大气CO2浓度的持续增加将对气候和生态环境造成何种程度的影响，是人类亟需回答的重大科学问题。解决该问题的一个有效途径是研究过去温暖期的生态环境响应。早始新世(56-50 Ma)有两个显著特征：一是百万年尺度持续的增温过程；二是在长期增温过程中，地表系统发生了一系列历时短暂的(~10万年)、幅度递减的快速增温事件。无论从构造尺度还是事件尺度，早始新世均呈现出以CO2主导的温室气候，为评估未来气候变化的后果提供了理想的相似型。为此，本项目拟选取南阳盆地和江汉盆地湖相沉积物为研究载体，通过对早始新统地层δ13C时间序列的高分辨率重建，识别出早始新世的热事件；在此基础上，通过年代学、沉积学、孢粉学和地球化学的研究，系统重建华中地区早始新世暖期时气候、环境要素及生态系统的演变历史，着重探讨陆地环境和植被对CO2浓度增高事件的响应方式和响应速率。本项目的实施将为评估未来增温后果提供地质依据。

To evaluate the impacts of ever-increasing atmospheric CO2 concentration on future climate and biota, it is desirable to study the environmental and ecological effects of the ancient greenhouse climate forced by CO2. The Early Eocene period (56-50 Ma) was characterized by the millions of long-term warming trend and a series of geologically abrupt (~100 kyr) global warming events with the magnitude weakening. Whether on long timescales or shorter timescales, the Early Eocene period was marked by the CO2-forcing greenhouse climate, and thus provides an ideal analogue for future climate change. Therefore, we plan to systematically reconstruct the high-resolution time series of δ13C based on the Early Eocene lacustrine sediments from the Nanyang Basin and Jianghan Basin, in order to identify the Early Eocene hyperthermals; and then, we will reconstruct the change in climate, environment and ecosystem during the Early Eocene warm period in central China, based on the study of chronology, sedimentology, geochemistry and palynology; further, we will discuss how the elevated CO2 events affected terrestrial environment and vegetation. The implementation of this project will provide the geological scenario for assessing the impacts of future global warming.