The Paleocene‐Eocene Thermal Maximum (PETM; 56 Ma) is considered to be one of the best analogs for future climate change. The carbon isotope composition (δ¹³C) of n‐alkanes derived from leaf waxes of terrestrial plants and marine algae can provide important insights into the carbon cycle perturbation during the PETM. Here, we present new organic geochemical data and compound‐specific δ¹³C data from sediments recovered from an early Cenozoic basin‐margin succession from Spitsbergen. These samples represent one of the most expanded PETM sites and provide new insights into the high Arctic response to the PETM. Our results reveal a synchronous ∼−6.5‰ carbon isotope excursion (CIE) in short‐chain n‐alkanes (nC₁₉; marine algae/bacteria) with a ∼−5‰ CIE in long‐chain n‐alkanes (nC₂₉ and nC₃₁; plant waxes) during the peak of the PETM. Although δ¹³C_n‐alkanes values were potentially affected via a modest thermal effect (1‰–2‰), the relative changes in the δ¹³C_n‐alkanes remain robust. A simple carbon cycle modeling suggests peak carbon emission rate could be ∼3 times faster than previously suggested using δ¹³C_TOC records. The CIE magnitude of both δ¹³C _n‐C19 and δ¹³C_n‐C29 can be explained by the elevated influence of ¹³C‐depleted respired CO₂ in the water column and increased water availability on land, elevated pCO₂ in the atmosphere, and changes in vegetation type during the PETM. The synchronous decline in δ¹³C of both leaf waxes and marine algae/bacteria argues against a significant contribution to the sedimentary organic carbon pool from the weathering delivery of fossil n‐alkanes in the Arctic region.

中文翻译：

---

PETM期间高北极地区的同步海洋和陆地碳循环扰动

古新世-始新世最大温度（PETM; 56 Ma）被认为是未来气候变化的最佳模拟之一。碳同位素组合物（δ ¹³ C）的ñ -烷烃从陆生植物和海洋藻类的叶蜡衍生的能提供了重要的见解的PETM期间碳循环扰动。在这里，我们提出了新的有机地球化学数据和化合物特异性δ ^13个C数据从沉积物从次卑尔根早期新生代盆缘连续回收。这些样品代表了PETM扩展最广泛的地点之一，并为北极对PETM的高响应提供了新的见解。我们的结果表明，短链正构烷烃（n C₁₉ ; 在PETM峰值期间，长链正构烷烃（n C ₂₉和n C ₃₁；植物蜡）中CIE约为-5‰的海洋藻类/细菌。虽然δ ^13个C ^ _{ñ -烷烃}值通过适度的热效应（1‰-2‰）可能受影响，在δ的相对变化¹³ Ç _{ñ -烷烃}保持稳健。一个简单的碳循环模型表明峰值碳排放率可能会更快〜3倍，比以前使用δ建议^13个Ç _TOC记录。两者δ的CIE大小¹³ Ç _{Ñ -C19}和δ¹³ C _{n -C29}可以通过在水柱中增加¹³ C消耗的呼吸CO _2的影响和增加土地上的水分利用，大气中p CO _2的升高以及PETM期间植被类型的变化来解释。在δ同步下降¹³既叶蜡和海洋藻类/细菌的Ç反驳了从化石风化输送沉积有机碳池显著贡献ñ -烷烃在北极地区。