The North Atlantic Oscillation (NAO) determines wind speed and direction, seasonal heat, moisture transport, storm tracks, cloudiness and sea-ice cover through atmospheric mass balance shifts between the Arctic and the subtropical Atlantic. The NAO is characterized by the typical, yet insufficiently understood, seesaw pattern of warmer winter and spring temperatures over Scandinavia and cooler temperatures over Greenland during the positive phase of the NAO, and vice versa during the negative phase. We tested the potential to reconstruct NAO variation beyond the meteorological record through the application of a microphenological proxy. We measured the Undulation Index (UI) in Betula nana epidermal cells from herbarium leaf samples and fossil peat fragments dating back to 1865—exceeding most meteorological records in the Arctic—to estimate imprints of spring thermal properties and NAO in Greenland and Finland. We found negative relations between Greenland UI and late winter, spring and early summer NAO, and mostly positive, but not significant, relations between Finland UI and NAO in years with pronounced NAO expression. The direction of the UI response in this common circumpolar species is, therefore, likely in line with the NAO seesaw effect, with leaf development response to NAO fluctuations in northern Europe opposing the response in Greenland and vice versa. Increased knowledge of the UI response to climate may contribute to understanding ecological properties of key Arctic species, whilst additionally providing a proxy for NAO dynamics.

北大西洋涛动 (NAO) 通过北极和亚热带大西洋之间的大气质量平衡变化来确定风速和风向、季节性热量、水分输送、风暴轨迹、云量和海冰覆盖。NAO 的特点是典型但尚未充分了解的跷跷板模式，即在 NAO 的正相位期间，斯堪的纳维亚半岛的冬季和春季温度较高，格陵兰岛的温度较低，反之亦然。我们通过应用微物候代理测试了在气象记录之外重建 NAO 变化的潜力。我们测量了Betula nana的波动指数 (UI)  来自植物标本室叶子样本和化石泥炭碎片的表皮细胞可追溯到 1865 年——超过了北极的大多数气象记录——以估计格陵兰岛和芬兰春季热特性和 NAO 的印记。我们发现格陵兰 UI 与冬末、春季和初夏 NAO 之间存在负相关关系，在 NAO 表达明显的年份，芬兰 UI 与 NAO 之间的关系大多为正但不显着。因此，这种常见的极地物种的 UI 响应方向可能与 NAO 跷跷板效应一致，北欧对 NAO 波动的叶片发育响应与格陵兰岛的响应相反，反之亦然。增加对 UI 对气候响应的知识可能有助于了解关键北极物种的生态特性，