Early Eocene Climatic Optimum

Wildfire activity in early Paleogene greenhouse conditions can be used as an analogue to gauge the effect of future warming trends on wildfire in the current climate system. Inertinite (fossil charcoal in coal) from 11 autochthonous early Paleogene lignite seams from the Schöningen mine (Germany) was quantified using macerations, in situ pillars and industry standard crushed samples. A new three transect method was developed to quantify in situ charcoal. The combination of in situ pillars and crushed samples accounts for temporal and spatial variation in charcoal through a stratigraphically oriented pillar, whilst maintaining comparability with industry standards and previous work. Charcoal occurs as a range of randomly distributed particle sizes, indicating that fires were burning locally in the Schöningen peat-forming environment and in the surrounding areas, but according to petrological data, not in an episodic or periodic pattern. Although charcoal abundance is low (relative to previous high fire worlds such as the Cretaceous), three quantitative and semi-quantitative methods show increased wildfire activity (relative to the modern world) in the warmest parts of the early Paleogene. As atmospheric oxygen levels stabilised to modern values and precipitation and humidity became the main control on wildfire, increased rainfall followed by drier intervals would have created an environment rich in dry fuel in which wildfires could easily propagate if humidity was low enough. In the later part of the Early Eocene (Ypresian) charcoal abundance fell to levels similar to those found in modern peats. This indicates that the transition to the modern low fire world occurred within the Early Eocene, earlier than previous records suggest.

This study describes 21 species of Caenogastropoda collected in the Macunköy section from the upper part of the Kırkkavak Formation (Haymana-Polatlı Ba- sin, SW of Ankara). The known stratigraphical range of the studied species is consistent with an earlyYpresian (early Eocene) age of the deposits, indicated by Cerithium puigcercosensis (Cossmann, 1897) n. comb. and Tympanotonos turris (Deshayes, 1833). This result supports previous biostratigraphic studies based on benthic foraminifers. Among the caenogastropods from the Macunköy section, two new species are described: Bellatara ankaraensis n. sp. and Vicinoceri thium seni n. sp. Furthermore, Cerithium puigcercosensis n. comb. is described as a new combination. The gastropod assemblage of the M acunköy section indicates a mangrove-fringed, wet coastal ecosystem with euryhaline conditions, connected to coastal swamps and a delta system.

Estimates of pCO2 for the early Paleogene vary widely, from near modern-day levels to an order of magnitude greater, based on various proxy measures. Resolving the relationship between climate and pCO2 during this globally warm period is a key task in understanding climate dynamics in a warmer world. Here, we use the stomatal frequency of fossil Ginkgo adiantoides from the Okanagan Highlands of British Columbia, Canada to estimate pCO2 during the Early Eocene Climatic Optimum (EECO), the interval of peak warmth in the Cenozoic. We also examine a dataset of modern Ginkgo biloba leaves to critically assess the accuracy and precision of stomatal frequency as a proxy indicator of pCO2. Early Eocene fossil G. adiantoides has significantly lower stomatal frequency than modern G. biloba, suggesting pCO2 levels N2× modern preindustrial values. This result is in contrast to earlier studies using stomatal frequency of Ginkgo that indicated near modern-day levels of pCO2 in the early Paleogene, though not including samples from the EECO. We also find that levels of pCO2 as indicated by stomatal frequency are correlated with trends in climate (mean annual temperature) over time at the Falkland fossil locality, suggesting that climate and pCO2 were coupled during the EECO hyperthermal.