Carbonate Record of Past Thresholds, Critical Transitions and State Shifts in the Earth Systems

许多人担心，人类活动正在迅速将我们星球的生物圈和生态系统推向一种无法回头的替代状态。虽然没有人能预测下一次状态变化将在何时发生，地球将以多快的速度进入另一种状态，以及在变化之后等待我们的是什么样的世界，但地质记录为这些问题提供了一些答案，因为地球不止一次经历了全球范围的状态变化。最大的变化可以说是标志着我们地质历史的重大大灭绝，而没有什么比2.52亿年前的最近一次二叠纪大灭绝更具破坏性。许多作者认为，如果我们继续燃烧化石燃料，就会有可怕的事情发生。在这个场景中，超过92%的生物在短时间内从地球上消失了。西伯利亚圈闭喷发是有史以来最大的火山喷发，越来越多地被认为是造成全球破坏的主要原因，地球花了500万年才从破坏中恢复过来。然而，众所周知，地球系统在6000万年的时间间隔内跨越了一系列不可逆转的阈值，导致了这种转变，导致了关键的转变，这在碳酸盐沉积物中得到了特别好的记录。这些是发生在大约3.10、299、293、272、262和2.52亿年前的重大变化的短暂间隔。我们在这里建议通过对海洋碳酸盐系统的研究来研究这些关键的转变，该系统由于大气二氧化碳的增加而承受着越来越大的压力，就像现在一样。这将通过比较和对比相距甚远的地区的关键过渡来最好地解决。13名学生将参与在加拿大北极、美国西部、欧洲和中东举行的各种项目。这些地区曾经存在于超级大陆盘古大陆的西部和东部边缘，远在导致目前大陆格局的大陆漂移开始之前。所有项目都有一个现场部分，学生将在那里测量和采样详细的地层切片，以及一个实验室部分，他们将在那里获取额外的微观和化学数据。特别是考虑到当时海洋的组成和化学成分与现代海洋相似，研究遥远过去的海洋恶化与现代气候变化问题高度相关。我们的研究在考察遥远的地质历史的同时，可能会对未来世界将如何变化做出可信的预测，以应对人类活动。

Many fear that human activities are rapidly pushing our planet’s biosphere and ecosystems towards an alternate state from which it will be impossible to go back. While no one can predict when the next state shift will occur, how fast the planet will tip into an alternate state, and what kind of world awaits us beyond the shift, the geological record provides some answers to these questions as the Earth has more than once undergone state shifts of global magnitude. The largest shifts were arguably the major mass extinctions that marked our geological past, and none were more devastating than the Latest Permian Extinction, 252 million years ago. In a scenario that many authors see as the harbinger of horrific things to come if we keep burning fossil fuel, more than 92% of living creatures disappeared from planet Earth over a short period of time. The Siberian Traps eruptions, the largest volcanic eruptions to ever occur, are increasingly fingered as a major cause of the global devastation from which it took Earth 5 million years to recover. However, it is also known that the Earth Systems crossed a series of irreversible thresholds over a 60 million year interval leading-up to that shift resulting in critical transitions that are especially well recorded in carbonate sediments. These are short-lived intervals of major change that took place some 310, 299, 293, 272, 262 and 252 million years ago. We here propose to examine these critical transitions through the study of the marine carbonate system, which was, as it is now, under increasing stress due to an increase in atmospheric carbon dioxide. This will best addressed in comparing and contrasting the critical transitions across widely separated localities. Thirteen students will be involved in various projects that wil be staged in Arctic Canada, Western USA, Europe and the Middle East. These areas used to exist along the western and eastern margins of the supercontinent Pangea, well before the onset of continental drift that led to the present continent configuration. All projects have a field component where students will be measuring and sampling detailed stratigraphic sections and a laboratory component where they will be acquiring additional microscopic and chemical data. Looking into the oceanic deterioration in the distant past is highly relevant to the modern climate change issue, especially considering that the composition and chemistry of the oceans was at that time similar to that of the modern oceans. Our research, while looking into the distant geological past, could generate credible predictions about how the world will change in the future in response to human activities.