Significantly warmer Arctic surface temperatures during the Pliocene indicated by multiple independent proxies

Abstract

Temperatures in the Arctic have increased by an astounding 1 °C in response to anthropogenic forcing over the past 20 years and are expected to rise further in the coming decades. The Pliocene (2.6-5.3 Ma) is of particular interest as an analog for future warming because global temperatures were significantly warmer than today for a sustained period of time, with continental configurations similar to present. Here, we estimate mean annual temperature (MAT) based upon three independent proxies from an early Pliocene peat deposit in the Canadian High Arctic. Our proxies, including oxygen isotopes and annual ring widths (MAT =-0.5 ± 1.9 °C), coexistence of paleovegetation (MAT =-0.4 ± 4.1 °C), and bacterial tetraether composition in paleosols (MAT =-0.6 ± 5.0 °C), yield es