GREENLAND CRETACEOUS PALEOCLIMATE FROM FLORAL STUDY

West Greenland floras are in a near continuous biostratigraphic sequence from the Early Cretaceous (Albian) to the Early Tertiary (Eocene) and will provide us a model of climatic change within a single region. Besides being a constraint on plant dispersal between continents in the Northern Hemisphere, the floras also are important for understanding the equator-to-pole temperature gradients necessary for determining air and ocean climate circulation models. Floras in the Arctic do not grown under climate conditions typical at lower latitudes. Low Arctic light levels play as much as a constraint on leaf physiognomy as cool temperatures and this added influence has not properly been assessed. The West Greenland Cretaceous floras indicate warmer terrestrial climates than considered by isotopic study of the Arctic oceans, computer modeling or even paleobotanical data from other sites in the Arctic. The basis of this is leaf physiognomy and not nearest living relative, leaf margin, or CLAMP analysis, which all have inherent difficulties rendering them as imprecise tools for climate study. Besides fossil taphonomic biases, low Arctic light levels, low mean annual range of Arctic temperatures, and lack of modern taxonomic analogues to Cretaceous plants all play roles in distorting the paleobotanical interpretation of Arctic temperatures.

In West Greenland, the Albian appears to be a period of cool temperate climates while towards the end of the Albian, climates were getting progressively warmer and drier. Mesic conditions existed during the Late Cretaceous (Turonian- Santonian) with mean annual temperatures probably 22-24⁰C. Ocean circulation from the opening Atlantic Ocean may have created climatic conditions warmer and wetter in Greenland than other Arctic areas.