Ocean mixing and ice-sheet control of seawater 234U/238U during the last deglaciation by Tianyu Chen, Laura F. Robinson, Matthew P. Beasley, Louis M. Claxton, Morten B. Andersen, Lauren J. Gregoire, Jemma Wadham, Daniel J. Fornari, and Karen S. Harpp Science Volume 354(6312):626-629 November 4, 2016 Published by AAAS

Fig. 1 Seawater δ234U evolution over the past 30 ky, reconstructed from corals. Seawater δ234U evolution over the past 30 ky, reconstructed from corals. (A) Compilation of published coral initial δ234U (δ234Ui) within the range of 135 to 155‰ and with 2σ errors < 3‰ (19). Data outside of this range have been truncated. (B) Low-latitude North Atlantic records with ±2σ confidence lines (black; the green line shows the mean). Also shown are the initial δ234U values for the low-latitude Pacific, reconstructed from Galápagos deep-sea corals (the gold line shows the mean, with the dotted section highlighting the data gap in HS1). One Galápagos coral data point from the B-A with an initial δ234U higher than 155‰ has likely experienced diagenesis and is not shown (19). Black dashed lines mark the modern seawater signature. Tianyu Chen et al. Science 2016;354:626-629 Published by AAAS

Fig. 2 Seawater δ234U evolution compared with other climate records. Seawater δ234U evolution compared with other climate records. (A) Modeled retreat rate of the Northern Hemisphere (NH) and Southern Hemisphere (SH) ice sheets (33). (B) Modeled basal melting rate of the North American ice sheets (28) and ice discharge of the Laurentide Ice Sheet (29). (C) 231Pa/230Th from North Atlantic deep sediment cores (21, 23). (D) Sea-level history (34). (E) Our reconstructed δ234U evolution in the upper Atlantic and Pacific. Green solid line, Atlantic mean; green dashed line, Atlantic 2σ error; gold line, Pacific mean (dotting, HS1 data gap); gold shading, estimated range of Pacific δ234U. black dotted line, modern seawater δ234U; Gt, gigaton; y, year. Tianyu Chen et al. Science 2016;354:626-629 Published by AAAS

Fig. 3 Sensitivity experiment assessing the response of seawater δ234U to ocean circulation and external inputs. Sensitivity experiment assessing the response of seawater δ234U to ocean circulation and external inputs. (A) Effect of ocean mixing slowdown alone (sv, sverdrup). (B) Effect of variable δ234U in inputs to the upper Atlantic, applying a 50% reduction of the glacial exchange flux during HS1. The area between the dashed-dotted curves is the range of low-latitude Atlantic δ234U. External U fluxes through time in both experiments are kept at the modern inputs. The spectrum of colors denotes different experiments (solid lines, upper Atlantic; dashed lines, other ocean). Further details are in (19). Tianyu Chen et al. Science 2016;354:626-629 Published by AAAS