摘要
地质历史中的暖期常被视为评价未来"人为变暖"的参考。新生代在总体降温的背景下发育了3个持续的温暖时期,早始新世、中中新世和上新世,地球依次经历了两极无冰、南极有冰和两极有冰的状态。多种指标重建结果显示,大气CO_2浓度在早始新世达到或超过2000ppmv,而在中中新世和上新世接近甚至低于现代水平(390ppmv),表明地球温度与大气温室气体浓度之间的不确定性明显。生物多样性在新生代暖期明显增加,亦与"人为变暖"导致生物多样性损失不符。据此认为,地质历史中的暖期不是未来"人为变暖"理想的相似形,但进一步认识这些暖期将有助于进一步理解气候系统内部因子相互作用、认识气候系统对温室气体浓度变化的敏感性以及改善气候模型的预测能力。
There have been numerous attempts to propose past warm periods as analogs for future anthropogenic warming. Against the background of progressive cooling,three permanent warm periods occurred within the Cenozoic,i. e. the Early Eocene,the Middle Miocene, and the Pliocene. During the Cenozoic,the Earth evolved from an ice-free,to an Antarctica glacial, and finally into today＇s planet with polar ice caps. Several proxies for both terrestriall and marine realms show that,atmospheric CO2 concentrations may reach to 2000ppmv during the early Eocene,and be close to, or even slightly lower than the present-day level（ ca. 390ppmv）during the Middle Miocene and the Pliocene. This discrepancy indicates great uncertainties between global warmth and increased atmospheric greenhouse gas concentration. Moreover, biotic evidence supports an increase in diversity during these warm intervals, inconsistent with the observed and predicted loss in biodiversity induced by recent anthropogenic warming. Thus, these past warm intervals fail as satisfactory geologic analogs for a future warming. However, they provide a valuable opportunity to understand the processes that operated during warm climate states, especially on the climate sensitivity of various CO2 concentrations,and to improve the prediction qualities of climate models.
出处
《第四纪研究》
CAS
CSCD
北大核心
2011年第6期1053-1059,共7页
Quaternary Sciences
基金
国家重点基础研究发展规划项目(973项目)(批准号:2010CB950204)
中国科学院知识创新工程重要方向项目(批准号:KZCX2-YWQ1-03)共同资助
关键词
新生代
暖期
人为变暖
温室气体
生物多样性
Cenozoic, warm periods, anthropogenic warming, greenhouse gas, biodiversity
