Mg/Ca ratios in coralline algae record northwest Atlantic temperature variations and North Atlantic Oscillation relationships.

Gamboa, G., Halfar, J., Hetzinger, Steffen, Adey, W., Zack, T., Kunz, B. and Jacob, D. E. (2010) Mg/Ca ratios in coralline algae record northwest Atlantic temperature variations and North Atlantic Oscillation relationships. Open Access Journal of Geophysical Research: Oceans, 115 (C12). C12044. DOI 10.1029/2010JC006262.

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Abstract

Climate variability in the North Atlantic has been linked in part to the North Atlantic
Oscillation (NAO). The NAO influences marine ecosystems in the northwestern Atlantic
and transport variability of the cold Labrador Current. Understanding historic patterns
of NAO variability requires long‐term and high‐resolution climate records that are not
available from instrumental data. Here we present the first century‐scale proxy record of
sea surface temperature (SST) variability from the Newfoundland shelf, a region from which
other annual‐resolution shallow marine proxies are unavailable. The 116 year record
was obtained from three sites along the eastern Newfoundland shelf using laser ablation
inductively coupled mass spectrometry–determined Mg/Ca ratios in the crustose coralline
alga Clathromorphum compactum. The alga is characterized by a high Mg‐calcite skeleton
exhibiting annual growth increments and a century‐scale lifespan. Results indicate positive
correlations between interannual variations in Mg/Ca ratios and both station‐based and
gridded instrumental SST. In addition, the record shows high spatial correlations to SST
across the Newfoundland shelf and the Gulf of St. Lawrence. Before 1950 the Mg/Ca
proxy record reveals significant departures from gridded temperature records. While the
Newfoundland shelf is generally considered a region of negative correlations to the NAO, the
algal time series as well as a recent modeling study suggest a variable negative relationship
with the NAO which is strongest after ∼1960 and before the mid‐1930s.

Document Type: Article
Keywords: Climatology; Biogeochemistry; Newfoundland; Clathromorphum compactum; North Atlantic; Oscillation; NAO; ; SST; marine proxy
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2010JC006262
ISSN: 2169-9275
Date Deposited: 20 Dec 2010 09:42
Last Modified: 25 Apr 2018 09:11
URI: http://oceanrep.geomar.de/id/eprint/10597

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