Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions,in order to further understand the mechanisms of past climate variability.Yet,the global c...Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions,in order to further understand the mechanisms of past climate variability.Yet,the global coverage of existing temperature records is still limited,especially for some key regions like the Tibetan Plateau and for earlier times including the Medieval Warm Period(MWP).Here we present decadally-resolved,alkenone-based,temperature records from two lakes on the northern Tibetan Plateau.Characterized by marked temperature variability,our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region.Further,our temperature reconstructions,within age uncertainty,can be well correlated with solar irradiance changes,suggesting a possible link between solar forcing and natural climate variability,at least on the northern Tibetan Plateau.展开更多
One of the Holocene abrupt events around 4200 years ago,lasting for~200 years,is thought to have caused cultural disruptions,yet terrestrial climatic status right after the cold/dry event remains poorly defined and is...One of the Holocene abrupt events around 4200 years ago,lasting for~200 years,is thought to have caused cultural disruptions,yet terrestrial climatic status right after the cold/dry event remains poorly defined and is often presumed that a generally cool condition prevailed during the Bronze Age(~4000-2200 years ago).Here we report an alkenone-based summer temperature record over the past~12,000 years,in addition to two updated alkenone records,from Northwest China,providing new insights into the climatic status right after the event.Our results indicate that exceptional terrestrial warmth,up to~6°C,occurred around 4200-2800 years ago during the Bronze Age,superimposed on the long-term Holocene cooling trend.The exceptional warmth in Northwest China,together with other climate anomalies elsewhere,suggests an unusual large-scale climatic reorganization at 4200-2800 years ago when solar activity remained high,with important implications to the climate background for cultural developments during the Bronze Age.展开更多
The northern South China Sea(NSCS)is significantly influenced by the Kuroshio intrusion and the coastal currents.Our knowledge on the roles of both currents on phytoplankton spatial variations is still inadequate.Here...The northern South China Sea(NSCS)is significantly influenced by the Kuroshio intrusion and the coastal currents.Our knowledge on the roles of both currents on phytoplankton spatial variations is still inadequate.Here,we investigated the concentrations of phytoplankton biomarkers and their proportions in surface suspended particles from 47 sites of the NSCS during summer of 2017 and 2019.Brassicasterol/epi-brassicasterol,dinosterol,and C37 alkenones were used as proxies of biomass for diatoms,dinoflagellates,and haptophytes,respectively,and their sum indicating total phytoplankton biomass.A three end-member mixing model was applied to quantitatively assess the influence extent of the Kuroshio intrusion and the coastal currents.Our results showed that the Kuroshio intrusion and the coastal currents contributed equally to the overall surface water masses in the study area;however,the two currents had distinct effects on the spatial distribution of phytoplankton.For phytoplankton biomass,the eutrophic coastal currents were likely to be the main controlling factors,while the impact of the Kuroshio intrusion was weak and stimulated significant increases in phytoplankton biomass only at certain boundary sites.For phytoplankton community structures,the Kuroshio and its intrusion were the main factors,resulting in an increase in the proportions of dinoflagellates and haptophytes.The proportion of diatoms slightly increased due to the influence of the coastal currents.Our study quantifies the effects of the Kuroshio and the coastal currents on phytoplankton in the NSCS in terms of hydrological parameters,providing an important basis for the understanding of ecological functions and biogeochemical cycles in marginal sea-open ocean boundary regions.展开更多
基金supported by the National Basic Research Program of China(2010CB833406, 2010CB428902)Hong Kong Rearch Grants Council(HKU 703809P)+1 种基金supported by the Special Equipment Grant from the University Grants Committee of the Hong Kong Special Administrative Region,China(SEG_HKU01)the CAS/SAFEA International Partnership Program for Creative Research Teams(KZZD-EW-TZ03)
文摘Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions,in order to further understand the mechanisms of past climate variability.Yet,the global coverage of existing temperature records is still limited,especially for some key regions like the Tibetan Plateau and for earlier times including the Medieval Warm Period(MWP).Here we present decadally-resolved,alkenone-based,temperature records from two lakes on the northern Tibetan Plateau.Characterized by marked temperature variability,our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region.Further,our temperature reconstructions,within age uncertainty,can be well correlated with solar irradiance changes,suggesting a possible link between solar forcing and natural climate variability,at least on the northern Tibetan Plateau.
基金financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB40000000)the National Natural Science Foundation of China(41672349,40802084)Hong Kong Research Grants Council(17325516)。
文摘One of the Holocene abrupt events around 4200 years ago,lasting for~200 years,is thought to have caused cultural disruptions,yet terrestrial climatic status right after the cold/dry event remains poorly defined and is often presumed that a generally cool condition prevailed during the Bronze Age(~4000-2200 years ago).Here we report an alkenone-based summer temperature record over the past~12,000 years,in addition to two updated alkenone records,from Northwest China,providing new insights into the climatic status right after the event.Our results indicate that exceptional terrestrial warmth,up to~6°C,occurred around 4200-2800 years ago during the Bronze Age,superimposed on the long-term Holocene cooling trend.The exceptional warmth in Northwest China,together with other climate anomalies elsewhere,suggests an unusual large-scale climatic reorganization at 4200-2800 years ago when solar activity remained high,with important implications to the climate background for cultural developments during the Bronze Age.
基金The study was supported by the National Natural Science Foundation of China(No.41876118)the Global Climate Changes and Air-Sea Interaction Program(No.GASI-02-PAC-ST-Wwin)This is MCTL(Key Laboratory of Marine Chemistry Theory and Technology)contribution#281.
文摘The northern South China Sea(NSCS)is significantly influenced by the Kuroshio intrusion and the coastal currents.Our knowledge on the roles of both currents on phytoplankton spatial variations is still inadequate.Here,we investigated the concentrations of phytoplankton biomarkers and their proportions in surface suspended particles from 47 sites of the NSCS during summer of 2017 and 2019.Brassicasterol/epi-brassicasterol,dinosterol,and C37 alkenones were used as proxies of biomass for diatoms,dinoflagellates,and haptophytes,respectively,and their sum indicating total phytoplankton biomass.A three end-member mixing model was applied to quantitatively assess the influence extent of the Kuroshio intrusion and the coastal currents.Our results showed that the Kuroshio intrusion and the coastal currents contributed equally to the overall surface water masses in the study area;however,the two currents had distinct effects on the spatial distribution of phytoplankton.For phytoplankton biomass,the eutrophic coastal currents were likely to be the main controlling factors,while the impact of the Kuroshio intrusion was weak and stimulated significant increases in phytoplankton biomass only at certain boundary sites.For phytoplankton community structures,the Kuroshio and its intrusion were the main factors,resulting in an increase in the proportions of dinoflagellates and haptophytes.The proportion of diatoms slightly increased due to the influence of the coastal currents.Our study quantifies the effects of the Kuroshio and the coastal currents on phytoplankton in the NSCS in terms of hydrological parameters,providing an important basis for the understanding of ecological functions and biogeochemical cycles in marginal sea-open ocean boundary regions.
