深海沉积与全球变化研究的前缘与挑战  

Deep-sea sediments and global change:Research frontiers and challenges

作　　者：刘志飞[1] 陈建芳 石学法 LIU Zhifei;CHEN Jianfang;SHI Xuefa(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;Key Laboratory of Marine Ecosystem Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China;Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]自然资源部第二海洋研究所海洋生态系统动力学重点实验室,浙江杭州310012 [3]自然资源部第一海洋研究所海洋地质与成矿作用重点实验室,山东青岛266061

出　　处：《地学前缘》2022年第4期1-9,共9页Earth Science Frontiers

基　　金：国家自然科学基金项目(42130407);上海市“科技创新行动计划”国际科技合作项目(20590780200)。

摘　　要：海洋正在经历变暖和酸化等人类活动引发的全球变化的影响,而深海沉积储存着地球演变历史时期由自然因素驱动过去全球变化的详细档案,通过探究其现今和过去全球变化过程,能够揭示全球变化的特征和规律,为预测未来变化提供依据。近年来在该领域的突出研究进展,是针对社会选择的未来排放轨迹,在深海记录中都能够找到相应的类似情形,用于评估未来地球系统各种变化的过程和后果。其中,以Dansgaard-Oeschger变化为代表的千年尺度事件、以厄尔尼诺南方涛动(ENSO)和北大西洋涛动(NAO)为代表的十年尺度气候变化事件,是最接近现今地球变暖的快速气候变化场景。地球系统的发展轨迹目前正处于人类排放温室气体的“热室地球”路径的起点上,如果地球超过了这个“临界点”,它将沿着一条不可逆的道路进入“热室地球”状态,另一种路径则是通向“稳定地球”状态。深海沉积档案中的类似情形能够为社会选择未来排放的轨迹提供重要参考。全球变化研究面临的重大挑战是重新认识其关键过程的理论机制。以海洋变暖和酸化影响硅藻和颗石藻的海洋生物泵过程为例,传统知识认为酸化有利于硅藻建造,但最新的围隔实验研究却发现酸化大幅减少全球硅藻输出;传统知识认为酸化导致海洋生物钙化危机,但近期针对中生代大洋缺氧事件的黑色页岩研究,发现颗石藻的碳酸钙输出在海洋酸化期间大幅增加。这些颠覆性的认识严重挑战了传统全球变化某些关键过程的理论体系。Present-day oceans are experiencing the effects of global change such as warming and acidification caused by human activities.Deep-sea sediments store a detailed archive of past global changes driven by nature during Earth's evolution.By exploring today's and past global change processes,we can reveal the characteristics and laws of global change and provide a basis for predicting future changes.The outstanding research progresses made in recent years were the discovery in the deep-sea of a variety of analogous scenarios that humans,when choosing future greenhouse gas emission trajectories,can reference to for evaluating future changes—their processes and consequences—in the Earth system.Among such scenarios,millennium-scale climate events,represented by the Dansgaard-Oeschger oscillation,and decadal-scale climate events,represented by the El Nino-Southern Oscillation(ENSO)and the North Atlantic Oscillation(NAO),are the closest rapid climate change analogues to today's global warming.The Earth system is currently at the beginning of a“Hothouse Earth”emission trajectory.If the system passes the“tipping points”,it will follow an irreversible path to a“Hothouse Earth”state;whereas an alternative path may lead to a“Stabilized Earth”state.Analogous scenarios in the deep-sea sedimentary archive can provide societies with valuable information in choosing future emission trajectories.The major challenges for researchers are to fully understand the mechanisms of the key processes of global change.Taking the example of ocean warming and acidification's influence on diatom and coccolithophore functioning as marine biological pump.The conventional knowledge has suggested that acidification is beneficial to diatom formation;but recent mesocosm experiments have found that global diatom output is significantly reduced.Likewise,the suggestion that acidification leads to calcification crisis in marine life has also been proven wrong,as recent black shale studies of Mesozoic oceanic anoxic events showed that ca

关 键 词：深海沉积 全球变化 海洋变暖 海洋酸化 快速气候变化 临界点 

分 类 号：P736.2[天文地球—海洋地质] P531[天文地球—海洋科学] P467[环境科学与工程—环境科学] X16