Antarctic Ice Sheet Response to Past Warmer than Present climates

Informations projet

ANTICE

N° de convention de subvention: 841980

DOI

10.3030/841980

Projet clôturé

Date de signature de la CE 8 Avril 2019

Date de début 16 Mai 2019

Date de fin 15 Mai 2022

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 259 398,72

Contribution de l’UE

€ 259 398,72

Coordonné par

AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain

Periodic Reporting for period 1 - ANTICE (Antarctic Ice Sheet Response to Past Warmer than Present climates)

Période du rapport: 2019-05-16 au 2022-05-15

Résumé du contexte et des objectifs généraux du projet

Changes in the Earth climate system caused by natural/anthropogenic drivers (e.g. CO2) are communicated to Antarctica by oceanic and atmospheric processes, and influence the polar atmosphere, the Southern Ocean (SO), the Antarctic cryosphere (ice sheet/sea ice), and the biosphere. The Antarctic ice sheet is losing mass at an accelerating rate. Geological records of past deglaciations are key to understanding cryosphere-oceanic interactions leading to and during past ice sheet margin retreats, thus informing about mechanisms, rates and magnitudes of sea level rise in future warming scenarios.
The overall objective of the ANTICE project is to understand the processes, drivers, and when possible rates of marine-based East Antarctic ice sheet loss during past glacial terminations, and to assess their impact on the phytoplankton. To fulfill this objective, we study sediment records recovered from the east Antarctic Wilkes Land margin during the Integrated Ocean Program Expedition 318. We focus on two past deglaciation periods taking place under a range of climatic and oceanic conditions within the range of current to near future conditions projected by the IPCC AR5 and AR6: (1) the Holocene deglaciation (~10.000 yr) (WP1), and (2) two Pliocene deglaciations (~ 3.6 and 4.2 My) (WP2). We expect the results from this research will have a large impact in increasing our now limited understanding of the response of the Southern Ocean and the marine-based East Antarctic Ice sheet (EAIS) to ongoing climate change. Moreover, the results can be used to validate and test current models of ocean and ice sheet behaviour used by the Intergovernmental Panel on Climate Change (IPCC).
Conclusion WP1: sedimentological patterns of the last deglaciation in East Antarctica have been defined, linking oceanic and ecosystem changes and constraining the timing of the deglaciation.
Conclusion WP2: sedimentological and paleoenvironmental changes are differentiated in cold (glacial) vs warm (interglacial) Pliocene sediments in the overall warm Pliocene period (3-5 Ma) with similar CO2 concentrations than today.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

Holocene deglaciation work (WP1) includes: 1) ice sheet-ocean processes during the transition from a subglacial to a seasonal-open marine environment; and 2) develop a chronological context for ice sheet-ocean interactions and changing paleoenvironments. Results of WP1: sedimentological model for the Holocene deglaciation (~24kyr-9 kyr), characterized the spatial and temporal changes in the marine based EAIS, linking these changes in oceanographic conditions and biota adaptation. Results have been disseminated in congresses and are now in revision by authors to be submitted in an Open Access journal. Pliocene interglacials work (WP2) to characterize changing environmental and biota conditions during the terminations. Results of WP2 (in progress): characterize the different sedimentological, biological and geochemical (oceanic) conditions during Pliocene “warmer-than-present” terminations. We are able to characterize for the first time ocean and phytoplankton responses to changing conditions within each warm interval. First results were presented in a congress and will be published in an Open Access journal.
Participation in the Tasmandrake Spanish Powell2020 Antarctic cruise. Water samples were obtained to characterize physical-biochemical-ecosystem processes, key to calibrate the indicators in sediment cores used to interpret past environments. Publications are being prepared.
Most analyses have been conducted with the analytical techniques proposed in the project, despite of some analytical delays and secondment cancellations caused by the COVID-19:
A Data Management Plan was submitted on time, as deliverable, in November 2019; Analysis of CT-scan data with ImageJ/FIJI software; Microfossil analyses; Grain size, biogenic opal and smear slides samples at the IACT; HRSEM analysis at CIC-UGR; Grain size analysis at the University of Bordeaux and CIC; Interpretation/integration of all data at the IACT; Collaboration with national/ international laboratories include: University of Bordeaux (grain size), University Salamanca (diatoms), University of Wellington (ramped pyrolysis dating), ETH (laser dating), Stanford University (radiocarbon dating), University of Salamanca and CIC (UGR) (radiocarbon dating), and University of Bremen (Biogenic opal); Short visits to Universities of Bordeaux, Salamanca and IGME (Madrid) were done to work with collaborators; International congresses: three online due to COVID-19 (SCAR 2020, EGU 2021 and EGU 2022) and one in person in 2021 (SGE, Vitoria, Spain). Abstracts published in Open Access; Preparation of Open Access WP1 and WP2 publications; Reviewer for the Journal NHESS; Participation in IACT activities (e.g. virtual and in person project meetings, mentoring PhD students; preparation of expedition logistics, etc); Memberships: POLARCSIC, Academia Net: SNSF, ICEPRO (CSIC), EGU 2021/2022, and SCAR INSTANT; Outreach/educational activities: talks, workshops, blog in newspaper, radio, social media, and educational materials: co-author in a book chapter (CSIC editorial), videos, flyers, photo exhibition; Training courses: IMAGEJ/FIJI software, the Managing Biodiversity data online course in Polar region (2021) and Database ConCiencia (CSIC);Seminars and informative workshops: Tasmandrake (2019), Polar Committee (2019), ICEPRO (2021), Inquamare Workshop (2021), and PTI Polar CSIC (2022).

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The ultra-high resolution deglaciation record recovered by Expedition 318 allows for the development of a sedimentological model of ice sheet retreat of unprecedented detail. In addition to documenting ice sheet-ocean-biotic changes taking place as environments changed from subglacial to open marine forced by the warming that followed the Last Glacial Maximum, we interpret a non-linear retreat. These results are expected to be of high-impact and have the potential to be policy-relevant as IPCC projections of future sea level rise account for a linear retreat. These innovative findings can shed light on the recent to present Southern Ocean dynamics in response to the ongoing global warming, which is one of the main issues in Earth nowadays.
Project results derived from the study of the Pliocene sediment section provide with a novel characterization of the oceanic and phytoplankton changes that take place during glacial-interglacial terminations, within the warm intervals and at the end of the interglacial periods of the early warm Pliocene (5-3 Ma). These findings are key to understand the future response of the Southern Ocean and biota under CO2 concentrations similar to present and elevated sea surface temperatures similar to those previously reported for the early Pliocene in the SO (5ºC above pre-industrial), which expected in the near future.
The results of this action thus have a high social impact, addressing high priority questions in Antarctica and the Southern Ocean research as defined by the: 1) Scientific Committee for Antarctic Research (SCAR) INSTANT Scientific Research Programme; and 2) Horizon 2020 EU PolarNet.
The implementation of the project enhances the options to reach excellence in an scientific career, increasing the options for future tenure track positions.

3D CT Scan image of Holocene Sediments with Ice Rafted Debris (IRD) from Site U1357A