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 degrees C. The Paleocene-Eocene Thermal Maximum (PETM, similar to 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 degrees C) forests to the Arctic during the PETM and ETM2. Our data indicate that PETM mean annual temperatures were similar to 2 degrees to 3.5 degrees C warmer than those of the Late Paleocene. Mean winter temperatures in the PETM reached >= 5 degrees C (similar to 2 degrees 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.
1.US Geol Survey, Natl Ctr 926A, 12201 Sunrise Valley Dr, Reston, VA 20192 USA 2.Univ Utrecht, Dept Phys Geog, Princetonlaan 8a, NL-3584 CB Utrecht, Netherlands 3.Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9W,POB 1000, Palisades, NY 10964 USA 4.Brandon Univ, JR Brodie Sci Ctr, Dept Biol, 270 18th Sweet, Brandon, MB R7A 6A9, Canada 5.Univ Utrecht, Dept Earth Sci, Princetonlaan 8a, NL-3584 CB Utrecht, Netherlands 6.NIOZ Royal Netherlands Inst Sea Res, NL-1790 AB Den Burg, Texel, Netherlands
Recommended Citation:
Willard, Debra A.,Donders, Timme H.,Reichgelt, Tammo,et al. Arctic vegetation, temperature, and hydrology during Early Eocene transient global warming events[J]. GLOBAL AND PLANETARY CHANGE,2019-01-01,178:139-152