气候变化领域集成服务门户(CCPortal): Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean

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DOI	10.1016/j.quascirev.2020.106635
	Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean
	Parker W.G.; Yanes Y.; Hernández E.M.; Surge D.
发表日期	2020
ISSN	0277-3791
卷号	249
英文摘要	The Medieval Climate Anomaly (MCA; 900–1300 AD) was the most recent period of pre-industrial climatic warming in the northern hemisphere, and thus estimations of MCA signals can illuminate possible impacts of anthropogenic climate change. Current high-resolution MCA climate signals are restricted to mid- and high-latitude regions, which confounds inferences of how the MCA impacted some global/hemispheric climate mechanisms (e.g. North Atlantic Oscillation; NAO). To address this knowledge gap, we estimate seasonally-resolved sea surface temperatures (SSTs) from the oxygen isotope composition (δ18O) of serially sampled Phorcus atratus shells from archaeological sites spanning the MCA in the Canary Islands. Twelve archaeological and six modern P. atratus shells were analyzed, and archaeological shells were dated using carbonate-target radiocarbon dating. SSTs were estimated using the published aragonite-water equilibrium fractionation equation. Modern shells showed a mean SST of 20.0 ± 1.5 °C, with a seasonal amplitude of 5.3 ± 0.9 °C. Archaeological shells exhibited a mean SST of 18.2 ± 0.7 °C, with a mean seasonal amplitude of 5.5 ± 1.0 °C. Thus, shells that span the MCA in the Canary Islands recorded SSTs that were significantly cooler than the modern (P <.05), contrasting with warming estimates and model predictions elsewhere in the Northern Hemisphere. We propose that the observed cooling resulted from increased upwelling in NW Africa due to a strengthening of the prevailing westerlies and coastal winds along the African shoreline. The intensified upwelling scenario during the MCA is partially supported by in-situ carbon isotope data (δ13C) retrieved from the archaeological shells, which was compared to the δ13C values of modern shells and dissolved inorganic carbon in the ambient seawater. These results are consistent with other low-latitude temperature/precipitation anomalies associated with a positive NAO mode, suggesting a transition to a positive NAO index during the middle and late MCA that possibly extended later into the 13th century AD. © 2020 Elsevier Ltd
英文关键词	Holocene; Medieval climate anomaly; North Atlantic; Paleoclimatology; Phorcus atratus; Stable isotopes
语种	英语
scopus关键词	Atmospheric pressure; Carbon; Climate change; Isotopes; Shells (structures); Surface waters; Tropics; Anthropogenic climate changes; Dissolved inorganic carbon; Eastern north atlantic oceans; Equilibrium fractionations; Medieval climate anomalies; North Atlantic oscillations; Oxygen isotope composition; Sea surface temperatures; Oceanography; anthropogenic effect; carbon isotope; climate change; Medieval; Northern Hemisphere; radiocarbon dating; sea surface temperature; shell; upwelling; Atlantic Ocean; Atlantic Ocean (North); Canary Islands; Spain
来源期刊	Quaternary Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151252
作者单位	University of Cincinnati, Cincinnati, OH, United States; Universidad de La Laguna, San Cristobal de La LagunaCanary Islands, Spain; University of North Carolina, Chapel Hill, NC, United States
推荐引用方式 GB/T 7714	Parker W.G.,Yanes Y.,Hernández E.M.,et al. Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean[J],2020,249.
APA	Parker W.G.,Yanes Y.,Hernández E.M.,&Surge D..(2020).Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean.Quaternary Science Reviews,249.
MLA	Parker W.G.,et al."Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean".Quaternary Science Reviews 249(2020).