Detection And Quantification Of Anthropogenic Influence Over Global Surface Air Temperature Warming

Since the Industrial Revolution,the global climate has been significantly warming,and the warming of the northern hemisphere has reached an unprecedented level in recent decades.The Arctic,Tibetan Plateau as well as arid and semi-arid areas are sensitive regions to climate change,and human activities have intensified the abnormal warming in these regions.The abnormal warming not only changes the local climate environment,but also causes global extreme high temperature,drought,flood and other disasters,posing a serious threat to human survival as well as social and economic development.Therefore,in the context of climate warming,determining the extent to which natural variability and anthropogenic forcings contribute to temperature change over globe and sensitive regions is critical for developing mitigation policies and adaptation plans.Based on the long-term memory of the climate system,this paper quantitatively evaluates the anthropogenic influence of abnormal warming by constructing a probability distribution function.This method can effectively separate the anthropogenic influence of surface air temperature changes observed in global and sensitive regions without relying on numerical models,and determine the contribution of anthropogenic forcing to the warming of different regions.It provides a new method and a new perspective for the study of attribution of long-term global climate trends.The main research contents and conclusions are summarized as follows:(1)Detection and quantification of anthropogenic influence over global land surface air temperature increaseFrom 1951 to 2015,the African continent showed the most pronounced warming,which was dominated by anthropogenic trends.The relative temperature change in northern South America is mainly influenced by natural variability(with the exception of Brazil),and the magnitude of warming is second only to Africa.The warming in Eurasia and Australia is weaker than that in Africa and northern South America,the warming in northwestern Europe and northern Australia is mainly due to natural variability,and the warming in Central and northern East Asia is more influenced by anthropogenically-driven trends.It is worth noting that in North America,anthropogenically-driven trends had a greater impact on the southwestern coast of the United States,northeastern Canada,and northern Greenland.In terms of the extent of anthropogenic influence,the overall anthropogenically-driven trend was larger in Brazil,much of Africa,Saudi Arabia,India,Singapore and the Philippines.The anthropogenically-driven warming in Eurasia and North America at middle and high latitudes is generally larger,indicating that these regions are most sensitive to anthropogenic forcings.Minimum anthropogenically-driven warming in northern Greenland,eastern Africa,and parts of mid-high latitudes of Eurasia contributed more than 80% of the observed warming.In terms of time evolution,anthropogenic influences in Central Asia and Siberia became significant at the latest.From the perspective of influence degree,the anthropogenically-driven trend is the most significant in North Africa,followed by western Brazil.In these two regions,the anthropogenically-driven trend grows the fastest over time.(2)Detection and quantification of anthropogenic influence in Arctic amplified warmingFrom 1979 to 2017,the Arctic coast of the Siberian Great Plains,from the Barents Sea to the Kara Sea and eastward to the Bering Strait,has been warming significantly,with the East Siberian Sea and the Kara Sea coastal areas mainly caused by anthropogenically-driven trends,and the Laptev Sea and Barents Sea mainly caused by natural variability.The minimum anthropogenically-driven warming in most areas of the Arctic Ocean is more than 2°C,especially in the Kara Sea,which is up to 4°C.The Kara Sea is sensitive to anthropogenic forcing.The minimum anthropogenic contributions exceed 60% in most parts of the Arctic Circle and was more than 80% in(75–90° N,150–180° W).In the 140°E-135°W region of the Arctic,the total linear trend is the greatest,and the anthropogenically-driven linear trend is also the greatest,accounting for 85% of the measured total linear trend.The overall linear trend of 0 ～135°W was the smallest,and the anthropogenically-driven linear trend was also the smallest,accounting for 59%.Meanwhile,the anthropogenically-driven trend changes most rapidly over time in this region(0 ～ 135°W,60 ～ 90°N).(3)Detection and quantification of anthropogenic influence of rapid warming over the Tibetan PlateauAnthropogenically-driven trends have intensified regional warming and played a leading role in the rapid warming of the Tibetan Plateau.Especially in the centralwestern regions,anthropogenically-driven warming was greater than 1.2°C during1980-2018.Thus,anthropogenic forcing contributes more than 60% of the total warming(～ 2°C).At the same time,the pronounced warming over the Tibetan Plateau is the result of the slight variation of dynamic temperature on the whole Plateau and the enhanced warming of thermodynamic temperature on a regional scale.The variation of dynamic temperature is mainly attributed to natural variability.The increase in thermodynamic temperature is caused by both natural variability and anthropogenic forcing.The increase of thermodynamic temperature over the southwestern Tibetan Plateau during 1980-2018 was mainly due to anthropogenic forcing,and the corresponding anthropogenically-driven warming was more than 1.4°C.The contribution of anthropogenic forcing to thermodynamic temperature is more than 50%in most areas of Tibetan Plateau,especially over 70% in the southwest.From the regional average of the Tibetan Plateau,anthropogenic effects are significant on raw and thermodynamic temperature.During 1980-2018,the minimum anthropogenicallydriven warming of the row temperature reached 0.97°C,accounting for 58% of the total observed warming.The minimum anthropogenically-driven warming of the thermodynamic component is 0.74°C,which contributes 42% to the thermodynamic total warming.Therefore,human activities are primarily responsible for thermodynamic temperature increase.In other words,anthropogenic forcing affects the warming of the Tibetan Plateau mainly through thermal effects.(4)Detection and quantification of anthropogenic influence of air temperature increase in ChinaIn the temperature records of 160 stations in China,anthropogenically-driven trends and warming were larger in Northeast China,Inner Mongolia and the northern Shanxi.According to the spatial evolution of the significant warming regions over different decades,anthropogenically-driven warming took the lead in North China and Northeast China,and then gradually expanded to the south and west.From 1966 to2001,most regions of China showed significant anthropogenically-driven warming.From 1971 to 2006,the significant areas of anthropogenically-driven warming in northeast China and northeastern Inner Mongolia began to decrease gradually,while the significant areas of anthropogenic warming in southwest China began to increase gradually.The significant warming areas from 1976 to 2011 were the largest.From1981 to 2016,the significant warming sites were mainly concentrated in the Yellow River Basin,the Yangtze River Basin and the area between the two basins as well as southern China.In conclusion,the significant areas of anthropogenic warming in China have significant interdecadal changes in both time and space.