High-resolution climate reconstructions from the Labrador Sea area, Part I: Validation of the sedimentary sea ice proxy record against observational data
Abstract
Given the current debate on the contributions of natural processes and anthropogenic emissions to the present climate warming, which is greatly amplified in the Arctic, it is crucial to obtain a detailed account of long-term natural climate variations and their controlling factors. The aim of this study is to reconstruct Late Holocene variability in regional sea ice extent and sea surface temperatures (SST) in the Labrador Sea area using high-resolution marine sediment records. The study area is of particular climatological importance, since meltwater from sea ice and icebergs entrained by the Labrador Current directly affects the formation of North Atlantic Deep Water, which presently drives the redistribution of heat between the hemispheres. The first part of the study, presented here, consists of two short core records covering the last ca. 150 years, for most of which air and sea surface temperatures and sea ice observations are available. The study sites are located just north and south of Newfoundland, respectively. These short cores were analysed for IP25, a novel chemical tracer for the presence of seasonal sea ice, and alkenones, which are well-established as a proxy for SST. IP25 has previously been applied to produce records both in the Canadian Arctic and east of Greenland in the Fram Strait and North Icelandic Shelf area over millenial time scales. Studies enabling the comparison with climate-related modern observations are still required to further establish this highly promising proxy.The results show 1) significantly higher IP25 concentrations north of Newfoundland, which is consistent with modern sea-ice observations, 2) a good correlation between IP25 and alkenone data, particularly for the northern site, 3) an overall good agreement between our proxy data and measured air and sea surface temperature data and local and regional sea ice extent. Furthermore, the general trends in these proxy records can also be correlated to the North Atlantic Oscillation, with a positive NAO indicating colder conditions and more sea ice in the area. These results are encouraging for the second part of the study, which reconstructs IP25 and alkenones over the past ca. 5000 years at these sites in order to shed light on longer-term trends in sea ice and SST in this climatically sensitive area.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMPP31A1842W
- Keywords:
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- 4900 PALEOCEANOGRAPHY;
- 4924 PALEOCEANOGRAPHY / Geochemical tracers;
- 4950 PALEOCEANOGRAPHY / Paleoecology