Assessing the Pace of a Rapid Climatic Event: The Late Paleocene Thermal Maximum

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Assessing the pace of a rapid climate transition: the Late Paleocene thermal maximumAbstract Seafloor sediments from about 55 million years ago document a climate transition involving extreme warming of oceanic and continental temperatures and changes in global weather patterns. This event is associated with a dramatic change in the global carbon cycle and is synchronous with significant species extinctions and diversification. It is also thought to have been extremely rapid, occurring over just a few thousand years. Although the cause of the climate transition is unknown, its apparent rapidity places tight constraints on allowable mechanisms. For example, a leading candidate is catastrophic release of methane hydrate from sediments to the atmosphere, promoting greenhouse warming. However, the rapidity of the climate change has been the subject of debate because the rate estimates are based on poorly constrained sedimentation models. The goal of this proposal is to better define the sedimentation history during this climate event by using the accumulation of cosmic dust particles as a proxy for sedimentation rate. Over short intervals the accretion rate of cosmic dust from space should be nearly constant, so the concentration of cosmic dust in sediments will be governed by dilution with sediment. By using 3He as a proxy of the cosmic dust concentration, the sedimentation history during this climate excursion will be determined from several Ocean drilling Program cores. This information will be used to better distinguish among possible causes of the climate transition.