Lake N3 I´2Haq has a >100a€° range during the past 8 kyr, larger than the range of modern seasonal I´2Hprecip in Disko Bugt (Figures 1 and 2a). We interpret these large changes in I´2Haq to indicate changes in precipitation sea- sonality, with Arctic moisture sources contributing to the exceptionally low I´2H values. The magnitude and direc- tion of I´2Haq changes cannot be explained by changes in terrestrial plant contributions of C24 n-alkanoic acids, by Holocene temperature change, or by lake water residence time (Figures S6 and S7 in the supporting information).Lake N3 I´2Haq decreased steadily from !190 to !300a€° from 7.5 to 6 ka, in step with declining sea ice in Disko Bugt (Figures 2a and 2b) [Ouellet-Bernier et al., 2014]. Lake N3 I´2Haq remained low during the middle Holocene, synchronous with minimum regional sea ice. The Labrador Sea, an important moisture source region for wes- tern Greenland [Sodemann et al., 2008], had minimum sea ice cover from 6.5 to 3.5 ka (Figure 2b) [de Vernal et al., 2013]. Furthermore, sea ice reached a minimum in northern Baffin Bay and the Canadian Arctic from 6 to 3 ka [Ledu et al., 2010; de Vernal et al., 2013], creating a source for moisture that was 2H-depleted compared to mod- ern winter precipitation around Lake N3. Although Baffin Bay still had seasonal sea ice during the middle Holocene, sea ice would have formed later in the year [Markus et al., 2009]. A loss of sea ice during early winter, when evaporation is greatest, can cause large increases in early winter snowfall [Bintanja and Selten, 2014]. Finally, the West Greenland Current was both strong and warm 6 to 4 ka, likely due to an increased contribution of the warm Irminger Current to the West Greenland Current, resulting in regional warmth and providing energy to evaporate more moisture (Figures 2c and 2d) [Perner et al., 2013]. Winter insolation was low during the middle Holocene [Laskar et al., 2004], so there was likely a large contrast between winter air temperature and winter ocean surface temperature. This temperature contrast would cause high evaporation. Thus, we inter- pret the significant middle Holocene depletion of Lake N3 I´2Haq as an increase in winter precipitation, caused by the near total loss of sea ice cover in the Labrador Sea, and the loss of early winter sea ice and increased ocea- nic heat advection in Baffin Bay.