Search

[1] Evidence is mounting that abrupt climatic shifts occurred during the last glacial-interglacial transition (LGIT) in the North Atlantic and other regions. However, few high-resolution climatic records of the LGIT exist from the high latitudes of the North Pacific rim. We analyzed lake sediments from southwestern Alaska for biogenic silica, organic carbon, organic nitrogen, diatom assemblages, and compound-specific hydrogen isotopes. Results reveal climatic changes coincident with the Younger Dryas, Intra-Allerod Cold Period, and Pre-Boreal Oscillation. However, major discrepancies exist in the paleoclimate patterns of the Bolling-Allerod interstadial between our data and the GISP2 δ18O record from Greenland, and causes are uncertain. These data suggest that the North Pacific and North Atlantic experienced similar reversals during climatic warming of the LGIT but that the Bolling-Allerod cooling trend in the GISP2 δ18O record is probably not a hemispheric or global pattern.

[1] The Himalayan region of northern India depends on monsoon rains, together with snow and glacial melt, to supply life-sustaining water to one of the world's most densely populated areas. Here we provide high-resolution pollen and diatom evidence from a peat deposit in the Pinder Valley that shows a synchronous and abrupt ecosystem turnover toward a wetter state in the last two centuries that exceeded changes recorded over the last three millennia. Contrary to expectations, there was no relationship between recent proxy changes and summer monsoon precipitation. Strong relationships, however, were found with winter climate data. We link this recent unprecedented wetness to marked warming at higher elevations resulting in increased seasonal runoff and associated climatic feedbacks in this snow and ice-melt dominated region. In contrast to the expected desiccation and decomposition of most peat systems with warming, this site has instead become the wettest in its ca. 3500-year history.