Spatial and temporal variability of Holocene temperature in the North Atlantic region

The early Holocene climate of the North Atlantic region was influenced by two boundary conditions that were fundamentally different from the present: the presence of the decaying Laurentide Ice Sheet (LIS) and higher than present summer solar insolation. In order to assess spatial and temporal patterns of Holocene climate evolution across this region, we collated quantitative paleotemperature records at sub-millennial resolution and synthesized their temporal variability using principal components analysis (PCA). The analysis reveals considerable spatial variability, most notably in the time-transgressive expression of the Holocene thermal maximum (HTM). Most of the region, but especially areas peripheral to the Labrador Sea and hence closest to the locus of LIS disintegration, experienced maximum Holocene temperatures that lagged peak summer insolation by 1000–3000 years. Many sites from the northeastern North Atlantic sector, including the Nordic Seas and Scandinavia, either warmed in phase with maximum summer insolation (11,000–9000 years ago) or were less strongly lagged than the Baffin Bay–Labrador Sea region. These spatially complex patterns of Holocene climate development, which are defined by the PCA, resulted from the interplay between final decay of the LIS and solar insolation forcing.