ABSTRACT During the Paleocene–Eocene, the Earth experienced the warmest conditions of the Cenozoic and reduced equator-to-pole temperature gradients. Compared to low- and mid-latitude sites, Paleogene environmental changes are less documented in Arctic regions, although such high latitude areas constitute a critical domain to constrain global climate changes. Floral and faunal assemblages indicative of exceptionally warm and humid conditions during the late Paleocene–early Eocene have been reported in several localities around the Arctic Ocean. Additional studies are required to ascertain the effects of Paleocene–Eocene global environmental changes on western Arctic regions. Here we present multiproxy data from early Eocene deltaic plain sediments of the Mackenzie Delta (Canada). This environment is characterized by littoral forest, including swamp, showing that the mangrove Avicennia grew in Arctic Canada near 75°N under air temperatures averaging 21–22 °C annually and 10–14 °C in winter and with precipitation of 1200–1400 mm/yr. Kaolinite contents are high (up to 75% of clay assemblages), as under a modern subtropical climate. The Avicennia pollens recently found in the New Siberian Islands and in Arctic Canada imply that warm and wet conditions were widespread along the Arctic coast during the early Eocene. It also suggests a marine connection between the Arctic Basin and the mid-latitude oceans. We propose that an oceanic current must have connected the Arctic Basin to the Atlantic and/or Pacific and that an internal current developed in the Arctic Basin since the early Eocene.

Abstract This synthesis incorporates the 16 most important pollen records available across the North Mediterranean region sensu lato for the last 2.7 Ma. Their location is discussed with respect to the present-day bioclimatic Mediterranean realm. A special effort has been made to redraw, where necessary, the pollen records in terms of modern cyclostratigraphy. The complexity of the evolution of the Mediterranean flora and vegetation as forced by the climatic cycles is evident. The influence of the latitudinal thermic (and xeric) gradient is confirmed, and the superimposition of a longitudinal gradient, forced by the Asian monsoon, is considered. The Mediterranean flora and vegetation were not altered by any important event during the Early-Middle Pleistocene transition between 1.2 and 0.7 Ma.