Arctic vegetation, temperature, and hydrology during Early Eocene transient global warming events

Global and Planetary Change
By: , and 

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Abstract

Early Eocene global climate was warmer than much of the Cenozoic and was punctuated by a series of transient warming events or ‘hyperthermals’ associated with carbon isotope excursions when temperature increased by 4–8° C. The Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma) and Eocene Thermal Maximum 2 (ETM2, 53.5 Ma) hyperthermals were of short duration (< 200 kyr) and dramatically restructured terrestrial vegetation and mammalian faunas at mid-latitudes. Data on the character and magnitude of change in terrestrial vegetation and climate during and after the PETM and ETM2 at high northern latitudes, however, are limited to a small number of stratigraphically restricted records. The Arctic Coring Expedition (ACEX) marine sediment core from the Lomonosov Ridge in the Arctic Basin provides a stratigraphically expanded early Eocene record of Arctic terrestrial vegetation and climates. Using pollen/spore assemblages, palynofacies data, bioclimatic analyses (Nearest Living Relative, or NLR), and lipid biomarker paleothermometry, we present evidence for expansion of mesothermal (Mean Annual Temperatures 13–20˚C) forests to the Arctic during the PETM and ETM2. Our data indicate that PETM mean annual temperatures were ~1.8˚ - 3.5˚C warmer than the Late Paleocene. Mean winter temperatures in the PETM reached ≥6°C (~1.9˚C warmer than the late Paleocene), based on pollen-based bioclimatic reconstructions and the presence of palm and Bombacoideae pollen. Increased runoff of water and nutrients to the ocean during both hyperthermals resulted in greater salinity stratification and hypoxia/anoxia, based on marked increases in concentration of massive Amorphous Organic Matter (AOM) and dominance of low-salinity dinocysts. During the PETM recovery, taxodioid Cupressaceae-dominated swamp forests were important elements of the landscape, representing intermediate climate conditions between the early Eocene hyperthermals and background conditions of the late Paleocene.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Arctic vegetation, temperature, and hydrology during Early Eocene transient global warming events
Series title Global and Planetary Change
DOI 10.1016/j.gloplacha.2019.04.012
Volume 178
Year Published 2019
Language English
Publisher Elsevier
Contributing office(s) Climate Research and Development
Description 14 p.
First page 139
Last page 152