Neolithic site sections, natural sections and other proxy indicators like paleotrees and peat are collected for further understanding the environmental changes during the past 10,000 years in the Yangtze Delta region....Neolithic site sections, natural sections and other proxy indicators like paleotrees and peat are collected for further understanding the environmental changes during the past 10,000 years in the Yangtze Delta region. The results indicate that cultural interruption in the Yangtze Delta was the result of water expansion induced by climatic changes like more precipitation. For fi＇agile human mitigation to the natural hazards in the Neolithic cultural period, environmental changes usually exerted tremendous influences on human activities, havocking the human civilization, which is meaningful for human mitigation to natural hazards under the present global warming. At the same time, some uncertainties in reconstruction ofoaleo-environmental changes were discussed in the text.展开更多
The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in u...The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM.(1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr(thousand years) periodicity, while the cave oxygen-isotope(δ18 O) records reveal periodicity in an almost pure precession band(~20 kyr periodicity)—the "Chinese 100 kyr problem".(2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation(NHSI), whereas the Asian cave δ18 O records follow NHSI without a significant lag—a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox".展开更多
Whether the Atlantic Meridional Overturning Circulation(AMOC),one of the most vital tipping elements in the Earth’s cli-mate system with far-reaching effects on interhemispheric heat distributions,the carbon cycles,a...Whether the Atlantic Meridional Overturning Circulation(AMOC),one of the most vital tipping elements in the Earth’s cli-mate system with far-reaching effects on interhemispheric heat distributions,the carbon cycles,and a cascade series of hydrocli-matic changes worldwide,is approaching a tipping point has become an increasingly urgent concern[1-4].Climate proxy records arguably suggest that the AMOC is currently at its weakest state over the last millennium,with a marked AMOC weakening trend evident between 1870 and 2020 C.E.[3].A recent physics-based analysis of early warning signals even suggests that an AMOC collapse could occur as early as one year from 2024 C.E.[2].Nevertheless,the IPCC AR6,based on simulations from the Cli-mate Model Intercomparison Project(CMIP),quotes that an AMOC collapse in the 21st century is unlikely(Fig.S1 online)[2].This data-model discrepancy suggests unaccounted-for factors have been influencing AMOC[1].While the AMOC collapse would pose severe cascading impacts on global climate disruption,consider-able uncertainty remains regarding whether and when such an AMOC collapse is coming[2,4,5].One approach to address this challenge lies in a precise comparison of the ongoing AMOC weak-ening with their analogous episodes preserved in paleoclimate records-putting the AMOC weakening into context with a series of presumable AMOC collapse scenarios inferred from Greenland ice core oxygen isotope(d18 O,mainly a proxy of Greenland tem-perature)records[6-8](Fig.S2b online).展开更多
基金Key Project of the National Natural Science Foundation of China, No.90411015 Foundation of Nanjing Institute of Geography and Limnology, CAS, No.S260018+2 种基金 National Natural Science Foundation of China, No.40271103 Open Foundation of the State Key Laboratory of Loess and Quaternary Geology from the Institute of Earth Environment, CAS, No. SKLLQG0503 Physical Geography of "985" Item and Foundation of Modern Analyses Center of Nanjing University
文摘Neolithic site sections, natural sections and other proxy indicators like paleotrees and peat are collected for further understanding the environmental changes during the past 10,000 years in the Yangtze Delta region. The results indicate that cultural interruption in the Yangtze Delta was the result of water expansion induced by climatic changes like more precipitation. For fi＇agile human mitigation to the natural hazards in the Neolithic cultural period, environmental changes usually exerted tremendous influences on human activities, havocking the human civilization, which is meaningful for human mitigation to natural hazards under the present global warming. At the same time, some uncertainties in reconstruction ofoaleo-environmental changes were discussed in the text.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41888101 & 41731174)。
文摘The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM.(1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr(thousand years) periodicity, while the cave oxygen-isotope(δ18 O) records reveal periodicity in an almost pure precession band(~20 kyr periodicity)—the "Chinese 100 kyr problem".(2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation(NHSI), whereas the Asian cave δ18 O records follow NHSI without a significant lag—a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox".
基金supported by the State Key Laboratory of Loess Science(SKLLQGZR2401)the National Natural Science Foundation of China(42372218,42488201,and 423B2204)Guangxi Key Science and Technology Innovation Base on Karst Dynamics(KDL&Guangxi202005)。
文摘Whether the Atlantic Meridional Overturning Circulation(AMOC),one of the most vital tipping elements in the Earth’s cli-mate system with far-reaching effects on interhemispheric heat distributions,the carbon cycles,and a cascade series of hydrocli-matic changes worldwide,is approaching a tipping point has become an increasingly urgent concern[1-4].Climate proxy records arguably suggest that the AMOC is currently at its weakest state over the last millennium,with a marked AMOC weakening trend evident between 1870 and 2020 C.E.[3].A recent physics-based analysis of early warning signals even suggests that an AMOC collapse could occur as early as one year from 2024 C.E.[2].Nevertheless,the IPCC AR6,based on simulations from the Cli-mate Model Intercomparison Project(CMIP),quotes that an AMOC collapse in the 21st century is unlikely(Fig.S1 online)[2].This data-model discrepancy suggests unaccounted-for factors have been influencing AMOC[1].While the AMOC collapse would pose severe cascading impacts on global climate disruption,consider-able uncertainty remains regarding whether and when such an AMOC collapse is coming[2,4,5].One approach to address this challenge lies in a precise comparison of the ongoing AMOC weak-ening with their analogous episodes preserved in paleoclimate records-putting the AMOC weakening into context with a series of presumable AMOC collapse scenarios inferred from Greenland ice core oxygen isotope(d18 O,mainly a proxy of Greenland tem-perature)records[6-8](Fig.S2b online).
