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

评估快速气候转变的速度：晚古新世热极大期摘要大约5500万年前的海底沉积物记录了一次气候转变，涉及海洋和大陆温度的极端变暖以及全球天气模式的变化。这一事件与全球碳循环的急剧变化有关，并与重大的物种灭绝和多样化同步。它也被认为是非常迅速的，发生在短短几千年内。虽然气候转变的原因尚不清楚，但其明显的快速性对允许的机制施加了严格的限制。例如，一个主要的候选者是甲烷水合物从沉积物中灾难性地释放到大气中，促进温室效应。然而，气候变化的速度一直是争论的主题，因为速率估计是基于约束不佳的沉积模型。该提案的目标是通过使用宇宙尘埃颗粒的积累作为沉积速率的替代，更好地确定这一气候事件期间的沉积历史。在很短的时间间隔内，来自太空的宇宙尘埃的吸积速率应该是几乎恒定的，因此沉积物中宇宙尘埃的浓度将取决于沉积物的稀释作用。通过使用3He作为宇宙尘埃浓度的替代物，将从几个大洋钻探计划的岩心中确定这次气候漂移期间的沉积历史。这些信息将用于更好地区分气候转变的可能原因。

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.