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Communities have been shaped in numerous ways by past climatic change; this process continues today. At the end of the Pleistocene epoch about 11,700 years ago, North American communities were substantially altered by the interplay of two events. The climate shifted from the cold, arid Last Glacial Maximum to the warm, mesic Holocene interglacial, causing many mammal species to shift their geographic distributions substantially. Populations were further stressed as humans arrived on the continent. The resulting megafaunal extinction event, in which 70 of the roughly 220 largest mammals in North America (32%) became extinct, has received much attention. However, responses of small mammals to events at the end of the Pleistocene have been much less studied, despite the sensitivity of these animals to current and future environmental change. Here we examine community changes in small mammals in northern California during the last ‘natural’ global warming event at the Pleistocene–Holocene transition and show that even though no small mammals in the local community became extinct, species losses and gains, combined with changes in abundance, caused declines in both the evenness and richness of communities. Modern mammalian communities are thus depauperate not only as a result of megafaunal extinctions at the end of the Pleistocene but also because of diversity loss among small mammals. Our results suggest that across future landscapes there will be some unanticipated effects of global change on diversity: restructuring of small mammal communities, significant loss of richness, and perhaps the rising dominance of native ‘weedy’ species. [ABSTRACT FROM AUTHOR]

Analyzes backscatter images and sub-bottom profiler records obtained during the 1999 expedition of the SCICEX submarine in the Arctic Ocean. Discovery of multiple bedforms indicative of glacial scouring and moulding of the sea floor, combined with large-scale erosion of submarine ridge crests; How these distinct glaciogenic features demonstrate that immense, Antarctic-type ice shelves of up to 1 kilometer thick and hundreds of kilometers long existed in the Arctic Ocean during Pleistocene glaciations.

Presents research which created two simple models that successfully simulate each glacial-interglacial cycle over the late Pleistocene epoch with the correct time and amplitude. Earth's climate over the past million years; Factors in glacial-interglacial cycles; Astronomical theory of climate.