廖宏,任小波,葛全胜,严中伟,林朝晖,周天军.气候变暖及其对二氧化碳浓度敏感性的新认识——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”之气候敏感性任务群研究进展[J].中国科学院院刊,2016,31(1):134-141.

气候变暖及其对二氧化碳浓度敏感性的新认识——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”之气候敏感性任务群研究进展

Climate Warming and Its Sensitivity to CO₂ Concentrations —Progress on “Climate Sensitivity” Group of CAS Strategic Priority Research Program “Climate Change: Carbon Budget and Relevant Issues”

廖宏
中国科学院大气物理研究所 北京 100029
Liao Hong
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
任小波
中国科学院重大科技任务局 北京 100864
Ren Xiaobo
Bureau of Major R&D Programs, Chinese Academy of Sciences, Beijing 100864, China
葛全胜
中国科学院地理科学与资源研究所 北京 100101
Ge Quansheng
Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
严中伟
中国科学院大气物理研究所 北京 100029
Yan Zhongwei
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
林朝晖
中国科学院大气物理研究所 北京 100029
Lin Zhaohui
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
周天军
中国科学院大气物理研究所 北京 100029
Zhou Tianjun
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China

         气候变化;温室气体浓度;气候敏感性;中科院战略性先导科技专项

        climate change;concentrations of greenhouse gases;climate sensitivity;CAS Strategic Priority Research Program

        大气中二氧化碳(CO₂)浓度不断增加导致的全球气候变暖引起了国际社会的广泛关注。2009 年哥本哈根大会已使 2 ℃ 阈值从科学认知演变为政治共识,即未来全球平均气温相对工业革命前的增温应该控制在 2 ℃ 之内,且相应的大气 CO₂ 当量浓度不超过 450 ppm。全球温度变化与温室气体浓度的对应关系,是减排目标的逻辑起点,本质上是 CO₂ 排放空间的问题。碳专项气候敏感性任务群从获取气候变化基础数据、发展完善中科院气候系统模式、预估全球 2 ℃ 增温对应的温室气体浓度及出现时间这3个方面进行了深入研究,取得了气候敏感性的一系列新认识。

        The increases in atmospheric concentrations of CO₂ and associated global warming are of worldwide concerns. In the 2009 Copenhagen Accord, many nations agreed to limit the increase in global temperature since pre-industrial times to below 2 ℃ by initiating significant cuts in global emissions of greenhouse gases, assuming that the global warming of 2 ℃ would occur if greenhouse gas concentrations rose above 450 ppm CO₂ equivalent by volume. Climate sensitivity (the ratio of change in global mean surface temperature to that in CO₂- equivalent concentration) is the scientific fundamental for policies to reduce emissions of greenhouse gases. To support the nation's mitigation and adaptation to climate change, a group of projects within the Chinese Academy of Sciences Strategic Priority Research Program of ‘Climate Change: Carbon Budget and Relevant Issues' examine the key factors that influence climate sensitivity, including natural variability of climate, the feedback of clouds and water vapor, the cooling effect of atmospheric aerosols, and the uncertainties associated with the global climate simulations. During the past four and a half years, the CAS scientists have improved the understanding of warming in China and climate sensitivity in the following aspects: (1) New time series of temperature are obtained and analyzed to understand the amplitude, rate, periodicity, and abrupt change of temperature in China. Time series of temperature for different regions over the past 2000 years are reconstructed based on datasets from tree rings, lake sediments, ice cores, coral, etc., and the time series of observed temperature from meteorological stations over the past 100 years are compiled. For climate series over the past 100 years, a homogenization approach is used to remove systematic biases in the observation series because of relocation of meteorological stations or changes in observation instruments, rules, and methods. The homogenized temperatures show that the average temperature over China increased by 1.52 ℃(100 yr)^{- 1}, which is much higher than the global warming of 0.89 ℃ over 1901—2012. (2) Observational networks are launched to measure size-resolved speciated aerosol concentrations and optical properties of aerosols. The continuous measurements nationwide provide valuable datasets for studies of climatic effect of aerosols. Comparisons of simulated aerosol concentrations from climate models with measurements show that current aerosol-climate models worldwide generally underestimate aerosol concentrations in China, suggesting that the climate models might have underestimated the roles of aerosols in climate sensitivity. (3) The key parameterization schemes of cloud-aerosol-radiation and dynamic vegetation have been implemented into the CAS Earth System Model, which allow us to better quantify the feedbacks of clouds and water vapor in climate system. (4) The multi-model transient simulations of future climate indicate that, under the Intergovernmental Panel on Climate Change(IPCC)future emissions scenarios (the Representative Concentration Pathways, RCPs), the warming of 2 ℃ would not occur under RCP2.6 and would likely occur when CO₂ equivalent concentrations are approximately 550 ppm under RCP4.5, RCP6.0, and RCP8.5.