Annually resolved North Atlantic marine climate over the last millennium.

Owing to the lack of absolutely dated oceanographic information before the modern instrumental period, there is currently significant debate as to the role played by North Atlantic Ocean dynamics in previous climate transitions (for example, Medieval Climate Anomaly-Little Ice Age, MCA-LIA). Here we present analyses of a millennial-length, annually resolved and absolutely dated marine δ18O archive. We interpret our record of oxygen isotope ratios from the shells of the long-lived marine bivalve Arctica islandica (δ18O-shell), from the North Icelandic shelf, in relation to seawater density variability and demonstrate that solar and volcanic forcing coupled with ocean circulation dynamics are key drivers of climate variability over the last millennium. During the pre-industrial period (AD 1000–1800) variability in the sub-polar North Atlantic leads changes in Northern Hemisphere surface air temperatures at multi-decadal timescales, indicating that North Atlantic Ocean dynamics played an active role in modulating the response of the atmosphere to solar and volcanic forcing. A lack of annually resolved climate records from the marine archive limits our understanding of oceanic processes. Here, the authors present a millennial-length, annually-resolved and absolutely-dated marine δ18O record from the shells of marine bivalves and offer insight into North Atlantic climate dynamics.

由于现代仪器测量时期之前缺乏有绝对年代的海洋学信息，目前对于北大西洋海洋动力学在以往气候转变（例如，中世纪气候异常 - 小冰期，MCA - LIA）中所起的作用存在重大争议。在此，我们对一个长达千年、具有年度分辨率且有绝对年代的海洋δ18O档案进行了分析。我们对来自冰岛北部大陆架的长寿海洋双壳贝类北极蛤（δ18O - 壳）贝壳的氧同位素比值记录进行了解释，将其与海水密度变化相关联，并证明太阳和火山强迫以及海洋环流动力学是过去千年气候变化的关键驱动因素。在工业化前时期（公元1000 - 1800年），北大西洋亚极地地区的变化在数十年时间尺度上领先于北半球地表气温的变化，这表明北大西洋海洋动力学在调节大气对太阳和火山强迫的响应方面发挥了积极作用。 海洋档案中缺乏具有年度分辨率的气候记录限制了我们对海洋过程的理解。在此，作者们展示了一个来自海洋双壳贝类贝壳的长达千年、具有年度分辨率且有绝对年代的海洋δ18O记录，并对北大西洋气候动力学提供了见解。