Accurate And Precise Alkenone Records Of Atmospheric CO2 For The Pliocene And Beyond To Inform The Future

准确、精确的上新世及以后大气二氧化碳的烯酮记录，为未来提供信息

基本信息

批准号：
NE/X000567/1
负责人：
Marcus Badger
金额：
$ 82.55万
依托单位：
The Open University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2023
资助国家：
英国
起止时间：
2023 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FX000567%2F1
关键词：
Accurate Precise Alkenone Records Atmospheric

项目摘要

Human activity is changing the composition of the Earth's atmosphere at a rate not seen for millions of years. The burning of fossil fuels for energy production releases carbon dioxide, which, once in the atmosphere increases the trapping of heat near to the planet's surface. While the physical basis of this process (known as the greenhouse effect) is well established by the scientific community the sensitivity, in terms of rate and magnitude of responses, of the Earth's surface environment to changes in CO2 is associated with some uncertainty. Given the climate crisis that we face, one of the most important things that we can learn from the past is how the Earth's climate system operates under a range of different atmospheric compositions in order to understand, to mitigate, and to act to prevent negative impacts of human activity. The geological record of Earth history allows us to insight into the climate system by studying the vast array of natural experiments which it records, and by viewing the action of the actual (and whole) system, we can develop and test the climate models which are the best way to predict our climate future. To this end, this project aims to reduce uncertainty in our understanding of the Earth System, both by improving one of the main ways by which we measure ancient atmospheric CO2 concentrations, and by producing a record of CO2 in unprecedented detail over a critical interval in Earth history, the Pliocene.The Pliocene (an interval of time 5.33 to 2.58 million years ago) has long interested climate scientists. It was warmer than present, and previous work (including some by us) has shown that it is the most recent time when CO2 was as high or higher than it is today. In the context of all of Earth history it is relatively recent meaning that many of the factors that influence climate change on very long timescales, like the position of the continents and the composition and distribution of ecosystems, are very similar to today. This means that the Pliocene is an ideal time interval to test exactly how the climate system works, and how it responds to changing CO2 in a warm world. This sets it aside from the more recent, great Pleistocene ice ages when the world was generally cooler.As the Pliocene was before the great ice ages, we cannot rely on ice core records to determine atmospheric greenhouse gases. We must instead estimate past carbon dioxide concentrations by measuring chemical signatures found in molecules (called alkenones) preserved in deep-sea sediments, which were made by plankton which lived in the oceans millions of years ago. Whilst this method has been applied for over twenty years, recent concerns have been raised over the accuracy and precision of the technique (including in work by the PI). In this project we will develop improved ways of measuring the chemical signatures of the alkenones, and, building on further recent work by the PI, cross-check and calibrate the alkenone technique against Pleistocene ice core CO2 records. This will build a new framework for confidently applying the alkenone system for interrogating the Pliocene (by us) and throughout the full 66 million years of the Cenozoic (in future projects) opening up even more natural experiments for study.The substantial global community effort to document in great detail the temperature changes within the Pliocene (in projects such as PRISM, PlioVAR and PlioMIP) mean that fantastic records of global surface temperature already exist. These are crying out for atmospheric carbon dioxide records of similar quality, which we will provide. Together, these temperature and carbon dioxide records will provide a critical new understanding of how our climate system works in a warm, future-relevant world.

人类活动正在以数百万年来从未见过的速度改变地球大气的成分。燃烧化石燃料来生产能源会释放二氧化碳，二氧化碳一旦进入大气层，就会增加地球表面附近热量的滞留。虽然这一过程（称为温室效应）的物理基础已被科学界充分确立，但地球表面环境对二氧化碳变化的响应速度和幅度的敏感性与一些不确定性相关。鉴于我们面临的气候危机，我们可以从过去学到的最重要的事情之一是地球气候系统如何在一系列不同的大气成分下运行，以便了解、减轻和采取行动防止负面影响人类活动。地球历史的地质记录使我们能够通过研究它记录的大量自然实验来深入了解气候系统，并通过观察实际（和整个）系统的行为，我们可以开发和测试气候模型预测气候未来的最佳方法。为此，该项目旨在减少我们对地球系统理解的不确定性，方法是改进我们测量古代大气二氧化碳浓度的主要方法之一，并在关键时间间隔内以前所未有的详细程度记录二氧化碳。地球历史，上新世。上新世（5.33 至 258 万年前的一段时间）长期以来一直引起气候科学家的兴趣。当时比现在温暖，之前的工作（包括我们的一些工作）表明，这是二氧化碳浓度与今天一样高或更高的最近一次。在整个地球历史的背景下，它是相对较新的，这意味着在很长的时间尺度上影响气候变化的许多因素，例如大陆的位置以及生态系统的组成和分布，与今天非常相似。这意味着上新世是准确测试气候系统如何运作以及它如何响应温暖世界中二氧化碳变化的理想时间间隔。这将它与最近的更新世大冰河时代区分开来，当时世界普遍较凉爽。由于上新世是在大冰河时代之前，我们不能依靠冰芯记录来确定大气中的温室气体。相反，我们必须通过测量深海沉积物中保存的分子（称为烯酮）中发现的化学特征来估计过去的二氧化碳浓度，这些沉积物是由数百万年前生活在海洋中的浮游生物产生的。虽然这种方法已经应用了二十多年，但最近人们对该技术的准确性和精确性（包括 PI 的工作）提出了担忧。在这个项目中，我们将开发测量烯酮化学特征的改进方法，并在 PI 最近的进一步工作的基础上，根据更新世冰芯 CO2 记录交叉检查和校准烯酮技术。这将建立一个新的框架，以便自信地应用烯酮系统来探究上新世（由我们）和整个新生代的 6600 万年（在未来的项目中），为研究开辟更多的自然实验。详细记录了上新世的温度变化（在 PRISM、PlioVAR 和 PlioMIP 等项目中）意味着全球表面温度的奇妙记录已经存在。这些都迫切需要类似质量的大气二氧化碳记录，而我们将提供这些记录。总之，这些温度和二氧化碳记录将为我们的气候系统如何在温暖的、与未来相关的世界中发挥作用提供重要的新认识。