Change search
ReferencesLink to record
Permanent link

Direct link
Precise timing of the first drainage of the Baltic Ice Lake from Swedish glacial-varve chronologies
Stockholm University, Faculty of Science, Department of Geological Sciences.
Stockholm University, Faculty of Science, Department of Geological Sciences.
Show others and affiliations
(English)In: Article in journal (Refereed) In press
Abstract

Glacial varves can give significant insights into recession and melting rates of decaying ice sheets. Moreover, varve chronologies can provide an independent means of comparison to other annually resolved climatic archives, which ultimately help to assess the timing and response of an ice sheet to changes across rapid climate transitions. Here we report a composite 1257-year long varve chronology from south-eastern Sweden spanning the regional late Allerød-late Younger Dryas pollen zone. The chronology was correlated to the Greenland Ice Core Chronology 2005 using the time-synchronous Vedde Ash volcanic marker, which can be found in both successions. For the first time, this enables secure placement of the Lateglacial Swedish varve chronology in absolute time. Geochemical analysis from new varve successions indicate a marked change in sedimentation regime accompanied by an interruption of ice-rafted debris deposition synchronous with the onset of Greenland Stadial 1 (GS-1; 12 846 years before 1950 AD). With the support of a simple ice flow/calving model, we suggest that slowdown of sediment transfer can be explained by ice-sheet margin stabilisation/advance in response to a significant drop of the Baltic Ice Lake level. A reassessment of chronological evidence from central-western and southern Sweden further supports the hypothesis of synchronicity between the first (penultimate) catastrophic drainage of the Baltic Ice Lake and the start of GS-1 in Greenland ice cores. Our results may therefore provide the first chronologically robust evidence linking continental meltwater forcing to rapid atmosphere-ocean circulation changes in the North Atlantic.

National Category
Earth and Related Environmental Sciences
Research subject
Marine Geology
Identifiers
URN: urn:nbn:se:su:diva-126156OAI: oai:DiVA.org:su-126156DiVA: diva2:897461
Available from: 2016-01-25 Created: 2016-01-25 Last updated: 2016-03-21
In thesis
1. Deglacial impact of the Scandinavian Ice Sheet on the North Atlantic climate system
Open this publication in new window or tab >>Deglacial impact of the Scandinavian Ice Sheet on the North Atlantic climate system
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The long warming transition from the Last Ice Age into the present Interglacial period, the last deglaciation, holds the key to our understanding of future abrupt climate change. In the last decades, a great effort has been put into deciphering the linkage between freshwater fluxes from melting ice sheets and rapid shifts in global ocean-atmospheric circulation that characterized this puzzling climate period. In particular, the regional expressions of climate change in response to freshwater forcing are still largely unresolved.

This projects aims at evaluating the environmental, hydro-climatic and oceanographic response in the Eastern North Atlantic domain to freshwater fluxes from the Scandinavian Ice Sheet during the last deglaciation (~19,000-11,000 years ago). The results presented in this thesis involve an overview of the regional representations of climate change across rapid climatic transitions and provide the groundwork to better understand spatial and temporal propagations of past atmospheric and ocean perturbations.

Specifically, this thesis comprises i) a comparison of pollenstratigraphic records from densely 14C dated lake sediment sequences, which provides insight into the regional sensitivity of North European vegetation to freshwater forcing in the Nordic Seas around the onset of the Younger Dryas stadial (~12,900 years ago); ii) a reconstruction of North European hydro-climate, which, together with transient climate simulations, shed light on the mechanisms and regionality of climate shortly prior to the transition into the Younger Dryas stadial; iii) studies of a ~1250-year long glacial varve chronology, which provides an accurate timing for the sudden drainage of proglacial freshwater stored in the former ice-dammed Baltic Ice Lake into the North Atlantic Ocean; iv) a 5000-year long terrestrial-marine reconstruction of Eastern North Atlantic hydro-climate and oceanographic changes that clarifies the hitherto elusive relationship between freshwater forcing and the transient behaviour of the North Atlantic overturning circulation system. The results presented in this thesis provide new important temporal constraints on the events that punctuated the last deglaciation in Northern Europe, and give a clearer understanding of the ocean – atmosphere – ice-sheet feedbacks that were at work in the North Atlantic. This increases our understanding of how the Earth climate system functions in more extreme situations.

Place, publisher, year, edition, pages
Stockholm: Department of Geological Sciences, 2016
Series
, Meddelanden från Stockholms universitets institution för geologiska vetenskaper, ISSN 1101-1599 ; 362
Keyword
climate, North Atlantic, last deglaciation, isotope geochemistry, chronology, climate modeling
National Category
Earth and Related Environmental Sciences
Research subject
Marine Geology
Identifiers
urn:nbn:se:su:diva-128147 (URN)ISBN 978-91-7649-368-7 (ISBN)
Public defence
2016-05-13, De Geersalen, Geovetenskapens hus, Svante Arrenhius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.

Available from: 2016-04-20 Created: 2016-03-21 Last updated: 2016-04-08Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Muschitiello, FrancescoGreenwood, Sarah L.Wohlfarth, Barbara
By organisation
Department of Geological Sciences
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 75 hits
ReferencesLink to record
Permanent link

Direct link