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Rainforest Response to Pennsylvanian Global Warming

雨林对宾夕法尼亚州全球变暖的反应

基本信息

批准号：
NE/F014120/2
负责人：
Howard James Falcon-Lang
金额：
$ 52.21万
依托单位：
Royal Holloway University of London
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FF014120%2F2
关键词：
Rainforest Response Pennsylvanian Global Warming

项目摘要

If global warming runs its course, what will be the effects on our planet? More specifically, how will the Earth's richest ecosystems - the tropical rainforests - cope with future changes? Some of the answers to these questions may lie in the ancient geological past. Three hundred million years, the Earth experienced global warming on a massive scale, completely melting the polar icecaps. About the same time, the tropical rainforests began to dieback. Did global warming trigger extinction? Not everyone agrees. Others point the finger at the jostling of the Earth's tectonic plates that forced up a Himalayan-scale mountain belt on the edge of the tropics. They claim that changes in elevation and geomorphology caused rainforest wipeout. From 2008-2013, I plan to lead a large team of international experts to investigate this important sequence of events in enormous detail. We want to know exactly how and why rainforest dieback occurred. Was it a slow protracted decline or an abrupt crunch, and was global warming or mountain building responsible? To achieve this end, we intend to work in the underground coalmines of Illinois, Kentucky and Indiana, USA. Here spectacular fossilized forests are preserved that date from the crucial time period. When we first reported these amazing discoveries back in April, they really captured the public imagination and triggered something of a 'media frenzy'. The extraordinary thing about these fossil forests is that they have been unearthed over thousands of hectares (the size of a city). This allows geologists like me to literally walk through the forests and see how species make-up changed across the ancient landscape. This shows us the forests were very complex, patchy ecosystems much like rainforest today. My team has now identified seven fossil forests stacked on top of each other. The fossil forests span a period of about two million years and crucially date from before and after the rainforest dieback. By studying these forests we can learn exactly how dieback occurred. What species were lost? How did ecosystems reorganize? How abrupt was the change? Of course, understanding rainforest dieback in this kind of detail doesn't tell us the cause. However, our North America rainforests were located more than a thousand kilometers from the nearest mountain belt, so we can rule out that option that a cause of change. So what about global warming? To find out what the climate was doing during the extinction event we plan to study pores in the leaves of the fossil trees called to stomata. Stomata allow plants to absorb carbon dioxide. Studies have shown that the more carbon dioxide there is the air, the less stomata plants produce. So, in effect, fossil leaves allow us to detect changes in the carbon dioxide levels. As carbon dioxide is an important greenhouse gas, changes in its concentration will affect climate. My colleagues will use other techniques using fossil soils to get independent estimates of past carbon dioxide levels. Together we will put together a high-resolution record of climate change through the key time interval. We will then see how the timing of climate change corresponds with the timing of rainforest dieback. Of course, even if it turns out that two events coincide, it doesn't necessarily mean that climate change caused rainforest dieback. You can never prove 'cause and effect' in the fossil record. However, colleagues will input our findings into computer climate simulations. This will test to see whether our observed climate change would lead to the observed rainforest dieback. This will help support any inferences we make about climate change and extinction. Although our three hundred million year old rainforests are not directly comparable to modern rainforests, our work will generally contribute to discussion on the nature and rate of rainforest dieback in the face of climate change, and help us better predict future changes.

如果全球变暖继续下去，将对我们的星球产生什么影响？更具体地说，地球上最丰富的生态系统--热带雨林--将如何应对未来的变化？这些问题的一些答案可能存在于古代地质历史中。3亿年后，地球经历了大规模的全球变暖，极地冰盖完全融化。大约在同一时间，热带雨林开始消亡。全球变暖是否引发了物种灭绝？不是每个人都同意这一点。其他人则将矛头指向地球构造板块的推挤，这些板块迫使热带边缘的喜马拉雅山脉地带向上移动。他们声称，海拔和地貌的变化导致了热带雨林的灭绝。从2008年到2013年，我计划领导一个由国际专家组成的庞大团队，对这一重要的事件序列进行极其详细的调查。我们想知道热带雨林死亡究竟是如何以及为什么发生的。这是一场缓慢而持久的衰退还是突然的危机，是全球变暖还是造山造成的？为了实现这一目标，我们打算在美国伊利诺伊州、肯塔基州和印第安纳州的地下煤矿工作。这里保存着壮观的化石森林，可以追溯到关键时期。今年4月，当我们第一次报道这些惊人的发现时，它们确实激发了公众的想象力，并引发了某种程度上的媒体狂热。这些化石森林的不同寻常之处在于，它们已经被发掘了数千公顷(相当于一个城市的大小)。这使得像我这样的地质学家可以在森林中穿行，看看古代景观中的物种构成是如何变化的。这向我们表明，当时的森林非常复杂，零星的生态系统很像今天的雨林。我的团队现在已经确定了七个堆积在一起的化石森林。化石森林的时间跨度约为200万年，关键是可以追溯到热带雨林死亡之前和之后。通过研究这些森林，我们可以确切地了解枯萎病是如何发生的。有哪些物种消失了？生态系统是如何重组的？这一变化有多突然？当然，了解热带雨林死亡的这种细节并不能告诉我们原因。然而，我们的北美热带雨林距离最近的山脉地带超过1000公里，所以我们可以排除这种选择是导致变化的原因。那么，全球变暖又如何呢？为了找出在物种灭绝事件期间气候的变化，我们计划研究被称为气孔的化石树叶子上的毛孔。气孔允许植物吸收二氧化碳。研究表明，空气中的二氧化碳越多，植物产生的气孔就越少。因此，实际上，化石树叶可以让我们探测到二氧化碳水平的变化。由于二氧化碳是一种重要的温室气体，其浓度的变化将影响气候。我的同事们将使用其他技术，利用化石土壤对过去的二氧化碳水平进行独立估计。我们将共同收集关键时间间隔内气候变化的高分辨率记录。然后，我们将看到气候变化的时机如何与雨林死亡的时机相对应。当然，即使事实证明这两个事件同时发生，也不一定意味着气候变化导致了热带雨林的死亡。你永远无法在化石记录中证明“因果关系”。然而，同事们将把我们的发现输入到计算机气候模拟中。这将测试我们观察到的气候变化是否会导致观察到的热带雨林死亡。这将有助于支持我们关于气候变化和物种灭绝的任何推论。尽管我们的三亿年前的热带雨林无法直接与现代热带雨林相提并论，但我们的工作总体上将有助于讨论面对气候变化的热带雨林死亡的性质和速度，并帮助我们更好地预测未来的变化。