(Table S1) Age determination of sediment core OCE326-GGC5

The Atlantic meridional overturning circulation is widely believed to affect climate. Changes in ocean circulation have been inferred from records of the deep water chemical composition derived from sedimentary nutrient proxies (Boyle and Keigwin, 1987, doi:10.1038/330035a0), but their impact on climate is difficult to assess because such reconstructions provide insufficient constraints on the rate of overturning (LeGrand and Wunsch, 1995, doi:10.1029/95PA01455). Here we report measurements of 231Pa/230Th, a kinematic proxy for the meridional overturning circulation, in a sediment core from the subtropical North Atlantic Ocean. We find that the meridional overturning was nearly, or completely, eliminated during the coldest deglacial interval in the North Atlantic region, beginning with the catastrophic iceberg discharge Heinrich event H1, 17,500 yr ago, and declined sharply but briefly into the Younger Dryas cold event, about 12,700 yr ago. Following these cold events, the 231Pa/230Th record indicates that rapid accelerations of the meridional overturning circulation were concurrent with the two strongest regional warming events during deglaciation. These results confirm the significance of variations in the rate of the Atlantic meridional overturning circulation for abrupt climate changes.

Age determination of sediment core PTA02-04 from Laguna Potrok Aike, Patagonia (Table 1)

The volcanogenic lake Laguna Potrok Aike, Santa Cruz, Argentina, reveals an unprecedented continuous high resolution climatic record for the steppe regions of southern Patagonia. With the applied multi-proxy approach rapid climatic changes before the turn of the first millennium were detected followed by medieval droughts which are intersected by moist and/or cold periods of varying durations and intensities. The 'total inorganic carbon' content was identified as a sensitive lake level indicator. This proxy suggests that during the late Middle Ages (ca. AD 1230-1410) the lake level was rather low representing a signal of the 'Medieval Climate Anomaly' in southeastern Patagonia. At the beginning of the 'Little Ice Age' the lake level rose considerably staying on a high level during the whole period. Subsequently, the lake level lowered again in the course of the 20th century.

Palynological record and radiocarbon dates for sediment core T89-16, Congo River mouth

We present a high-resolution reconstruction of tropical palaeoenvironmental changes for the last deglacial transition (18 to 9 cal. kyr BP) based on integrated oceanic and terrestrial proxies from a Congo fan core. Pollen, grass cuticle, Pediastrum and dinoflagellate cyst fluxes, sedimentation rates and planktonic foraminiferal d18O ratios, uK37 sea-surface temperature and alkane/alkenone ratio data highlight a series of abrupt changes in Congo River palaeodischarge. A major discharge pulse is registered at around 13.0 cal. kyr BP which we attribute to latitudinal migration of the Intertropical Convergence Zone (ITCZ) during deglaciation. The data indicate abrupt and short-lived changes in the equatorial precipitation regime within a system of monsoonal dynamics forced by precessional cycles. The phases of enhanced Congo discharge stimulated river-induced upwelling and enhanced productivity in the adjacent ocean.