Changes in ocean dynamics in the northern North Atlantic affect the thermohaline circulation that controls global climate. During glacial and deglaciation periods these dynamics are enhanced due to large variations in the surface ocean density caused by changes in glacier volumes. During full interglacial conditions, the dominant role of the northern North Atlantic on global climate is limited due to the reduced discharge of freshwater to the ocean, causing other regional dynamics to gain importance. Here we present a speleothem δ18O record from the Iberian Peninsula that supports that the northern North Atlantic and tropical North Atlantic were both source regions of millennial climate oscillations during the Holocene. The speleothem δ18O signal records millennial time-scale changes in the hydrological cycle as a result of persistent anomalies of the Gulf Stream–North Atlantic Current dynamics. In addition, the speleothem δ18O record shows synchronous variability with records from the eastern Pacific region though the entire Holocene, whereas records from western Pacific region have limited or no correlation beyond periods of major instability of the northern North Atlantic. The discontinuous climate connection among the studied records is the result of different mechanisms affecting the climate system that originated in distant regions. We suggest that two regions, the tropical North Atlantic and northern North Atlantic, alternate their dominance as source regions causing millennial climate anomalies in large planetary regions. The duration of these persistent climate changes and the extension of the regions affected depend on the region triggering the anomaly because different mechanisms affecting the climate system are involved.

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Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.