As an essential component of terrestrial carbon sinks,lake sediments store vast quantities of both organic carbon(OC)and inorganic carbon(IC).However,the spatiotemporal relationship between the OC and IC in sediments ...As an essential component of terrestrial carbon sinks,lake sediments store vast quantities of both organic carbon(OC)and inorganic carbon(IC).However,the spatiotemporal relationship between the OC and IC in sediments and their responses to climate change remains unclear,which hinders the comprehensive understanding of carbon dynamics in lake ecosystems.This study systematically analyzes the spatiotemporal dynamics of carbon burial across the Tibetan Plateau using surface sediments from 119 lakes and sediment cores from four representative lakes.Results show that OC burial dominates in humid and dry sub-humid zones,whereas IC burial prevails in arid and semi-arid regions.This distribution reflects the influences of lake and catchment productivity and water chemistry on OC and IC patterns.Sediment cores confirm that these factors have consistently affected lake carbon burial over the past century.Specifically,in humid and dry sub-humid zones,increased precipitation enhances watershed productivity and sedimentation,promoting coupled OC and IC burial.In arid and semi-arid regions,wind-driven dust supplies nutrients and alters water chemistry,also driving coupled OC and IC burial.Based on these findings,the carbon sink capacity of lake sediments on the Tibetan Plateau is projected to increase under the“warming and wetting”trend.展开更多
The existence of an intensifying shift in the East Asian summer monsoon(EASM)since~2000 years ago that differs from the decreasing trend of Northern Hemisphere summer insolation remains controversial.Therefore,we comp...The existence of an intensifying shift in the East Asian summer monsoon(EASM)since~2000 years ago that differs from the decreasing trend of Northern Hemisphere summer insolation remains controversial.Therefore,we compared and synthesized stalagmiteδ18O records from eastern China to clarify the EASM trend during this period.A total of 30 caveδ18O records that did not consistently indicate a depleted trend during 2-0 ka.Rather,they included increasing(14 caves),decreasing(8 caves),and non-significant(8 caves)trends.The spatially interpolated trends of caveδ18O suggested spatial differences among three subregions:North China(NC),decreasing trend(5 caves);Central-East China/Yangtze River Valley(CEC),increasing trend(17 caves);South China(SC),decreasing trend(8 caves).The caveδ18O evidence supports spatial differences in precipitation in eastern China that have been substantially demonstrated by observations and model simulations.The decreasingδ18O anomaly from NC and SC was associated with the decreasing sea surface temperature over Pacific Decadal Oscillation region and increasing South Oscillation Index.The increasing CECδ18O anomaly was linked to southward Intertropical Convergence Zone shift and decreasing solar irradiance.Consequently,EASM circulation is jointly forced by external and internal factors at various timescales.展开更多
Tropical cyclones(TCs)have profound impacts on socioeconomic conditions and pose substantial risks to lives and property.However,it is still unclear whether the multitimescale changes in TC activity over the past 2000...Tropical cyclones(TCs)have profound impacts on socioeconomic conditions and pose substantial risks to lives and property.However,it is still unclear whether the multitimescale changes in TC activity over the past 2000 years in the Northwestern Pacific(NWP)were regulated by Asian dust forcing.Here,we assessed the impact of Asian dust on TC activity using observational data and reconstructed records from the northern and southern NWP.Our correlation analysis of instrumental data from 1954 to 2017 reveals no significant relationship between observed TC activity and Asian dust forcing.Furthermore,we found a meridional dipole pattern of TC variation across the NWP in observations and reconstructions.These finding challenges current explanations that are based on the synchronous changes in TC activity and Asian dust forcing.Alternatively,we propose that the Western Pacific Subtropical High(WPSH)plays a crucial role in driving these meridional dipole patterns in TC variations,as supported by observations and reconstructions.The southwestward extension of an enhanced WPSH intensifies easterly flow,steering TCs westward along its southern edge.This leads to more TC activity in the southern NWP but less in the north,and vice versa when the WPSH is weakened.With the expected strengthening of the WPSH due to global warming,it is vital to consider its impact on NWP TC activity for effective risk-mitigation strategies.展开更多
Total organic carbon in lake surface sediments(STOC)constitutes a pivotal biogeochemical component within the critical interface of the global carbon cycle,where recently deposited organic matter undergoes burial or m...Total organic carbon in lake surface sediments(STOC)constitutes a pivotal biogeochemical component within the critical interface of the global carbon cycle,where recently deposited organic matter undergoes burial or mineralization,thereby playing a key role in carbon turnover and storage in inland water ecosystems.However,previous studies,constrained by local-scale observations and linear analytical methods,have not systematically characterized the global spatial patterns of STOC values and the mechanisms driving their variability.Here,by integrating STOC measurements from 89 lakes across the Tibetan Plateau with STOC data of 1070 lakes compiled based on a literature search,we present the first machine-learning-based assessment of global lake STOC patterns.Our results indicate that lake STOC concentrations peaked between 45°N and 70°N in the Northern Hemisphere,particularly in northern North America,whereas very high latitudes(>70°N)and mid-to low-latitude regions exhibited comparatively lower values.Structural equation modeling revealed that among basin characteristics,soil organic carbon and ice/snow cover were the strongest direct controls on lake STOC distribution,while temperature indirectly influenced STOC by modulating both variables.Although human activities affect STOC globally,their overall influence was modest.We conclude that temperature primarily governs the global spatial distribution of lake STOC concentrations through its influence on catchment processes.展开更多
There are debates regarding whether a wet and warm climate or a dry and cold climate dominated Holocene fire activity in northern China on the millennial timescale,and when human activities overtook climate change as ...There are debates regarding whether a wet and warm climate or a dry and cold climate dominated Holocene fire activity in northern China on the millennial timescale,and when human activities overtook climate change as the dominant control on fire occurrence in the region.Here we present a high-resolution fire history for the past~15,500 years from a sediment core in Dali Lake,located in the foothills of the Greater Hinggan Mountains,one of the areas of highest fire risk in China.The results demonstrate that fire activity was rare during the last deglaciation(~15,500–11,700 yr BP),gradually increased at the beginning of the Holocene,and reached its highest level during~9000–5000 yr BP,after which there was a decreasing trend.However,after~2000 yr BP this decreasing trend ended,and the most prominent feature is a peak in fire activity during the Medieval Warm Period(MWP).Overall,fire activity corresponded well to changes in the East Asian summer monsoon(EASM)precipitation on the millennial timescale during~15,500–2000 yr BP,but this relationship changed after~2000 yr BP.We propose that fire activity in northern China on the millennial timescale during~15,500–2000 yr BP was dominated by the biofuels reserve under the control of the EASM precipitation.In contrast,with the intensification of human activities after~2000 yr BP,human activity caused a~62%–73%increase in fire activity,which altered the fire-climate relationship that had previously prevailed in northern China.Our results indicate that a wet-warm climate(increased EASM intensity),rather than a dry-cold climate,was the dominant control on fire activity in northern China during 15,500–2000 yr BP on the millennial timescale,but that human activities played an important role in fire occurrence after~2000 yr BP.展开更多
Widespread aeolian deposits on the Tibetan Plateau(TP)have provided valuable palaeoclimatic information.However,the primary factors(e.g.,climate factors,human activity,and vegetation cover)controlling aeolian depositi...Widespread aeolian deposits on the Tibetan Plateau(TP)have provided valuable palaeoclimatic information.However,the primary factors(e.g.,climate factors,human activity,and vegetation cover)controlling aeolian deposition remain elusive.In this paper,we use a dataset that comprises new and published ages of Holocene aeolian sand and loess in the middle reaches of the Yarlung Zangbo River to identify the primary controlling factors and palaeoclimatic implications of aeolian deposition.Several intervals of enhanced aeolian accumulation centered at 8.5-7.8,6.4-5.8,4.5-4.0,3.1-1.8,and 0.9 ka are identified,generally consistent with regional low rainfall events and weak Indian summer monsoon(ISM).This suggests that regional wetness,dominated by the ISM,may play a key role in modulating dust emissions and aeolian deposition on centennial timescales.Our results show that on centennial-to millennial-scales,ISM activity can be reconstructed by non-continuous aeolian deposits in the monsoon dominated TP.展开更多
Physical geography,one of the branches of geography,is the basic discipline of geographic science.And it is the scientific foundation of ecology,environmental science and other related disciplines.Physical geography f...Physical geography,one of the branches of geography,is the basic discipline of geographic science.And it is the scientific foundation of ecology,environmental science and other related disciplines.Physical geography focuses on spatial characteristics,evolution and regional differentiation of the earth’s surface.In the new period of rapid development of social economy,and science and technology,physical geography is more closely and widely connected with human geography and,information geography.This paper analyzed the forming process of the physical geography,expressed sub-discipline structure of integrated physical geography,sectoral physical geography,human living-environment geography,and proposed the development strategy of physical geography and its sub-branch disciplines,key priority of development goals and directions in China.展开更多
基金National Natural Science Foundation of China,No.42225105,No.42201175The China Postdoctoral Science Foundation,No.2023M733605。
摘要As an essential component of terrestrial carbon sinks,lake sediments store vast quantities of both organic carbon(OC)and inorganic carbon(IC).However,the spatiotemporal relationship between the OC and IC in sediments and their responses to climate change remains unclear,which hinders the comprehensive understanding of carbon dynamics in lake ecosystems.This study systematically analyzes the spatiotemporal dynamics of carbon burial across the Tibetan Plateau using surface sediments from 119 lakes and sediment cores from four representative lakes.Results show that OC burial dominates in humid and dry sub-humid zones,whereas IC burial prevails in arid and semi-arid regions.This distribution reflects the influences of lake and catchment productivity and water chemistry on OC and IC patterns.Sediment cores confirm that these factors have consistently affected lake carbon burial over the past century.Specifically,in humid and dry sub-humid zones,increased precipitation enhances watershed productivity and sedimentation,promoting coupled OC and IC burial.In arid and semi-arid regions,wind-driven dust supplies nutrients and alters water chemistry,also driving coupled OC and IC burial.Based on these findings,the carbon sink capacity of lake sediments on the Tibetan Plateau is projected to increase under the“warming and wetting”trend.
基金National Natural Science Foundation of China,No.42225105National Natural Science Foundation of China,No.42471177,No.42201175,No.41901099+1 种基金The Open Foundation of MOE Key Laboratory of Western China's Environmental System,Lanzhou Universitythe Fundamental Research Funds for the Central Universities,No.lzujbky-2022-kb04。
摘要The existence of an intensifying shift in the East Asian summer monsoon(EASM)since~2000 years ago that differs from the decreasing trend of Northern Hemisphere summer insolation remains controversial.Therefore,we compared and synthesized stalagmiteδ18O records from eastern China to clarify the EASM trend during this period.A total of 30 caveδ18O records that did not consistently indicate a depleted trend during 2-0 ka.Rather,they included increasing(14 caves),decreasing(8 caves),and non-significant(8 caves)trends.The spatially interpolated trends of caveδ18O suggested spatial differences among three subregions:North China(NC),decreasing trend(5 caves);Central-East China/Yangtze River Valley(CEC),increasing trend(17 caves);South China(SC),decreasing trend(8 caves).The caveδ18O evidence supports spatial differences in precipitation in eastern China that have been substantially demonstrated by observations and model simulations.The decreasingδ18O anomaly from NC and SC was associated with the decreasing sea surface temperature over Pacific Decadal Oscillation region and increasing South Oscillation Index.The increasing CECδ18O anomaly was linked to southward Intertropical Convergence Zone shift and decreasing solar irradiance.Consequently,EASM circulation is jointly forced by external and internal factors at various timescales.
基金National Natural Science Foundation of China,No.42225105,No.42201176National Natural Science Foundation of China Basic Science Center for Tibetan Plateau Earth System Project(NSFC BSCTPES Project),No.41988101。
摘要Tropical cyclones(TCs)have profound impacts on socioeconomic conditions and pose substantial risks to lives and property.However,it is still unclear whether the multitimescale changes in TC activity over the past 2000 years in the Northwestern Pacific(NWP)were regulated by Asian dust forcing.Here,we assessed the impact of Asian dust on TC activity using observational data and reconstructed records from the northern and southern NWP.Our correlation analysis of instrumental data from 1954 to 2017 reveals no significant relationship between observed TC activity and Asian dust forcing.Furthermore,we found a meridional dipole pattern of TC variation across the NWP in observations and reconstructions.These finding challenges current explanations that are based on the synchronous changes in TC activity and Asian dust forcing.Alternatively,we propose that the Western Pacific Subtropical High(WPSH)plays a crucial role in driving these meridional dipole patterns in TC variations,as supported by observations and reconstructions.The southwestward extension of an enhanced WPSH intensifies easterly flow,steering TCs westward along its southern edge.This leads to more TC activity in the southern NWP but less in the north,and vice versa when the WPSH is weakened.With the expected strengthening of the WPSH due to global warming,it is vital to consider its impact on NWP TC activity for effective risk-mitigation strategies.
基金National Natural Science Foundation of China,No.42225105,No.42494821,No.42201175The China Postdoctoral Science Foundation,No.2023M733605。
摘要Total organic carbon in lake surface sediments(STOC)constitutes a pivotal biogeochemical component within the critical interface of the global carbon cycle,where recently deposited organic matter undergoes burial or mineralization,thereby playing a key role in carbon turnover and storage in inland water ecosystems.However,previous studies,constrained by local-scale observations and linear analytical methods,have not systematically characterized the global spatial patterns of STOC values and the mechanisms driving their variability.Here,by integrating STOC measurements from 89 lakes across the Tibetan Plateau with STOC data of 1070 lakes compiled based on a literature search,we present the first machine-learning-based assessment of global lake STOC patterns.Our results indicate that lake STOC concentrations peaked between 45°N and 70°N in the Northern Hemisphere,particularly in northern North America,whereas very high latitudes(>70°N)and mid-to low-latitude regions exhibited comparatively lower values.Structural equation modeling revealed that among basin characteristics,soil organic carbon and ice/snow cover were the strongest direct controls on lake STOC distribution,while temperature indirectly influenced STOC by modulating both variables.Although human activities affect STOC globally,their overall influence was modest.We conclude that temperature primarily governs the global spatial distribution of lake STOC concentrations through its influence on catchment processes.
基金National Natural Science Foundation of China,No.41790421。
摘要There are debates regarding whether a wet and warm climate or a dry and cold climate dominated Holocene fire activity in northern China on the millennial timescale,and when human activities overtook climate change as the dominant control on fire occurrence in the region.Here we present a high-resolution fire history for the past~15,500 years from a sediment core in Dali Lake,located in the foothills of the Greater Hinggan Mountains,one of the areas of highest fire risk in China.The results demonstrate that fire activity was rare during the last deglaciation(~15,500–11,700 yr BP),gradually increased at the beginning of the Holocene,and reached its highest level during~9000–5000 yr BP,after which there was a decreasing trend.However,after~2000 yr BP this decreasing trend ended,and the most prominent feature is a peak in fire activity during the Medieval Warm Period(MWP).Overall,fire activity corresponded well to changes in the East Asian summer monsoon(EASM)precipitation on the millennial timescale during~15,500–2000 yr BP,but this relationship changed after~2000 yr BP.We propose that fire activity in northern China on the millennial timescale during~15,500–2000 yr BP was dominated by the biofuels reserve under the control of the EASM precipitation.In contrast,with the intensification of human activities after~2000 yr BP,human activity caused a~62%–73%increase in fire activity,which altered the fire-climate relationship that had previously prevailed in northern China.Our results indicate that a wet-warm climate(increased EASM intensity),rather than a dry-cold climate,was the dominant control on fire activity in northern China during 15,500–2000 yr BP on the millennial timescale,but that human activities played an important role in fire occurrence after~2000 yr BP.
基金National Natural Science Foundation of China,No.41601191,No.41871070,No.41877460National Basic Research Program of China,No.2013CB956001Special Researcher Project of Henan Province。
摘要Widespread aeolian deposits on the Tibetan Plateau(TP)have provided valuable palaeoclimatic information.However,the primary factors(e.g.,climate factors,human activity,and vegetation cover)controlling aeolian deposition remain elusive.In this paper,we use a dataset that comprises new and published ages of Holocene aeolian sand and loess in the middle reaches of the Yarlung Zangbo River to identify the primary controlling factors and palaeoclimatic implications of aeolian deposition.Several intervals of enhanced aeolian accumulation centered at 8.5-7.8,6.4-5.8,4.5-4.0,3.1-1.8,and 0.9 ka are identified,generally consistent with regional low rainfall events and weak Indian summer monsoon(ISM).This suggests that regional wetness,dominated by the ISM,may play a key role in modulating dust emissions and aeolian deposition on centennial timescales.Our results show that on centennial-to millennial-scales,ISM activity can be reconstructed by non-continuous aeolian deposits in the monsoon dominated TP.
基金National Natural Science Foundation of China,No.41530749,No.41842050。
摘要Physical geography,one of the branches of geography,is the basic discipline of geographic science.And it is the scientific foundation of ecology,environmental science and other related disciplines.Physical geography focuses on spatial characteristics,evolution and regional differentiation of the earth’s surface.In the new period of rapid development of social economy,and science and technology,physical geography is more closely and widely connected with human geography and,information geography.This paper analyzed the forming process of the physical geography,expressed sub-discipline structure of integrated physical geography,sectoral physical geography,human living-environment geography,and proposed the development strategy of physical geography and its sub-branch disciplines,key priority of development goals and directions in China.