Research Articles

The effects of global warming are documented and predicted to be most pronounced in the Arctic, a region which plays a crucial, but not yet well understood role within the global climate system (1). Reliable climate projections for high northern latitudes are, however, hampered by the complexity of the underlying natural variability and feedback mecha-nisms (2, 3). To date, information concerning the natural climate varia-bility in the Arctic is widely restricted to the last glacial-interglacial cycle, the period covered by the longest ice-core records from the Green-land ice cap (4). A limited number of records extend deeper in time, both from the marine realm (5) and from the Arctic borderland (6), but these records are restricted in terms of age control and temporal resolution. Here we present a time-continuous and high-resolution record of en-vironmental history from the Arctic spanning the past 2.8 Ma, from Lake El’gygytgyn, located ~100 km to the north of the Arctic Circle in north-eastern Russia (67.5°N, 172°E, Fig. 1). The length, temporal continuity, and centennial to millennial-scale temporal resolution (Fig. 2 and sup-plementary materials) provide a de-tailed view of natural climatic and environmental variability in the terres-trial Arctic, a better understanding of the representative nature of the last climate cycle for the Quaternary, and how sensitive the terrestrial Arctic reacts to a range of forcing mecha-nisms. Lake setting, drilling, and core analyses. Lake El’gygytgyn is located in a meteorite impact crater formed 3.58 Ma ago (7). The 170 m deep lake has a bowl-shaped morphology with a diameter of ca. 12 km, a surface area of 110 km2, and a relatively small catch-ment of 293 km2 (8). The modern con-tinental Arctic climate produces herb-dominated tundra in the catchment, nine months per year of lake-ice cover, and oligotrophic to ultra-oligotrophic conditions in the lake. Low productivi-ty in combination with complete over-turning of the water column during the ice-free period in summer leads to well-oxygenated bottom waters throughout the year. Scientific deep drilling was per-formed in the El’gygytgyn Crater in winter 2008/09 (9). The core compo