Changes Of Major Greenhouse Gases In China And Their Contributions To Global Radiative Forcing

The assessment report of the Intergovernmental Panel on Climate Change pointed out that since the middle of the 20 th century,the greenhouse gas emissions caused by human socio-economic activities have caused the credibility of global warming as high as 95%.Atmospheric concentrations of major greenhouse gases?like CO₂,CH₄?have increased significantly.The accumulation of greenhouse gases in the atmosphere has caused changes in the global energy balance.Radiative forcing is a factor in measuring changes the inputoutput energy balance of the Earth-atmosphere system,and it also reflects the importance of the forcing factors in potential climate change.Therefore,systematically studying the dynamic changes of CO₂ and CH₄,and grasping the characteristics of their spatiotemporal changes and the changes in radiative forcing have important scientific significance and practical value for understanding the atmospheric environmental conditions and global climate change.Based on the Carbon Tracker 2017 CO₂ assimilation data set from 2000-2015 and the Carbon TrackerCH₄ data set from 2000-2010,the spatial and temporal distribution and dynamic changes of the main greenhouse gases CO₂ and CH₄ in the global and Chinese terrestrial anthropogenic and natural sources are firstly analyzed.Analysis.Then,the global and Chinese radiative forcing of CO₂ and CH₄ are compared and analyzed to measure the climate effects caused by changes in greenhouse gas concentrations.Finally,the relative contribution of CO₂ and CH₄ concentration changes of China's CO₂ and CH₄ during the study period to global climate change was quantified.The main conclusions are:?1?From 2000 to 2015,the average annual global CO₂ emissions from artificially generated fossil fuels fluctuated but still showed a significant upward trend.Natural factors play a role in absorbing CO₂,which can reduce some anthropogenic CO₂ emissions and the average annual net CO₂ emissions.Although the amount fluctuated,it still showed a significant upward trend.The change trend of global CO₂ emissions during the study period shows obvious spatial differences.China 's anthropogenic sources and net CO₂ emissions showed an increase in most regions between 2000 and 2015,while the area of natural factors that enhanced the ability to absorb CO₂ accounted for about 40% of the area,which was smaller than the area of weakened CO₂ ability to absorb,which showed an overall weakening trend.?2?From 2000 to 2010,total anthropogenic sources of CH₄ emissions accounted for 66% of global total CH₄ emissions and natural sources accounted for 34%.For many years,anthropogenic sources of CH₄ emissions generally showed higher emissions in the northern hemisphere than in the southern hemisphere and higher in the eastern hemisphere than in the western hemisphere feature.During the study period,except for the western region,China 's anthropogenic source CH₄ emissions showed an increasing trend,and wetland CH₄ emissions showed a decreasing trend.This area accounts for about 61% of the total area of the country,and net CH₄ emissions are increasing.Net CH₄ emissions in the western and northeastern regions are decreasing.?3?From 2000 to 2015,the global and Chinese anthropogenic CO₂ radiative forcing showed an upward trend,which was manifested as a climatic effect of rising temperatures.If purely anthropogenic emissions are taken into account,the warming effect of CO₂ will be overestimated.The cumulative anthropogenic and net CO₂ radiative forcing in the world between 2000 and 2015 were 0.57 and 0.39 W m-2,respectively,indicating that global natural sources have an impact on climate It reduced the cooling effect of 0.18 W m-2,which offset 30.96% of the anthropogenic radiative forcing;similarly,China's natural sources offset the 20.27% of the anthropogenic radiative forcing.?4?From 2000 to 2010,global and Chinese agricultural and waste,fossil fuel CH₄ caused radiative forcing fluctuations,while biomass burning CH₄ radiative forcing fluctuations were large,and agricultural and waste radiative forcing was much higher than Radiative forcing caused by other artificial sources of CH₄.The global wetland CH₄ radiative forcing has fluctuating changes,but the magnitude is not large.The overall change trend of CH₄ radiative forcing in Chinese wetlands is similar to the global trend,and both have a warming effect on the climate.The global and Chinese net radiative forcing of CH₄ between 2000 and 2010 showed a significant warming effect on the climate.?5?From 2000 to 2015,the contribution of Chinese anthropogenic CO₂ to global radiative forcing was 9.73%,but due to the carbon sink effect of terrestrial ecosystems,the net CO₂ contribution to the world was lower than that of anthropogenic,which was 7.93%.From 2000 to 2010,the contribution of Chinese anthropogenic CH₄ to global radiative forcing was 0.15%,the natural CH₄ was 0.02%,and the net CH₄ was 0.17%,which were all lower than the contribution of China's CO₂ to the world.At the same time,it was found that the contribution rate of radiative forcing caused by China's greenhouse gas emissions to global radiative forcing is much lower than the global proportion of China's greenhouse gas emissions,regardless of CO₂ or CH₄.