Ancient forests and climates of the Paleogene of Canada

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The Paleogene - from 65 to 24 million years ago (Ma) - was a geological interval of substantial climate change and consequent evolution of both plant communities and the various species that they were composed of. Paleogene climate change was driven by a number of factors, including natural changes in atmospheric carbon dioxide (CO2) levels. In western North America, over the Paleogene plant communities shifted from predominantly subtropical forest types to a mix of temperate forests more typical of eastern North America today, and open grasslands. This change was driven largely by a shift from globally warm and wet climates, especially during the Late Paleocene (61-55 Ma) and Early Eocene epochs (55-49 Ma), to cooler and drier climates by the Oligocene epoch (34 Ma) and the formation of ice caps on Antarctica and Greenland by the Oligocene. The research aims to use well preserved fossil sites in western Canada, principally from British Columbia, to reconstruct climates and forest ecosystems from the acme of warm climates during the Paleogene, the Early Eocene Climatic Optimum (EECO). During the Paleocene and Early Eocene epochs numerous lines of evidence have reconstructed atmospheric CO2 levels 2x to 5x present day levels, but uncertainty remains over the role CO2 played in warming EECO climates. The BC fossil sites preserve a diverse suite of the leaves of many of the trees and other plants that are today typical of the deciduous forests of eastern North America, and especially so the warmer southeast (e.g. palms), together with plant types such as the Chinese rubber tree (Eucommia sp.) and the dawn redwood (Metasequoia sp.), that are found today in southeast Asia. Also present are suites of insects exhibiting a diversity otherwise expected in a tropical setting. The BC Eocene fossil sites provide a natural laboratory to look at how ecosystems have responded to climate change in the past, as well as exploring questions about the evolution of the deciduous forests and the origins of tropical forest diversity.