(Table 1) Radiocarbon ages of organic remains in Oyogos Yar ice-wedge samples and corresponding d18O values

Arctic climate has experienced major changes over the past millennia that are not fully understood in terms of their controls and seasonality. Stable-data from ice wedges in permafrost provide unique information on past winter climate. Recently, an ice-wedge record from the Lena River Delta suggested for the first time that Siberian winter temperatures increased throughout the Holocene, contradicting most other Arctic paleoclimate reconstructions which are likely biased towards the summer. However, the representativeness of this single record and the spatial extent of its reconstructed winter warming signal is unclear. Here, we present a new winter temperature record based on paired stable oxygen (d18O) and radiocarbon age data spanning the last two millennia from the Oyogos Yar coast in northeast Siberia. The record confirms the long-term winter warming signal as well as the unprecedented temperature rise in recent decades. This confirmation demonstrates that winter warming over the last millennia is a coherent feature in the northeastern Siberian Arctic, supporting the hypothesis of an insolation-driven seasonal Holocene temperature evolution followed by a strong warming likely related to anthropogenic forcing.

过去数千年来，北极气候发生了诸多重大变化，但其驱动机制与季节变化特征仍未得到充分阐明。永久冻土（permafrost）中的冰楔（ice wedge）稳定同位素数据可为古冬季气候研究提供独特视角。近期，一项来自勒拿河三角洲的冰楔记录首次揭示：全新世（Holocene）以来西伯利亚冬季气温呈持续上升趋势，这与多数其他北极古气候重建（paleoclimate reconstructions）结果相悖——后者大概率因偏向夏季气候信号而存在系统性偏差。然而，该单一记录的代表性及其重建的冬季增温信号的空间覆盖范围仍不明确。本研究基于西伯利亚东北部奥约戈斯亚尔海岸过去2000年的成对稳定氧同位素（d18O）与放射性碳年代（radiocarbon age）数据，构建了一条全新的冬季气温序列。该序列证实了长期冬季增温信号，以及近几十年来前所未有的气温上升现象。这一证实表明，近千年来的冬季增温是西伯利亚东北部北极地区的一致性特征，支持了如下假说：全新世气温的季节演化由太阳辐射（insolation）驱动，后续则出现了大概率与人为强迫（anthropogenic forcing）相关的显著增温。