and chemistry) as well as gas content measurements. The underlying dust particle and gas (CH4, d15N and d18Oair) data are presented. Strontium and Neodymium measurements of potential dust source samples collected from exposed terrain in central East Greenland are also presented. The timescale is called 'RECAP GICC05modelext Time Scale (version 1/3-2018)' and has been synchronized to the existing GICC05modelext timescale. All synchronization tiepoints are presented.