Global warming is causing the Tibetan permafrost to degrade, as evidenced by rising ground temperatures, thicker active layer thickness, thinner permafrost layer, and melting underground ice, etc.(Ran et al., 2018;Wan...Global warming is causing the Tibetan permafrost to degrade, as evidenced by rising ground temperatures, thicker active layer thickness, thinner permafrost layer, and melting underground ice, etc.(Ran et al., 2018;Wang et al., 2020).The degradation of permafrost not only profoundly alters the carbon cycling processes in high-altitude ecosystems,thereby influencing the regional climate system, but also affects landscape hydrological connectivity。展开更多
Carbon cycling in terrestrial ecosystems is an important factor that affects the level and accumulation rate of global atmospheric greenhouse gases and determines the stability of the global climate.From 2010 to 2019,...Carbon cycling in terrestrial ecosystems is an important factor that affects the level and accumulation rate of global atmospheric greenhouse gases and determines the stability of the global climate.From 2010 to 2019,31%of CO_(2) emissions caused by human activities were absorbed by vegetation in terrestrial ecosystems and 23%by the ocean,while the remaining 46%accumulated in the atmosphere.However,as the climate continues to warm。展开更多
The contemporary carbon balance over the Tibetan Plateau is highly uncertain with a ten-fold difference between various estimates.In a warming world,the potential exists for a large carbon release from its permafrost ...The contemporary carbon balance over the Tibetan Plateau is highly uncertain with a ten-fold difference between various estimates.In a warming world,the potential exists for a large carbon release from its permafrost which could compromise China’s 2060 carbon-neutral goal.Here,we used a satellite-and inventory-based approach,ecosystem models,and atmospheric inversions to estimate that the carbon sink was 33.12–37.84 TgC yr^(–1)during 2000–2015.The carbon sink induced by climate change and increasing CO_(2) levels largely overcompensated for a livestock grazing-induced carbon source of 0.38TgC yr^(-1).By 2060,the carbon sink is projected to increase by 38.3–74.5% under moderate to high emissions scenarios,with the enhanced vegetation carbon uptake outweighing the warming-induced permafrost carbon release.The restoration of degraded grassland could sequestrate an additional 9.06 TgC yr^(-1),leading to a total carbon sink of 57.78–70.52 TgC yr^(-1).We conclude that the Tibetan Plateau’s ecosystems absorbed two-and-a-half times the amount of its cumulative fossil CO_(2) emissions during 2000–2015 and that their carbon sinks will almost double in strength in the future,helping to achieve China’s pledge to become carbon neutral by 2060.展开更多
Satellite carbon dioxide(CO_(2))retrievals provide important constraints on surface carbon fluxes in regions that are undersampled by global in situ networks.In this study,we developed an atmospheric inversion system ...Satellite carbon dioxide(CO_(2))retrievals provide important constraints on surface carbon fluxes in regions that are undersampled by global in situ networks.In this study,we developed an atmospheric inversion system to infer CO_(2)sources and sinks from Orbiting Carbon Observatory-2(OCO-2)column CO_(2)retrievals during 2015–2019,and compared our estimates to five other state-of-the-art inversions.By assimilating satellite CO_(2)retrievals in the inversion,the global net terrestrial carbon sink(net biome productivity,NBP)was found to be 1.03±0.39 petagrams of carbon per year(Pg C yr^(-1));this estimate is lower than the sink estimate of 1.46–2.52 Pg C yr^(-1),obtained using surface-based inversions.We estimated a weak northern uptake of 1.30 Pg C yr-1and weak tropical release of-0.26 Pg C yr^(-1),consistent with previous reports.By contrast,the other inversions showed a strong northern uptake(1.44–2.78 Pg C yr-1),but diverging tropical carbon fluxes,from a sink of 0.77 Pg C yr^(-1) to a source of-1.26 Pg C yr^(-1).During the 2015–2016 El Ni?o event,the tropical land biosphere was mainly responsible for a higher global CO_(2)growth rate.Anomalously high carbon uptake in the northern extratropics,consistent with concurrent extreme Northern Hemisphere greening,partially offset the tropical carbon losses.This anomalously high carbon uptake was not always found in surface-based inversions,resulting in a larger global carbon release in the other inversions.Thus,our satellite constraint refines the current understanding of flux partitioning between northern and tropical terrestrial regions,and suggests that the northern extratropics acted as anomalous high CO_(2)sinks in response to the 2015–2016 El Nino event.展开更多
The Chinese government has made a strategic decision to reach ‘carbon neutrality' before 2060. China's terrestrial ecosystem carbon sink is currently offsetting 7–15% of national anthropogenic emissions and ...The Chinese government has made a strategic decision to reach ‘carbon neutrality' before 2060. China's terrestrial ecosystem carbon sink is currently offsetting 7–15% of national anthropogenic emissions and has received widespread attention regarding its role in the ‘carbon neutrality' strategy. We provide perspectives on this question by inferring from the fundamental principles of terrestrial ecosystem carbon cycles. We first elucidate the basic ecological theory that, over the long-term succession of ecosystem without regenerative disturbances, the carbon sink of a given ecosystem will inevitably approach zero as the ecosystem reaches its equilibrium state or climax. In this sense, we argue that the currently observed global terrestrial carbon sink largely emerges from the processes of carbon uptake and release of ecosystem responding to environmental changes and, as such, the carbon sink is never an intrinsic ecosystem function. We further elaborate on the long-term effects of atmospheric CO_(2) changes and afforestation on China's terrestrial carbon sink: the enhancement of the terrestrial carbon sink by the CO_(2) fertilization effect will diminish as the growth of the atmospheric CO_(2) slows down, or completely stops, depending on international efforts to combat climate change, and carbon sinks induced by ecological engineering, such as afforestation, will also decline as forest ecosystems become mature and reach their late-successional stage. We conclude that terrestrial ecosystems have nonetheless an important role to play to gain time for industrial emission reduction during the implementation of the ‘carbon neutrality' strategy. In addition, science-based ecological engineering measures including afforestation and forest management could be used to elongate the time of ecosystem carbon sink service. We propose that the terrestrial carbon sink pathway should be optimized, by addressing the questions of ‘when' and ‘where' to plan afforestation projects, in order to effectively strengthen the terrestrial ecosystem carbon sink and maximize its contribution to the realization of the ‘carbon neutrality' strategy.展开更多
The Tibetan Plateau(TP)and Arctic permafrost constitute two large reservoirs of organic carbon,but processes which control carbon accumulation within the surface soil layer of these areas would differ due to the inter...The Tibetan Plateau(TP)and Arctic permafrost constitute two large reservoirs of organic carbon,but processes which control carbon accumulation within the surface soil layer of these areas would differ due to the interplay of climate,soil and vegetation type.Here,we synthesized currently available soil carbon data to show that mean organic carbon density in the topsoil(0-10 cm)in TP grassland(3.12±0.52 kg C m^(-2))is less than half of that in Arctic tundra(6.70±1.94 kg C m^(-2)).Such difference is primarily attributed to their difference in radiocarbon-inferred soil carbon turnover times(547 years for TP grassland versus 1609 years for Arctic tundra)rather than to their marginal difference in topsoil carbon inputs.Our findings highlight the importance of improving regional-specific soil carbon turnover and its controlling mechanisms across permafrost affected zones in ecosystem models to fully represent carbon-climate feedback.展开更多
Soil heterotrophic respiration(Rh)is the flux of CO2 that microbes and soil fauna release to the atmosphere by extracting the energy of organic molecules that they break down[1].Rh closes the terrestrial carbon cycle ...Soil heterotrophic respiration(Rh)is the flux of CO2 that microbes and soil fauna release to the atmosphere by extracting the energy of organic molecules that they break down[1].Rh closes the terrestrial carbon cycle by recycling more than 70%of the annual total fixed carbon to the atmosphere per year so that it can be reused by plants for photosynthesis[2].Rh plays a key role in regulating the changes in atmospheric CO2 concentrations as well as the consequential climate feedbacks[3,4].However,global Rh estimates suffer from large uncertainty.The simulated global Rh value ranges from 30 to 64 Pg C a-1 by MsTMIP models[5],from 47 to 72 Pg C a-1 by Trendy models[6],and from 42 to 73 Pg C a-1 by CMIP5 models[1].High spatial heterogeneity and the close contingency of soil decomposition on environmental changes,such as temperature and soil moisture,may be a response to such great unpredictability[7].Rh is highly transient and variable at diurnal,seasonal and multiyear scales.Short-term observations and limited in situ measurements,as well as low representativeness in many key regions with high soil carbon stocks and difficult accessibilities,such as the northern circumpolar permafrost region and high-altitude Tibetan region,make Rh the most unpredictable process in land-carbon cycle models[8].Accurate estimates of Rh at regional and global scales are thus imperative to quantify the land carbon sink,to evaluate land-carbon cycle models and to define baselines for climate change mitigation efforts.展开更多
This paper studies the benefit of the blockchain food traceability system(BFTS).Based on game theory and the willingness-to-pay model,pricing models are formulated considering important factors like the proportion of ...This paper studies the benefit of the blockchain food traceability system(BFTS).Based on game theory and the willingness-to-pay model,pricing models are formulated considering important factors like the proportion of consumer with high expertise in traceability,risk attitude to doubtful traceability information and perceived convenience of traceability information checking.By compared the optimal total welfare under the BFTS and that under the traditional food traceability system in valuation analysis,conditions where applying the BFTS is more valuable than applying the TFTS are figured out.Finally,insightful management implications are given.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program (Grant No. 2022QZKK0101)the West Light Foundation of the Chinese Academy of Sciences (Grant No. xbzg-zdsys-202202)the Science and Technology Major Project of Xizang Autonomous Region of China (XZ202201ZD0005G04)。
文摘Global warming is causing the Tibetan permafrost to degrade, as evidenced by rising ground temperatures, thicker active layer thickness, thinner permafrost layer, and melting underground ice, etc.(Ran et al., 2018;Wang et al., 2020).The degradation of permafrost not only profoundly alters the carbon cycling processes in high-altitude ecosystems,thereby influencing the regional climate system, but also affects landscape hydrological connectivity。
基金supported by the National Natural Science Foundation of China(42022004,41901085,and 41988101)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0606)。
文摘Carbon cycling in terrestrial ecosystems is an important factor that affects the level and accumulation rate of global atmospheric greenhouse gases and determines the stability of the global climate.From 2010 to 2019,31%of CO_(2) emissions caused by human activities were absorbed by vegetation in terrestrial ecosystems and 23%by the ocean,while the remaining 46%accumulated in the atmosphere.However,as the climate continues to warm。
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Programme (Grant Nos.2019QZKK0606,2022QZKK0101)the National Natural Science Foundation of China (Grant Nos.41901136,41922004,41871104)the Science and Technology Major Project of Tibetan Autonomous Region of China (Grant No.XZ202201ZD0005G01)。
文摘The contemporary carbon balance over the Tibetan Plateau is highly uncertain with a ten-fold difference between various estimates.In a warming world,the potential exists for a large carbon release from its permafrost which could compromise China’s 2060 carbon-neutral goal.Here,we used a satellite-and inventory-based approach,ecosystem models,and atmospheric inversions to estimate that the carbon sink was 33.12–37.84 TgC yr^(–1)during 2000–2015.The carbon sink induced by climate change and increasing CO_(2) levels largely overcompensated for a livestock grazing-induced carbon source of 0.38TgC yr^(-1).By 2060,the carbon sink is projected to increase by 38.3–74.5% under moderate to high emissions scenarios,with the enhanced vegetation carbon uptake outweighing the warming-induced permafrost carbon release.The restoration of degraded grassland could sequestrate an additional 9.06 TgC yr^(-1),leading to a total carbon sink of 57.78–70.52 TgC yr^(-1).We conclude that the Tibetan Plateau’s ecosystems absorbed two-and-a-half times the amount of its cumulative fossil CO_(2) emissions during 2000–2015 and that their carbon sinks will almost double in strength in the future,helping to achieve China’s pledge to become carbon neutral by 2060.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(2022QZKK0101)the National Natural Science Foundation of China(41988101,42001104,and 41975140)+1 种基金the National Key Scientific and Technological Infrastructure Project“Earth System Science Numerical Simulator Facility”(Earth Lab,201715003471104355)the Innovation Program for Young Scholars of TPESER(TPESER-QNCX2022ZD-01)。
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(2022QZKK0101)the National Natural Science Foundation of China(Grant Nos.41975140&42105150)。
文摘Satellite carbon dioxide(CO_(2))retrievals provide important constraints on surface carbon fluxes in regions that are undersampled by global in situ networks.In this study,we developed an atmospheric inversion system to infer CO_(2)sources and sinks from Orbiting Carbon Observatory-2(OCO-2)column CO_(2)retrievals during 2015–2019,and compared our estimates to five other state-of-the-art inversions.By assimilating satellite CO_(2)retrievals in the inversion,the global net terrestrial carbon sink(net biome productivity,NBP)was found to be 1.03±0.39 petagrams of carbon per year(Pg C yr^(-1));this estimate is lower than the sink estimate of 1.46–2.52 Pg C yr^(-1),obtained using surface-based inversions.We estimated a weak northern uptake of 1.30 Pg C yr-1and weak tropical release of-0.26 Pg C yr^(-1),consistent with previous reports.By contrast,the other inversions showed a strong northern uptake(1.44–2.78 Pg C yr-1),but diverging tropical carbon fluxes,from a sink of 0.77 Pg C yr^(-1) to a source of-1.26 Pg C yr^(-1).During the 2015–2016 El Ni?o event,the tropical land biosphere was mainly responsible for a higher global CO_(2)growth rate.Anomalously high carbon uptake in the northern extratropics,consistent with concurrent extreme Northern Hemisphere greening,partially offset the tropical carbon losses.This anomalously high carbon uptake was not always found in surface-based inversions,resulting in a larger global carbon release in the other inversions.Thus,our satellite constraint refines the current understanding of flux partitioning between northern and tropical terrestrial regions,and suggests that the northern extratropics acted as anomalous high CO_(2)sinks in response to the 2015–2016 El Nino event.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program (Grant No. 2019QZKK0405)the National Science Foundation (Grant Nos. 41988101 and 41971132)。
文摘The Chinese government has made a strategic decision to reach ‘carbon neutrality' before 2060. China's terrestrial ecosystem carbon sink is currently offsetting 7–15% of national anthropogenic emissions and has received widespread attention regarding its role in the ‘carbon neutrality' strategy. We provide perspectives on this question by inferring from the fundamental principles of terrestrial ecosystem carbon cycles. We first elucidate the basic ecological theory that, over the long-term succession of ecosystem without regenerative disturbances, the carbon sink of a given ecosystem will inevitably approach zero as the ecosystem reaches its equilibrium state or climax. In this sense, we argue that the currently observed global terrestrial carbon sink largely emerges from the processes of carbon uptake and release of ecosystem responding to environmental changes and, as such, the carbon sink is never an intrinsic ecosystem function. We further elaborate on the long-term effects of atmospheric CO_(2) changes and afforestation on China's terrestrial carbon sink: the enhancement of the terrestrial carbon sink by the CO_(2) fertilization effect will diminish as the growth of the atmospheric CO_(2) slows down, or completely stops, depending on international efforts to combat climate change, and carbon sinks induced by ecological engineering, such as afforestation, will also decline as forest ecosystems become mature and reach their late-successional stage. We conclude that terrestrial ecosystems have nonetheless an important role to play to gain time for industrial emission reduction during the implementation of the ‘carbon neutrality' strategy. In addition, science-based ecological engineering measures including afforestation and forest management could be used to elongate the time of ecosystem carbon sink service. We propose that the terrestrial carbon sink pathway should be optimized, by addressing the questions of ‘when' and ‘where' to plan afforestation projects, in order to effectively strengthen the terrestrial ecosystem carbon sink and maximize its contribution to the realization of the ‘carbon neutrality' strategy.
基金This work was supported by Preliminary Research on Three Poles Environment and Climate Change(2019YFC1509103)the National Natural Science Foundation of China(41861134036 and 41922004)+1 种基金the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0606)the Strategic Priority Research Program(A)of the Chinese Academy of Sciences(XDA19070303 and XDA20050101).
文摘The Tibetan Plateau(TP)and Arctic permafrost constitute two large reservoirs of organic carbon,but processes which control carbon accumulation within the surface soil layer of these areas would differ due to the interplay of climate,soil and vegetation type.Here,we synthesized currently available soil carbon data to show that mean organic carbon density in the topsoil(0-10 cm)in TP grassland(3.12±0.52 kg C m^(-2))is less than half of that in Arctic tundra(6.70±1.94 kg C m^(-2)).Such difference is primarily attributed to their difference in radiocarbon-inferred soil carbon turnover times(547 years for TP grassland versus 1609 years for Arctic tundra)rather than to their marginal difference in topsoil carbon inputs.Our findings highlight the importance of improving regional-specific soil carbon turnover and its controlling mechanisms across permafrost affected zones in ecosystem models to fully represent carbon-climate feedback.
基金the National Natural Science Foun-dation of China(42022004 and 41901085)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0606)。
文摘Soil heterotrophic respiration(Rh)is the flux of CO2 that microbes and soil fauna release to the atmosphere by extracting the energy of organic molecules that they break down[1].Rh closes the terrestrial carbon cycle by recycling more than 70%of the annual total fixed carbon to the atmosphere per year so that it can be reused by plants for photosynthesis[2].Rh plays a key role in regulating the changes in atmospheric CO2 concentrations as well as the consequential climate feedbacks[3,4].However,global Rh estimates suffer from large uncertainty.The simulated global Rh value ranges from 30 to 64 Pg C a-1 by MsTMIP models[5],from 47 to 72 Pg C a-1 by Trendy models[6],and from 42 to 73 Pg C a-1 by CMIP5 models[1].High spatial heterogeneity and the close contingency of soil decomposition on environmental changes,such as temperature and soil moisture,may be a response to such great unpredictability[7].Rh is highly transient and variable at diurnal,seasonal and multiyear scales.Short-term observations and limited in situ measurements,as well as low representativeness in many key regions with high soil carbon stocks and difficult accessibilities,such as the northern circumpolar permafrost region and high-altitude Tibetan region,make Rh the most unpredictable process in land-carbon cycle models[8].Accurate estimates of Rh at regional and global scales are thus imperative to quantify the land carbon sink,to evaluate land-carbon cycle models and to define baselines for climate change mitigation efforts.
文摘This paper studies the benefit of the blockchain food traceability system(BFTS).Based on game theory and the willingness-to-pay model,pricing models are formulated considering important factors like the proportion of consumer with high expertise in traceability,risk attitude to doubtful traceability information and perceived convenience of traceability information checking.By compared the optimal total welfare under the BFTS and that under the traditional food traceability system in valuation analysis,conditions where applying the BFTS is more valuable than applying the TFTS are figured out.Finally,insightful management implications are given.
