Ancient plant DNA reveals High Arctic greening during the Last Interglacial

The Arctic is warming exceptionally rapidly, promoting an expansion of shrubs across the Arctic with global-scale climate implications. The Last Interglacial (∼125,000 y ago) was the most recent time the Arctic was warmer than present and thus serves as an analogue for Arctic greening in the near future. Ancient plant DNA in lake sediment from this time reveals major ecosystem changes in response to warmth, including an ∼400 km northward shift of dwarf birch relative to today. Enhanced shrub cover, corroborated by molecular and microfossil analyses, amplified warming during the Last Interglacial and will likely play a similar role in the future. This record constitutes the oldest authenticated plant DNA from lake sediment yet reported, increasing the technique's temporal potential.