SEADOG · Sea ice across Dansgaard-Oeschger events in Greenland
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2015-10-01 → 2017-09-30
- EU contribution
- €183,455
- Participants
- 1
- Scheme
- MSCA-IF-EF-RI
Lines connect the coordinator with its partners.
Results in brief
Sea ice across Dansgaard-Oeschger events in Greenland
In the Last Glacial period, the climate of the Northern Hemisphere was punctuated by abrupt millennial scale changes called Dansgaard-Oeschger (D-O) events that are clearly recorded by Greenland ice core temperature proxies. The underlying mechanism responsible for the recurring cycles of ~10°C rapid increase, followed by gradual cooling, remains uncertain. Many studies suggest that large changes in sea ice extent played a major role. Sea ice is closely linked to climate; changes in sea ice extent feedback positively on Arctic temperature—a phenomenon of great relevance to the future of Arctic sea ice given our warming climate. By combining Greenland ice core chemistry records with atmospheric chemistry transport modeling, SEADOG aimed to constrain Arctic sea ice variability across D-O events. Sea salt sodium (Na) was the focus of this work because substantial evidence suggests that the surface of the sea ice is a significant source of sea salt to the polar regions. This raises the possibility that ice core Na may be interpreted as a tracer of past sea ice conditions. Model simulations of sea salt aerosol at various Arctic sites, produced by this project, confirm the importance of the sea ice source of sea salt aerosol. For the first time, sea salt concentrations deposited at Greenland ice core sites were calculated using a global process-based model. Simulated values compared well with monthly-resolved ice core chemistry records. Based on tests conducted, we conclude that the influence of sea ice extent on year-to-year changes in Greenland ice core sea salt concentrations is minimal under present-day Arctic conditions. The majority of ice core sea salt variation is due to meteorological factors. However, ice cores from the High Arctic, away from central Greenland, offer promise for sea ice reconstruction. Adaption of atmospheric chemistry transport models for simulations of D-O events under Last Glacial climatic conditions is still ongoing.
Data: CORDIS, © European Union
Project objective
The Last Glacial climate of the Northern Hemisphere was punctuated by abrupt millennial scale changes called Dansgaard-Oeschger (DO) events, clearly recorded by Greenland ice core temperature proxies. The underlying mechanism responsible for the recurring cycles of ~10°C rapid increase, followed by gradual cooling, remains uncertain. Many studies suggest that large changes in sea ice extent played a major role in their causation. Sea ice is closely linked to climate; changes in sea ice extent feedback positively on Arctic temperature—a phenomenon of great relevance to the future of Arctic sea ice in our changing climate. This project combines Greenland ice core chemistry records with atmospheric chemistry transport modeling in order to constrain Arctic sea ice variability across DO events. Records of sea salt (Na+), and methane sulphonic acid (MSA), from four ice cores will be analysed for spatial and temporal variability across DO events. The controls on marine aerosol deposition over the Greenland Ice Sheet will be investigated using a atmospheric chemistry transport model, Cambridge p-TOMCAT, which has been successfully deployed for the Antarctic. The relative influence of sea ice and other factors e.g., meteorology, on ice core chemistry variability will be assessed using sensitivity tests that will also provide an indication of the gross sea ice changes in required to reproduce the significant sea salt changes recorded in ice cores. Furthermore, an atmospheric chemistry transport model, that can be interfaced with fully coupled ocean-atmosphere climate model output, will be optimised according to our findings. This model will be run with palaeoclimatic boundary conditions to obtain scenarios of sea ice change consistent with the ice core chemistry data. Separate tests will constrain the magnitude of sea ice retreat at the onset of DO events and the temporal evolution of sea ice conditions as climate cools from warm interstadial to cool stadial conditions.
Original text from CORDIS.
Participants
- THE CHANCELLOR MASTERS AND SCHOLARS OF THE UNIVERSITY OF CAMBRIDGE · CAMBRIDGECoordinatorUnited Kingdom
Links
- View on CORDIS
- DOI: 10.3030/658120
- https://web.archive.org/web/20160719224541/https://www.esc.cam.ac.uk/directory/R-Rhodes
- https://www.esc.cam.ac.uk/directory/R-Rhodes
Data: CORDIS, © European Union