Abstract Early Eocene (∼56–48 Ma) climates are useful to investigate polar climate dynamics in the absence of ice. We explore early Eocene orbital variability of Arctic climate using sediments recovered by the Arctic Coring Expedition (ACEX). High resolution records of lipid biomarkers (GDGTs; 2‐kyr) and palynological assemblages (5‐kyr) in the ∼4 m interval below Eocene Thermal Maximum 2 (∼54 Ma) show cyclic signals related to ∼20‐kyr precession, ∼40‐kyr obliquity, and ∼100‐kyr eccentricity. Biomarkers indicate obliquity and precession variability representative of sea surface temperature (SST) variations up to ∼1.4 and ∼0.5°C, respectively. Peak SSTs coincide with an elevated supply of pollen and spores and increased marine productivity. This implies an orbital control on precipitation and terrestrial nutrient supply to the Arctic Basin. Assuming that SST maxima correspond to Arctic insolation maxima (precession minima/obliquity maxima), precipitation maxima also correspond to insolation maxima, implying regional hydrological processes as a forcing rather than variations in meridional water transport, contrasting Pleistocene Arctic hydrology. The relative amplitudes of precession and obliquity in the SST record match that of local insolation between spring and fall, corroborating a seasonal GDGT bias. The reconstructed complete orbital imprint refutes a bias to one end of the orbital variability. Eccentricity‐related SST variability was ∼0.8°C, ∼2–3 times higher than synchronous variability in the deep ocean, and 3–4 times higher than similar variations in the tropics. This confirms eccentricity‐forced global temperature variability and that this had pronounced polar amplification, despite the absence of ice‐albedo feedbacks.

Chris D. Fokkema

Henk Brinkhuis

Francien Peterse

Appy Sluijs

Paleoceanography and Paleoclimatology

古海洋学和古气候学 (PALO) 发表有关过去环境、生物群和气候记录的论文。了解过去的地球系统需要采用广泛的方法，包括海洋和湖泊沉积学和洞穴岩浆；冰盖的形成和流动；稳定同位素、微量元素和有机地球化学；古生物学和分子古生物学；进化过程；生物体中的矿化；了解树木年轮的形成；地震地层学；物理、化学和生物海洋学；地球化学、气候和地球系统建模等。该期刊的范围是区域性到全球性的，而不是地方性的，并且包括任何地质时代的研究（前寒武纪到第四纪，包括现代类似物）。在这个框架内，将包括以下主题的论文：年代学、地层学（与古海洋学事件的相关性相关）、古构造、古海洋学建模、古循环（深、中、浅）、古气候学（例如，古风和冰冻圈历史)、全球沉积物和地球化学循环、缺氧、海平面变化和影响、生物进化与古海洋学之间的关系、生物危机、古生物学（例如，古海洋学中使用的“微化石”生态学）、古海洋学推断中的技术和方法，以及现代古海洋学类似物，以及耦合海洋-大气-生物圈过程的定量和综合分析。古海洋学和古气候研究使我们能够利用过去来获取有关未来可能的气候和生物发展的信息：过去是未来的关键，与现在相比，过去是过去的关键。

The journal "Paleoceanography and Paleoclimatology" publishes research papers on ancient environments, biomes, and climate records. Understanding past Earth systems requires a wide range of approaches, including marine and lake sedimentology, cave magma studies, the formation and flow of ice sheets, stable isotope analysis, trace elements and organic geochemistry, paleobiology and molecular paleobiology, evolutionary processes, mineralization phenomena, tree-ring formation, seismic stratigraphy, physical, chemical, and biological oceanography, geochemistry, climate, and Earth system modeling. The scope of the journal ranges from regional to global studies, covering research from any geological era (Precambrian to Quaternary, including modern analogs). Within this framework, the journal welcomes papers on the following topics: chronology, stratigraphy (related to paleoceanographic events), paleotectonics, paleoceanographic modeling, paleocirculation (deep, intermediate, shallow), paleoclimatology (e.g., ancient winds and cryosphere history), global sediment and geochemical cycles, anoxia, sea-level changes and impacts, the relationship between biological evolution and paleoceanography, biotic crises, paleobiology (e.g., the ecology of microfossils used in paleoceanography), techniques and methods in paleoceanographic inference, as well as modern paleoceanographic analogs, and quantitative and integrative analyses of coupled ocean-atmosphere-biosphere processes. Paleoceanography and paleoclimate studies enable us to leverage past information to gain insights into potential future climate and biological developments: the past is key to the future, and understanding the past is crucial for our present.

《Paleoceanography and Paleoclimatology》期刊发表关于古代环境、生物群落和气候记录的研究论文。理解过去的地球系统需要多种方法，包括海洋和湖泊沉积学、洞穴岩浆研究、冰盖的形成与流动、稳定同位素分析、微量元素和有机地球化学、古生物学与分子古生物学、进化过程、矿化现象、树木年轮的形成、地震地层学、物理、化学和生物海洋学、地球化学、气候与地球系统建模等。该期刊的研究范围从区域性到全球性，涵盖任何地质时代的研究（前寒武纪到第四纪，包括现代类比）。在这一框架下，期刊欢迎以下主题的论文：年代学、地层学（与古海洋学事件相关）、古构造、古海洋学建模、古循环（深、中、浅）、古气候学（如古风和冰冻圈历史）、全球沉积物与地球化学循环、缺氧、海平面变化及其影响、生物进化与古海洋学的关系、生物危机、古生物学（如古海洋学中使用的“微化石”生态学）、古海洋学推断中的技术与方法，以及现代古海洋学类比，此外，还包括海洋-大气-生物圈过程的定量与综合分析。古海洋学和古气候研究使我们能够利用过去的信息来预测未来可能的气候和生物发展：过去是未来的关键，过去的研究对现在的理解至关重要。

Category	Quartile
地球科学	2
地球科学, 古生物学	1
地球科学, 地球科学综合	2
地球科学, 海洋学	2

Orbital (Hydro)Climate Variability in the Ice‐Free Early Eocene Arctic

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