Measurements of Last Interglacial stable water isotopes in ice cores show that central Greenland d18Oincreased by at least 3& compared to present day. Attempting to quantify the Greenland interglacialtemperature change from these ice core measurements rests on our ability to interpret the stable waterisotope content of Greenland snow. Current orbitally driven interglacial simulations do not show d18O ortemperature rises of the correct magnitude, leading to difficulty in using only these experiments toinform our understanding of higher interglacial d18O. Here, analysis of greenhouse gas warmed simulationsfrom two isotope-enabled general circulation models, in conjunction with a set of Last Interglacialsea surface observations, indicates a possible explanation for the interglacial d18O rise. A reduction in thewinter time sea ice concentration around the northern half of Greenland, together with an increase in seasurface temperatures over the same region, is found to be sufficient to drive a >3& interglacialenrichment in central Greenland snow. Warm climate d18O and dD in precipitation falling on Greenlandare shown to be strongly influenced by local sea surface condition changes: local sea surface warmingand a shrunken sea ice extent increase the proportion of water vapour from local (isotopically enriched)sources, compared to that from distal (isotopically depleted) sources. Precipitation intermittencychanges, under warmer conditions, leads to geographical variability in the d18O against temperaturegradients across Greenland. Little sea surface warming around the northern areas of Greenland leads tolow d18O against temperature gradients (0.1e0.3& per �C), whilst large sea surface warmings in theseregions leads to higher gradients (0.3e0.7& per �C). These gradients imply a wide possible range ofpresent day to interglacial temperature increases (4 to >10 �C). Thus, we find that uncertainty about localinterglacial sea surface conditions, rather than precipitation intermittency changes, may lead to thelargest uncertainties in interpreting temperature from Greenland ice cores. We find that interglacial seasurface change observational records are currently insufficient to enable discrimination between thesedifferent d18O against temperature gradients. In conclusion, further information on interglacial sea surfacetemperatures and sea ice changes around northern Greenland should indicate whether þ5 �C duringthe Last Interglacial is sufficient to drive the observed ice core d18O increase, or whether a larger temperatureincreases or ice sheet changes are also required to explain the ice core observations.