Tripati Aradhna, Elderfield Henry
Department of Earth Sciences, University of Cambridge, Downing Street, CB2 3EQ, UK.
Science. 2005 Jun 24;308(5730):1894-8. doi: 10.1126/science.1109202.
A rapid increase in greenhouse gas levels is thought to have fueled global warming at the Paleocene-Eocene Thermal Maximum (PETM). Foraminiferal magnesium/calcium ratios indicate that bottom waters warmed by 4 degrees to 5 degrees C, similar to tropical and subtropical surface ocean waters, implying no amplification of warming in high-latitude regions of deep-water formation under ice-free conditions. Intermediate waters warmed before the carbon isotope excursion, in association with downwelling in the North Pacific and reduced Southern Ocean convection, supporting changing circulation as the trigger for methane hydrate release. A switch to deep convection in the North Pacific at the PETM onset could have amplified and sustained warming.
温室气体水平的迅速上升被认为是古新世-始新世极热事件（PETM）期间全球变暖的推动因素。有孔虫的镁/钙比率表明，底层海水温度上升了4摄氏度至5摄氏度，类似于热带和亚热带表层海水温度，这意味着在无冰条件下，深水形成的高纬度地区的变暖没有加剧。中间层海水在碳同位素偏移之前就已经变暖，这与北太平洋的下沉流和南大洋对流减弱有关，这支持了环流变化是甲烷水合物释放的触发因素。在PETM开始时，北太平洋转向深层对流可能会加剧并维持变暖。
