02473nas a2200277   4500000000100000000000100001008004100002653001800043653000900061653002100070653001500091653002700106100001600133700001900149700001200168700001600180700002100196700002100217700002200238245015100260856007100411300001200482490000800494520167900502020001402181       2010                            d10a(231Pa/230Th)10aAMOC10aice-sheet growth10ainsolation10aLast Glacial Inception1 aAbel Guihou1 aSylvain Pichat1 aS\ Nave1 aAline Govin1 aLaurent Labeyrie1 aElisabeth Michel1 aClaire Waelbroeck00aLate slowdown of the Atlantic Meridional Overturning Circulation during the Last Glacial Inception: New constraints from sedimentary (231Pa/230Th)  uhttp://www.sciencedirect.com/science/article/pii/S0012821X09007079  a520-5290 v2893 aOur study gives new constraints on the response of Atlantic Meridional Overturning Circulation (AMOC) export to various forcings during the Last Glacial Inception. The decay corrected excess sedimentary (231Pa/230Th) activity ratio (hereafter referred to as (Pa/Th)) has been measured over that period in two deep cores from the Western (SU90-11, 44\textdegree04 N, 40\textdegree01 W, 3645 m) and Eastern (MD01-2446, 39\textdegree03 N, 12\textdegree37 W, 3547 m) basins of the North Atlantic. Both records display significant changes despite the relatively short half-life of 231Pa (\~ 32 kyr) compared to the period we investigate. The (Pa/Th) variability does not correlate to changes in local opal flux normalized to 230Th. Moreover, the (Pa/Th) profiles display a high degree of coherency with indirect proxies of AMOC activity such as the benthic foraminifera δ13C and the mid-latitude summer Sea Surface Temperature in nearby reference cores. These additional pieces of evidence support our interpretation of the (Pa/Th) as reflecting AMOC export. The (Pa/Th) repeatedly underwent rapid changes during the Last Glacial Inception associated with the extension of ice rafted detritus in the North Atlantic, highlighting the control of ice-sheet dynamics through freshwater forcing on AMOC export. AMOC export remains large during periods of ice-sheet growth and its decreases lag the Northern Hemisphere summer insolation forcing. AMOC modulation appears driven by ice-sheet dynamics, itself driven by the seasonal insolation gradient between low and high Northern Hemisphere latitudes and the associated intensity of the meridional oceanic and atmospheric circulation.  a0012-821X