Fast and slow components of interstadial warming in the North Atlantic during the last glacial

The abrupt nature of warming events recorded in Greenland ice-cores during the last glacial has generated much debate over their underlying mechanisms. Here, we present joint marine and terrestrial analyses from the Portuguese Margin, showing a succession of cold stadials and warm interstadials over the interval 35–57 ka. Heinrich stadials 4 and 5 contain considerable structure, with a short transitional phase leading to an interval of maximum cooling and aridity, followed by slowly increasing sea-surface temperatures and moisture availability. A climate model experiment reproduces the changes in western Iberia during the final part of Heinrich stadial 4 as a result of the gradual recovery of the Atlantic meridional overturning circulation. What emerges is that Greenland ice-core records do not provide a unique template for warming events, which involved the operation of both fast and slow components of the coupled atmosphere–ocean–sea-ice system, producing adjustments over a range of timescales.We thank Russell Drysdale and Eric Wolff for comments on specific aspects of the paper. Financial support was provided by Natural Environment Research Council grants NE/C514758/1 (to P.C.T., held at the University of Leeds) and NE/J00653X/1 (to D.A.H.), and Australian Research Council grant FT180100606 (to L.M.). E.C. acknowledges financial support from the ChronoClimate project, funded by the Carlsberg Foundation and MME from the Research Council of Norway and from COFUND – Marie Skłodowska-Curie Actions FP7, project numbers 274429 and 223259. B.M. acknowledges support from the CSIC Ramón y Cajal postdoctoral programme RYC-2013-14073 and LINKA20102. We wish to acknowledge use of the Ferret program for generating the maps in Fig. 7 and Supplementary Fig. 2 in this paper. Ferret is a product of NOAA’s Pacific Marine Environmental Laboratory (information is available at http://ferret.pmel.noaa.gov/Ferret/).Peer reviewe