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Climate of the last millennium at the southern pole of the North Atlantic Oscillation: an inner-shelf sediment record of flooding and upwelling

2011; Inter-Research Science Center; Volume: 48; Issue: 2 Linguagem: Inglês

10.3354/cr01010

1616-1572

Fatima F Abrantes, Teresa Rodrigues, B Montanari, Célia Santos, L Witt, C. Lopes, Antje H L Voelker,

Coastal wetland ecosystem dynamics

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 48:261-280 (2011) - DOI: https://doi.org/10.3354/cr01010 Contribution to the CR Special: 'Regional climate change in the NW Iberian Peninsula' Climate of the last millennium at the southern pole of the North Atlantic Oscillation: an inner-shelf sediment record of flooding and upwelling F. Abrantes1,2,*, T. Rodrigues1,2, B. Montanari1, C. Santos1,2, L. Witt3, C. Lopes1, 2, A. H. L. Voelker1, 2 1Laboratório Nacional de Energia e Geologia (LNEG), Unidade de Geologia Marinha, Apartado 7586 2721-866 Amadora, Portugal 2Centro de Investigação Marinha e Ambiental (CIMAR), 4050-123 Porto, Portugal 3Pacific Fisheries Environmental Laboratory, Pacific Grove, California 93950-2097, USA *Email: fabrantes@softhome.net ABSTRACT: Continental and marine conditions during the last millennium off Porto, Portugal (the southern pole of the North Atlantic Oscillation, NAO), are reconstructed from a sediment archive through a high-resolution multiproxy study and instrumental evidence. Results show multidecadal variability and sea surface temperatures (SSTs) that correlate well with previously published land- and sea-based Northern Hemisphere temperature records, and appear to be responding to long-term solar insolation variability. Precipitation was negatively correlated with the NAO, whereas strong flooding events occured at times of marked climate cooling (AD 1100−1150 and 1400−1470) and transitions in solar activity. AD 1850 marks a major shift in the phytoplankton community associated with a decoupling of δ18O records of 3 planktonic foraminifera species. These changes are interpreted as a response to a reduction in the summer and/or annual upwelling and more frequent fall−winter upwelling-like events. This shift's coincidence with a decrease in SST and the increase in coherence between our data and the Atlantic Multidecadal Oscillation (AMO) confirms the connection of the upwelling variability to the North Atlantic Ocean's surface and thermohaline circulation on a decadal scale. The disappearance of this agreement between the AMO and our records beyond AD 1850 and its coincidence with the beginning of the recent rise in atmospheric CO2 supports the hypothesis of a strong anthropogenic effect on the last ~150 yr of the climate record. Furthermore, it raises an important question of the use of instrumental records as the sole calibration data set for climate reconstructions, as these may not provide the best analogue for climate beyond AD 1730. KEY WORDS: Climate · Last millennium · NAO · Sediment record · Precipitation · Flooding · Upwelling · Portugal · AMO · Gulf Stream Full text in pdf format Supplementary material PreviousNextCite this article as: Abrantes F, Rodrigues T, Montanari B, Santos C, Witt L, Lopes C, Voelker AHL (2011) Climate of the last millennium at the southern pole of the North Atlantic Oscillation: an inner-shelf sediment record of flooding and upwelling. Clim Res 48:261-280. https://doi.org/10.3354/cr01010 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 48, No. 2-3. Online publication date: August 30, 2011 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2011 Inter-Research.