中美俄加陆域碳汇对人为增温的消减贡献

作为主要的气候强迫因子,CO₂与人类活动密切相关,但很多研究往往忽视了陆地生态系统碳汇对人为排放CO₂增温的消减作用。俄罗斯、加拿大、中国和美国是世界上地域面积最大、且社会经济处于不同发展阶段的4个国家,将短时期内CO₂排放所引起的辐射强迫进行量化分析,对于评估人为和自然因素对气候的影响非常重要。本文基于CO₂同化数据,利用“碳—气候”参数化方案,在分析人为碳排放及其气候效应的同时,考虑陆地生态系统碳汇的气候效应,进而得到4个国家的全球辐射强迫。结果显示：① 2000—2016年,4个国家人为排放的CO₂均呈明显增加趋势（0.125 Pg C a ^-1）,但陆地生态系统的碳汇作用也不断增强（0.003 Pg C a ^-1）;其中,中美两国总的人为碳排放占了4个国家的87.19%,而俄罗斯陆地生态系统的吸收碳能力最强,总量达14.69 Pg C。② 截至2016年,陆地生态系统的降温效应达-0.013 W m ^-2,可消减人为碳排放增温效应的45.06%。充分说明若不考虑陆地生态系统,将会明显高估人为碳排放的增温效应。③ 整体上,相对于2000年和工业革命前的CO₂浓度水平,4个国家总的人为碳排放分别贡献了0.32 W m ^-2和0.42 W m ^-2的全球辐射强迫。本文还进一步探讨了温度与辐射强迫的线性关系,相对于单一的人为或者自然因素而言,综合两者的辐射强迫,与相应时段的气温变化可解释度最高,达30.3%。

Contribution of terrestrial carbon sink to future warming in China,the United States,Russia and Canada

As a major climate forcing factor,CO2 is closely related to human activities,but many studies have overlooked the carbon absorption of terrestrial ecosystem to anthropogenic carbon emissions.China,the United States,Russia and Canada are the four countries with the largest area in the world at different socio-economic development stages.Quantifying the global radiative forcing contribution of CO2 emissions is important for assessing the climate effects of human and natural factors.Based on CO2 assimilation data,this study used a "carbonclimate " parameterization scheme to analyze the anthropogenic carbon emissions and its climatic effects while considering the climate effects of carbon sinks of terrestrial ecosystem.Then we obtained the net global radiative forcing contributions of the four countries.The results showed that the anthropogenic emissions of CO2 in all the four countries showed a significant increase(0.125 Pg C a^-1).Meanwhile the carbon uptake of terrestrial ecosystems increased at a growth rate of 0.003 Pg C a^-1.During the study period,the total anthropogenic carbon emissions of China and the United States accounted for 87.19% of the four countries while Russian terrestrial ecosystems had the strongest carbon absorption capacity,14.69 Pg C.Correspondingly,as of 2016,the cooling effect of terrestrial ecosystems is-0.013 W m^-2,which can offset 45.06% of the whole warming effects of anthropogenic carbon emissions,indicating that if the terrestrial ecosystems are not considered,the warming effect of anthropogenic carbon emissions will be significantly overestimated.Overall,the total anthropogenic carbon emissions of the four countries contributed 0.32 and 0.42 W m^-2 of global radiative forcing,respectively,relative to the CO2 concentration levels before 2000(initial year of this study) and before the Industrial Revolution.This study further explored the linear relationship between air temperature and radiative forcing.Compared with a single climate effect of anthropogenic or natural carbon emissions,the combined radiation forcing and the temperature change in the corresponding period had the highest consistency(30.3%).