The second of the two big articles I alluded to is out at GSA Special Publications. We brought together 11 experts in their fields to take another look at this keystone site in the Canadian High Arctic. Amongst its unique features is a marine/estuarine muddy layer with molluscs from both the Pacific and Atlantic-derived Arctic, demonstrating the Bering Strait was open at or by this time. But we didn't stop at the molluscs. Magnetostratigraphy, Amino Acid racemerisation, oribatid mites, ostracods, beetles, macroflora, moss, pollen, dendrology, stratigraphy and so much more. It was a privilege to bring it together with this team. Thank you to the staff at GSA who found insightful reviewers during the height of the pandemic. ABSTRACT Meighen Island, in the Canadian Arctic Archipelago, is one of the most important localities for study of the late Neogene Beaufort Formation because of the presence of marine sediments interbedded with terrestrial fossiliferous sands. The stratigraphic succession, fossils from the marine beds, correlation with reconstructions of sea level, and paleomagnetic data from the Bjaere Bay region of the island suggest that the Beaufort Formation on Meighen Island was likely deposited either at 3.2–2.9 Ma or during two intervals at ca. 4.5 Ma and 3.4 Ma. The exposed Beaufort Formation on Meighen Island probably encompasses at least one warm interval and eustatic sea- level highstand of the Pliocene. Fossils of plants and arthropods are abundant in the alluvial sands exposed in the Bjaere Bay region. The lower part of the sequence (Unit A), beneath the mud- dy marine sequence (Unit B), contains plant taxa that have not been seen above the marine beds. Sediments below the marine beds are dominated more by fossils of trees, whereas the organic debris from above marine beds contains many fossils of plants, insects, and mites characteristic of open treeless sites. Regional tree line probably occurred on Meighen Island during deposition of the upper sediments, which implies a mean July climate at least 9 °C warmer than at present. When the marine sedi- ments were deposited, nearshore water temperatures probably did not fall below 0 °C; hence, the Arctic Ocean probably lacked perennial ice cover. This confirms recent modeling experiments exploring the causes of Arctic amplification of temperature that have found the removal of sea ice to be a key factor in resolving previous proxy- model mismatches. Barendregt, R.W., Matthews, J.V., Jr., Behan-Pelletier, V., Brigham-Grette, J., Fyles, J.G., Ovenden, L.E., McNeil, D.H, Brouwers, E., Marincovich, L., Rybczynski, N., and Fletcher, T.L., 2021, Biostratigraphy, Age, and Paleoenvironment of the Pliocene Beaufort Formation on Meighen Island, Canadian Arctic Archipelago: Geological Society of America Special Paper 551, p. 1–39, https://doi.org/10.1130/2021.2551(01).
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ProjectClouds cause the greatest uncertainty in climate models, but we currently have no way of testing cloud model performance in a climate with higher CO2 than the historical records. Palaeontology gives us access to such a past, but currently, we don't have a method to reconstruct cloud in deep time. Archives
June 2023
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