Sub-centennially resolved reconstruction of surface temperature on High Arctic Svalbard for the past 13,000 years

• First instrumental lake alkenone temperature calibration using Mass Spectrometry Imaging. • Early Holocene temperatures were warmer than today, but colder than previously shown. • Early Holocene peak warmth equals temperatures shown for probable 2100 CE scenarios. • Peak warming was driven by the compounding effects of insolation and ocean circulation. • Svalbard terrestrial paleotemperature history extended into the Younger Dryas stadial. The Arctic warms much faster than Earth’s average temperature. This amplified regional response has numerous global impacts. Notably, sea-ice loss changes planetary energy budgets, melting land ice contributes to sea-level rise, and thawing permafrost increases carbon emissions. Despite these consequences, predictions remain uncertain because future change exceeds the range of the scarce instrumental observations used to calibrate climate models. Quantitative paleoclimate data can close this gap by providing long-term empirical constraints. Information from past warm periods is particularly relevant to inform future change scenarios, especially when changes are resolved on human-relevant timescales. Here, we present a sub-centennial-scale temperature reconstruction for the past 13 ka with a focus on the warmer-than-present Early Holocene (11.7 to 8.2 ka BP). To do so, we analyzed lake sediments from the Svalbard archipelago – a High Arctic climate hotspot with a heightened sensitivity to changes in key components of the regional climate system like sea ice and ocean circulation. To quantify past growing temperature variability, we relied on the U 37 K alkenone unsaturation index. To allow direct comparison of our record with observations as well as predictions, we calibrated μm-scale core top U 37 K values determined by Mass Spectrometry Imaging (MSI) against local spring air temperature measurements. The resulting reconstruction indicates that Early Holocene temperatures peaked around 9 ka BP and were up to 3.5 °C warmer than today, which is similar to probable warming scenarios for 2100 CE. Our results also show that Younger Dryas stadial temperatures were milder than during the earliest Holocene.