Closing the temporal gap: ecological responses to past extinction events

不断上升的二氧化碳水平和人类活动正在把地球的生态系统推向一种以前只在气候变暖导致的物种大灭绝期间经历过的状态。这些古代变暖事件的化石记录为我们提供了直接证据，说明在气候变化和生物多样性丧失时期，地球生态系统是如何构建和运作的，它们是如何应对这些变化的，最重要的是，它们是如何恢复的。化石记录中的信息应该有助于我们更好地了解地球当今的生态系统将如何应对持续变暖，并帮助我们检验对未来变化的预测。以这种方式使用化石记录的一个问题是，大多数研究都是在数万年或数十万年的长时间尺度上观察过去发生的变化，但今天的生态学家和生物学家更感兴趣的是几年、几十年和几百年后会发生什么。这个项目试图缩小这个时间差距，这样我们就可以对过去和现在进行更有意义的比较。我们能不能看看几百万年前发生的变化在我们今天感兴趣的相似的时间尺度上？我们认为我们可以。多年来，测年技术得到了改进，我们对灭绝事件的年龄有了更精确的测量。此外，气候变化往往会导致更多的风化作用，导致更多的泥土和淤泥被从陆地冲到大陆架海域。这些物质堆积在厚厚的沉积物中，保存了更多关于过去的细节。最后，气候变化还导致了海底“死亡区”的扩大，这些地区没有氧气，无法养活任何穴居动物。没有穴居动物意味着海底得到了更好的保护。我们已经确定了两次灭绝事件——晚二叠纪和早陶瓦纪——它们是由全球变暖引起的，时间很长，在低氧条件下沉积在海底的厚岩石序列。我们的目标是从这些化石记录中收集样本，并在这些样本中计数和识别微小的浮游生物、陆地植物的孢子和花粉，以了解陆地和海洋上的群落是如何随着时间而变化的。我们希望能够看到在几千年或几百年的尺度上发生的反应，我们将以生态学家分析现代生态系统的同样方式分析这些变化。我们的研究将产生数百个样本，要看完所有样本需要很多年的时间，所以我们也将尝试利用人工智能（机器学习）来加快这一过程。如果我们成功了，那么我们将对过去的两次灭绝事件进行最详细的研究，并将能够利用化石证据和现代生态系统的数据来帮助我们了解未来生态对当今变暖的反应。

Rising carbon dioxide levels and human activities are pushing Earth's ecosystems to a state that they have previously only experienced during warming-induced mass extinctions of the past. The fossil records of these ancient warming events provide us with direct evidence of how our planet's ecosystems were structured and functioned at times of climate change and biodiversity loss, how they responded to such changes and, most importantly, how they recovered. Information locked in the fossil record should help us better understand how Earth's present-day ecosystems will respond to continued warming, and help us test predictions of future change. One problem with using the fossil record in that way is that most studies look at past changes that occurred on long timescales of tens of thousands or hundreds of thousands of years, but ecologists and biologists today are more interested in what will happen in years, decades and centuries. This project seeks to try and close this temporal gap so that we can make more meaningful comparisons between the past and present. Can we look at changes that happened millions of years ago on similar timescales that we are interested in today? We think we can. Dating techniques have improved over the years and we have much more precise measurements for the ages of extinction events. Also, climate change tends to cause more weathering, which leads to more mud and silt being washed off the land and into the shelf seas. This accumulates in great thicknesses of sediment which preserve alot more detail about the past. Finally, climate change also leads to expanding 'dead zones' on the seafloor - areas without oxygen that cannot support any burrowing animals. The lack of burrowing animals means a better preserved seafloor. We have identified two extinction events - the Late Permian and the Early Toarcian - that were caused by global warming and which are well-dated, with thick rock successions that were deposited on the seafloor under low oxygen conditions. We aim to collect samples from those fossil records and to count and identify the microscopic plankton and spores and pollen of land plants in those samples, to understand how communities on land and in the sea were changing through time. We hope to be able to see responses that took place on the scale of millenia or centuries, and we will analyse those changes in the same way that ecologists analyse modern ecosystems. Our study will generate hundreds of samples and it would take many years to look through all of them, so we are also going to try to harness artificial intelligence (machine learning) to speed up the process for us. If we're successful then we will have the most detailed study ever made of these two past extinction events, and will be able to use the fossil evidence alongside data from modern ecosystems to help inform our understanding of future ecological responses to present-day warming.