Twentieth century warming in deep waters of the Gulf of St. Lawrence: A unique feature of the last millennium

Type Article
Date 2010-09
Language English
Author(s) Thibodeau Benoit1, de Vernal Anne1, Hillaire-Marcel Claude1, Mucci Alfonso2
Affiliation(s) 1 : Univ Quebec, Geochem & Geodynam Res Ctr, Geotop, Montreal, PQ H3C 3P8, Canada.
2 : McGill Univ, Geochem & Geodynam Res Ctr, Geotop, Dept Earth & Planetary Sci, Montreal, PQ H3A 2A7, Canada.
Source Geophysical Research Letters (0094-8276) (Amer Geophysical Union), 2010-09 , Vol. 37 , N. 17 / L1760 , P. 1-5
DOI 10.1029/2010GL044771
WOS© Times Cited 26
Note Auxiliary material for this article contains a text file with two figures and a table : http://onlinelibrary.wiley.com/doi/10.1029/2010GL044771/suppinfo
Abstract The impact of human activities on Earth's climate is still subject to debate and the pattern of a sharp recent global temperature increase contrasting with much lesser variable temperatures during preceding centuries has often been challenged, partly due to the lack of unquestionable evidence. In this paper, oxygen isotope compositions of benthic foraminifer shells recovered from sediments of the Lower St. Lawrence Estuary and the Gulf are used to reconstruct temperature changes in a water mass originating from similar to 400 m deep North Atlantic waters. The data demonstrate that the 1.7 +/- 0.3 degrees C warming measured during the last century corresponds to a delta(18)O shift of 0.4 +/- 0.05 parts per thousand, encompassing the temperature effect and related change in the isotopic composition of the corresponding water mass. In contrast, d18O values remained nearly constant over the last millennium, except for a small positive shift which we attribute to the Little Ice Age. We conclude that the 20th century warming of the incoming intermediate North Atlantic water has had no equivalent during the last thousand years.
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