【摘要】 地球自5.4亿年前现代生态系统形成至今,发生了多次与碳循环扰动有关的重大气候事件.这些事件的触发机制、发展过程、环境变化及其伴随的生物响应型式为科学评估当今全球变化背景下生物多样性现状提供重要借鉴.然而,古-今生态系统变化时间尺度大不相同,高分辨率关键环境因子（温度、CO₂、降雨量、海洋氧化还原条件等）在深时记录中亦难以获取,深时海陆生物多样性模式尚缺乏高分辨率记录.因此,当今全球变化与深时记录对比存在巨大鸿沟.地球5.4亿年以来大部分时间处于两极无冰的温室状态,期间伴随多次极冷和极热气候事件,但地球深时重大生物演化和气候事件的关系复杂.生物多样性在变冷的奥陶纪早期、晚古生代大冰期、晚新生代大冰期以及中-晚三叠世和白垩纪热室期均呈现稳定增加,而在奥陶纪末冰期快速降温期间和二叠纪末、三叠纪末、白垩纪末火山排气作用导致的快速升温过程中急剧下降.地质时期生物多样性对气候变化的不同响应型式表明,生物多样性变化的根本驱动因素可能不是简单的温度、大气CO₂浓度等环境因子的背景值高或低,而是环境因子的变化速率（环境变率）.变率较小,环境相对稳定,生物有足够的时间适应环境变化,生物多样性不会丧失,甚至繁盛.反之,若环境因子变率过大,超出了生态系统的承受力,生物来不及适应,生物多样性就会显著降低,甚至引发大灭绝.已有模拟和计算表明,当今地球碳排放的速度有可能超过了地质历史时期任何一次生物大灭绝事件.因此,避免环境突变事件和生物大灭绝的再次发生成为政界、科学界和普通民众关注的焦点.打通地球多圈层界限,开展古-今地质记录、冷-热极端气候、海-陆生态系统和长-短时间尺度的综合对比研究,并通过建立适用于深时的地球系统模型,模拟重大生物和环境事件的背景与发生过程,是地球系统科学未来发展的重要方向.更多还原

【Abstract】 Climate changes are altering Earth’s biodiversity in very complex ways while predicting the evolutionary trajectories of Earth’s ecosystem response to the current global changes is highly challenging. The Earth has witnessed multiple climate extremes associated with profound perturbations in the global carbon cycle since the formation of modern ecosystems 540million years ago. Unraveling the triggering and terminating mechanisms, the environmental perturbations, and the associated biological responses to these climate extremes can provide a basis to anticipate and manage the responses of biodiversity to the current changing climates. However, these efforts have been hampered by major challenges concerning the vast differences in the time scales of deep-time and modern ecosystem changes, the lack of high-resolution and reliable environmental proxy data（temperature, CO₂, precipitation, ocean redox conditions, etc.）, and the missing of highresolution marine and terrestrial biodiversity curves. Therefore, those challenges bring a huge gap in comparison between current global changes and the deep-time archives. Although the Earth has been in greenhouse conditions for most of the past 540 million years（i.e., where the poles were ice-free）, there were numerous climate extremes such as glaciations and hyperthermal events. Unfortunately, the relationships between major biological revolutions（extinctions and radiations） and climatic events in deep time are more complex than expected. For instance, biodiversity exhibited a steady increase during the Early Ordovician cooling, the Late Paleozoic Ice Age, the Late Cenozoic Ice Age, and the greenhouse intervals from the Middle-Late Triassic and Cretaceous. In contrast, biodiversity underwent rapid decline during the rapid cooling of the Late Ordovician glaciation and during the rapid warming periods associated with volcanic CO₂degassing at the end of the Permian, the end of the Triassic, and the end of the Cretaceous. The different response patterns of biodiversity to climate changes in deep-time led us to realize that the fundamental driving factors of biodiversity change may not simply be the background values of environmental factors such as temperature and CO₂, but what really matters is the rate of environmental change. Specifically, when the rate of environmental change is small, namely, the environment is relatively stable, organisms have enough time to adapt to environmental changes and biodiversity will not be lost or even undergo flourish; on the contrary, if the rate of environmental change is too sharp, exceeding the tipping point for the ecosystems,organisms do not have enough time to adapt and biodiversity will be significantly reduced and even lead to mass extinctions. The limited deep-time carbon emission data from numerical models suggest that the present-day CO₂emission rate exceeded any intervals during major extinction events in geological history. Therefore, avoiding environmental catastrophes and mass extinctions against future impacts has become a top priority. Here, we propose integrated multidisciplinary research through breaking multi-layer boundaries of the Earth, and carrying out comparative studies of deep-time and modern geological records, glacial and hyperthermal climates, marine and terrestrial ecosystems, and longterm and short-term time scales. Simulating interactions between biological and environmental events by establishing deep-time Earth system models is also a clear avenue to go. Those integrative studies will bring essential constraints for the prediction of the impact of climatic perturbations on future biodiversity trajectories, which is critical given the current concerns about the consequences of the ongoing 6th mass extinction. These are also important directions for Earth system science studies in the future.更多还原