Regional Contrasts in LGM to Holocene Warming Trends in the Terrestrial Arctic: Insights from Sedimentary Ancient DNA

A synthesis of proxy studies from the terrestrial Arctic reveals conflicting patterns regarding the extent and timing of the Holocene summer temperature maximum. This is unexpected, as summer insolation—acting at the hemispheric scale—is generally assumed to be the primary driver. Regional differences have largely been attributed to proxy-related uncertainties.

In this study, we introduce a new quantitative proxy for terrestrial climate change by leveraging sedimentary ancient DNA (plant metabarcoding) from lake sediments. Our dataset spans 22 sites across Siberia, Alaska, and western Canada, covering the last 26,000 years. The reconstruction error is notably low (<1°C) compared to other proxies.

Our findings indicate that the temperature maximum across all records occurred around 10,000 years ago, with temperatures averaging 1.5°C above the late Holocene mean and approximately 4°C warmer than the Last Glacial Maximum (LGM) average. While the large-scale trend generally aligns with summer insolation patterns, we observed strong regional variations, particularly in areas affected by shelf flooding. These regions were relatively warm during the glacial period compared to the Holocene, as the sites were situated more distant from the coasts.

Importantly, our sedimentary ancient DNA-based reconstructions are validated by transient simulations using an Earth System Model (ESM) with adjusting land-sea mask which show similar pattern.