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不可逆转的状态。虽然没有人能预测下一次状态转变会在什么时候发生，地球进入另一种状态的速度有多快，以及在这种转变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，因为地球已经不止一次经历了全球性的状态转变。最大的变化可以说是标志着我们地质历史的主要物种灭绝，而最具破坏性的莫过于2.52亿年前的最新二叠纪物种灭绝。许多作者认为，如果我们继续燃烧化石燃料，那么92%以上的生物在短时间内从地球上消失，这预示着可怕的事情即将到来。西伯利亚地盾火山爆发是有史以来规模最大的火山爆发，越来越多的人认为它是造成全球大灾难的主要原因，地球花了500万年才从这场灾难中恢复过来。然而，我们也知道，地球系统在6000万年的间隔中跨越了一系列不可逆转的阈值，导致了这种转变，导致了碳酸盐沉积物中特别详细记录的关键转变。这些短暂的变化发生在大约3.1亿、299亿、293亿、272亿、262亿和2.52亿年前。我们在此建议通过海洋碳酸盐系统的研究来检验这些关键的转变，由于大气中二氧化碳的增加，海洋碳酸盐系统现在受到越来越大的压力。这个问题最好通过比较和对比各地区的关键转变来解决。13名学生将参与各种项目，这些项目将在加拿大北极、美国西部、欧洲和中东上演。这些地区曾经存在于超大陆盘古大陆的西部和东部边缘，早在大陆漂移开始之前就形成了现在的大陆结构。所有的项目都有一个实地部分，学生将测量和采样详细的地层剖面，以及一个实验室部分，他们将获得额外的微观和化学数据。研究遥远过去的海洋退化与现代气候变化问题高度相关，特别是考虑到当时海洋的成分和化学成分与现代海洋的成分和化学成分相似。我们的研究，在考察遥远的地质历史的同时，可以对未来世界将如何因人类活动而变化做出可信的预测。

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.