Science workshop on blue blob
Margit «Convection and ventilation updates, new results» and Jonathan “How the Greenland-Scotland Ridge (GSR) shapes the Atlantic Meridional Ocean Circulation and controls low-to-high latitude heat transport”
Ice2ice DMI/NBI meeting
Please let Helle know if you have updates for the agenda.
Eystein’s presentation from Poland. «Abrupt change, future perspectives»
Science discussion possibly on:
2+2b combined: Cross model sensitivity studies NORESM and EC-Earth (plus Peter, Shuting, Stockholm)+JHC
run made over summer, science point for PI in autumn
Emilie and Kerim – Heinrich events vs DO-stadials
Agenda will be announced later.
Title: “High-resolution methane record of the RECAP ice core (Eastern Greenland) over the last climatic cycle”
Abstract: “Methane (CH4) is among the three most important greenhouse gases. Its concentration varied in the past and the only way to extract the information is to measure the past atmosphere samples trapped in the ice cores. We present the REnland ice CAP (RECAP) CH4 record covering the last glacial cycle (120 000 years).
The modern interglacial (Holocene) section (the last 11 700 years) represents the first continuous high-resolution methane record of the Northern Hemisphere and exhibits the centennial-scale variability. A possible explanation for this observation could be in the global teleconnection of the intertropical convergence zone and its influence on the monsoon activity, which in turn has an effect on the CH4 emissions for the tropical wetlands – the dominant source of methane.
During a part of the Last Glacial, we reveal that approximately 78 000 – 83 000 years ago an additional source of methane was active in the Northern Hemisphere. The environmental reconstructions suggest that it could be the boreal wetlands, exposed after the retreat of the ice sheet and the following drainage of ice-dammed lakes in the area.
As side projects, we also work on the improvement of the continuous flow analysis (CFA) technique for the gas applications – the technique used for the RECAP ice core measurements, and on the on-site CH4 measurements at the Eastern Greenland Ice core Project (EGRIP). We identify a diurnal variability of the CH4 concentration in the surface air an upper firn column, which was earlier considered as convectively mixed”.
Tid: 23. november 2018, kl. 13:00-17:00
Sted: Centre for Ice and Climate, Rockefeller Complex, Juliane Maries Vej 30, 2nd floor, room 235
Arrangør: Centre for Ice and Climate
Prof. Thomas Blunier, Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.
Ass. Prof. Anders Svensson, Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.
Ass. Prof. Giuliana Panieri, Centre for Arctic Gas Hydrate, Environment and Climate, UiT – The Arctic University of Norway.
Célia Sapart, Laboratoire de Glaciologie, Université Libre de Bruxelles.
Tid: 26. november 2018, kl. 13:00-17:00
Sted: Centre for Ice and Climate, rockefeller Complex, Juliane Maries Vej 30, 2nd floor, room 235
Arrangør: Centre for Ice and Climate
Camille Li and Andreas Born will present their newest paper “Coupled atmosphere-ice-ocean dynamics in Dansgaard-Oeschger events“ and we will have the opportunity to discuss with them. You can find the paper here; https://www.sciencedirect.com/science/article/pii/S0277379118305705
After the presentation and discussion, we will have a small Christmas event and serve you gløgg and something sweet to eat. Please indicate here if you want to join in, before Friday 30.11 at 12.
The Dansgaard-Oeschger events of the last ice age are among the best studied abrupt climate changes, yet a comprehensive explanation is still lacking. They are most pronounced in the North Atlantic, where they manifest as large temperature swings, on timescales of decades or shorter, between persistent cold (stadial) and warm (interstadial) conditions. This review examines evidence that Dansgaard-Oeschger events are an unforced or “spontaneous” oscillation of the coupled atmosphere-ice-ocean system comprising the North Atlantic, Nordic Seas and Arctic, collectively termed the Northern Seas. Insights from reanalysis data, climate model simulations, and idealized box model experiments point to the subpolar gyre as a key coupling region where vigorous wind systems encounter the southernmost extension of sea ice and the most variable currents of the North Atlantic, with connections to the deep ocean via convection. We argue that, under special conditions, these components can interact to produce Dansgaard- Oeschger events. Finding the sweet spot is a matter of understanding when the subpolar region enters a feedback loop whereby changes in wind forcing, sea ice cover, and ocean circulation amplify and sustain perturbations towards cold (ice-covered) or warm (ice-free) conditions. The resulting Dansgaard-Oeschger-like variability is seen in a handful of model simulations, including some “ugly duckling” pre-industrial simulations: these may be judged as undesirable at the outset, but ultimately show value in suggesting that current models include the necessary physics to produce abrupt climate transitions, but exhibit incorrect sensitivity to the boundary conditions. Still, glacial climates are hypothesized to favour larger, more persistent transitions due to differences in large-scale wind patterns. Simplified models and idealized experimental setups may provide a means to constrain how the critical processes act, both in isolation and in combination, to destabilize the subpolar North Atlantic.
Low-latitude climate variability during the late Quaternary and teleconnections to high latitudes
Time: Mandag 21. januar 2019, kl. 10.15
Venue: Auditorium 4, Realfagbygget
Forsker Anna Nele Meckler, Institutt for geovitenskap
Professor Haflidi Haflidason, Institutt for geovitenskap
Professor Kerim Hestnes Nisancioglu, Institutt for geovitenskap