Gradual warming prior to the end-Permian mass extinction

The biggest known mass extinction in the history of animal life occurred at the Permian-Triassic boundary and has often been linked to global warming. Previous studies suggested that a geologically rapid (less than 40 kyr) temperature increase of more than 10°C occurred simultaneously with the main extinction pulse. This hypothesis is challenged by geochemical and palaeontological data indicating profound environmental perturbations and a temperature rise prior to the main extinction. Using Secondary Ion Mass Spectrometry (SIMS), we measured oxygen isotope ratios from Changhsingian (Late Permian) ostracods of northwestern Iran. Our data show that ambient seawater temperature began to rise at least 300 kyr prior to the main extinction event. Gradual warming by approximately 12°C was probably responsible for initial environmental degradation that eventually culminated in the global end-Permian mass extinction.动物生命史上已知规模最大的集群灭绝事件发生于二叠纪-三叠纪之交，且常与全球变暖相关联。既往研究提出，地质尺度上的快速升温（不足4万年）幅度超过10℃，且与主要灭绝脉冲同步发生。该假说受到地球化学与古生物学数据的挑战——这些数据表明，在主要灭绝事件发生前，环境已发生深刻扰动且温度出现上升。本研究利用二次离子质谱（Secondary Ion Mass Spectrometry, SIMS），对伊朗西北部长兴阶（晚二叠世）的介形类化石开展氧同位素比值测定。我们的数据显示，环境海水温度至少在主要灭绝事件发生前30万年便已开始上升。约12℃的逐步升温或许引发了初始环境退化，并最终演变为全球性的二叠纪末集群灭绝事件。