过去2万年以来气候变化的影响与人类适应——中国科学院战略性先导科技专项“应对气候变化的碳收支认证及相关问题”之影响与适应任务群研究进展

Effect of Paleoclimate Changes and Human Adaptation——Progress on “Impact and Adaptation” Group of CAS Strategic Priority Research Program “Climate Change: Carbon Budget and Relevant Issues”

在当前全球气候变化背景下,中科院战略性先导科技专项"应对气候变化的碳收支认证及相关问题"之"影响与适应任务群"主要以全新世大暖期为"相似型",研究全球平均增温约1°C—2°C情形下的我国环境格局及其对陆地生态系统的可能影响,为人类适应提供自然背景及参照;探讨过去不同气候环境背景下人类的适应方式,揭示人类适应气候变化的规律和模式,为未来人类如何适应气候变化提供启示。通过近5年的工作,在自然背景研究方面,揭示出目前的全球增温有自然变暖的周期背景,且不同尺度的增温总体有利于我国季风区降水增加,导致森林面积扩大,我国北方沙漠区收缩,陆地生态系统碳储量增加。在人类起源与适应研究方面,获得了东亚地区现代人起源和迁徙的新证据,揭示出过去的气候变暖促进了农作物的栽培与驯化。8 ka BP—6 ka BP,稻作和旱作农业在空间上显著扩展,农业技术的进步促使史前人类在青藏高原大规模定居。一般情况下,过去寒冷的气候条件限制了人口发展,而相对暖湿的气候有利于人口的增加和文化的发展。研究同时显示,近70年来我国海岸带陆地面积由于人类活动加剧而增加近14 200 km^2。未来工作应加强高分辨率气候变化历史的定量重建,加强气候-环境-人类活动相互作用的机制等研究。

The response of environmental change and human adaptation to global climate changes, as well as their role in climate, has been a subject of much debate. The motivation for the Impact and Adaptation task group of CAS Strategic Priority Research Program Climate Change： Carbon Budget and Relevant Issues , originated in understanding the climate of the Holocene Megathermal period--an epoch that many consider as the closest analogue to future greenhouse conditions with global temperature increasing by 1-2℃. The core issues of the project are to evaluate the effect of the past warming climate on the environmental pattern and terrestrial ecosystems in China, which provided the natural background for human adaptation. This is combined with exploring the how humans adapted to different climatic and environmental conditions, offering a potential future analogue for climate changes impact humans. During the last five years, our project revealed the current global warming has a natural warming cycle background and that global warming at different scales favors an increase in monsoonal rainfall, resulting in the expansion of forested areas, contraction of the deserts in north China, and increasing carbon storage in terrestrial ecosystems. In the study of human genesis and adaptation, our project has obtained new evidence for the origin and migration of Homo Sapiens in East Asia and demonstrated that the cultivation and domestication of crops was facilitated by past climate warming. During the Holocene Megathermal period, the spatial distribution of rice and millet agriculture expanded remarkably, and the advances of agricultural technology facilitated permanent human occupation of the Tibetan Plateau. In general, past climate cooling limited population size, and mild climates spurred the growth in prehistoric populations and advances in human cultures. We also found that the land area of coastal zones in China have increased nearly 14 200 km^2 in the last 70 years, which resulted from the intensified human activities. In future work, we will focus on the quantitative reconstruction of high-resolution paleoclimate changes, and investigate the mechanisms of interactions between climate, environment, and human activities.