Summer warmth between 15,500 and 15,000 years ago enabled human repopulation of the northwest European margin.

High-magnitude decadal to centennial-scale abrupt changes in climate had a transformative effect on many past human populations. However, our understanding of these human/climate relationships is limited because robust tests of these linkages require region-specific quantified palaeoclimatic data with sufficient chronological precision to permit comparisons to the archaeological record. Here we present new high-resolution palaeoclimatic data and combine these with radiocarbon inventories of archaeological and faunal material, to test the relationship between abrupt warming and the ability of humans to rapidly repopulate the northwest margins of Europe (>50° N and encompassing the area of Britain, Ireland, the surrounding islands and the North Sea basin) after regional abandonment during the Last Glacial Maximum. We address the timing of this process and the relevance of the abrupt climate changes recorded in the Greenland ice cores. We use the IntCal20 radiocarbon calibration curve to show that the earliest human repopulation in this region occurred up to 500 years before the climate of Greenland warmed. However, our analyses show that parts of the northwest European margin had already experienced substantial summer warming by this time, probably driven by changes of sea-ice area in the eastern North Atlantic. The associated warming influenced the distribution of key hunter-gatherer prey species such as reindeer, which were a key resource for humans. Accordingly, this study highlights asynchrony in seasonal warming across the North Atlantic region during the last deglaciation and shows that this asynchrony permitted human exploitation of northwest European margin paraglacial landscapes by ~15,200 years before the present.