Pub Date : 2025-01-18DOI: 10.1016/j.gloplacha.2025.104704
Guohong Qin, Zixiao Guo, Qingying Du, Yadong Liu, Lanping Feng, Xi Chen, Shahab Varkouhi, Daiyong Cao, Xiaotong Peng
To further constrain the contribution of marine siliceous sediments in the subduction zones to the oceanic gallium (Ga) cycle, we investigated Ga geochemical behavior by examining the mineral, elemental and Ga isotopic compositions of siliceous sediments from the southern Mariana Trench (SMT). The results show that Ga contents vary from 15.6 to 17.6 μg/g (average = 16.7 μg/g) in the lower part of the sediment core but the lower Ga contents (2.7 to 10.9 μg/g, average = 5.9 μg/g) in the upper part. The systematic variation in geochemistry and mineralogical compositions indicates that abundant Ga in the lower part originates from volcanogenic/basaltic rocks, while the addition of biogenic SiO2 to the upper part dilutes the concentration of these source-rock components, resulting in the concomitant decreases in contents of Ga and other elements. Particularly, reverse weathering leads to an increase of Ga in the top section of the upper part by favoring an uptake of Ga in the seawater into aluminosilicates, as evidenced by the range of pH, Al/Nb, Ga/Nb, and Ga/Al variations. In contrast, δ71Ga values (relative to the Ga-IPGP standard) show a monotonous range from −0.06 to 0.05 ‰ (average = −0.01 ‰, n = 17), which is consistent with those for basalts (0.00 ± 0.05 ‰). We find that the addition of biogenic SiO2 and reverse weathering do not significantly change the Ga isotopic compositions in the SMT marine siliceous sediments. Collectively, our study highlights that marine siliceous sediments in the SMT may act as an isotopically light sink of Ga in the modern ocean via reverse weathering, and could shed new light for understanding the oceanic Ga cycles.
{"title":"Gallium behavior and isotopic compositions in marine siliceous sediments from the southern Mariana Trench","authors":"Guohong Qin, Zixiao Guo, Qingying Du, Yadong Liu, Lanping Feng, Xi Chen, Shahab Varkouhi, Daiyong Cao, Xiaotong Peng","doi":"10.1016/j.gloplacha.2025.104704","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104704","url":null,"abstract":"To further constrain the contribution of marine siliceous sediments in the subduction zones to the oceanic gallium (Ga) cycle, we investigated Ga geochemical behavior by examining the mineral, elemental and Ga isotopic compositions of siliceous sediments from the southern Mariana Trench (SMT). The results show that Ga contents vary from 15.6 to 17.6 μg/g (average = 16.7 μg/g) in the lower part of the sediment core but the lower Ga contents (2.7 to 10.9 μg/g, average = 5.9 μg/g) in the upper part. The systematic variation in geochemistry and mineralogical compositions indicates that abundant Ga in the lower part originates from volcanogenic/basaltic rocks, while the addition of biogenic SiO<ce:inf loc=\"post\">2</ce:inf> to the upper part dilutes the concentration of these source-rock components, resulting in the concomitant decreases in contents of Ga and other elements. Particularly, reverse weathering leads to an increase of Ga in the top section of the upper part by favoring an uptake of Ga in the seawater into aluminosilicates, as evidenced by the range of pH, Al/Nb, Ga/Nb, and Ga/Al variations. In contrast, δ<ce:sup loc=\"post\">71</ce:sup>Ga values (relative to the Ga-IPGP standard) show a monotonous range from −0.06 to 0.05 ‰ (average = −0.01 ‰, <ce:italic>n</ce:italic> = 17), which is consistent with those for basalts (0.00 ± 0.05 ‰). We find that the addition of biogenic SiO<ce:inf loc=\"post\">2</ce:inf> and reverse weathering do not significantly change the Ga isotopic compositions in the SMT marine siliceous sediments. Collectively, our study highlights that marine siliceous sediments in the SMT may act as an isotopically light sink of Ga in the modern ocean via reverse weathering, and could shed new light for understanding the oceanic Ga cycles.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"12 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1016/j.gloplacha.2025.104705
Li Xiao, Xiaoyu Zhang, Jinqi Dai, Xueming Li, Ning Zhao, Shihao Liu, Jing Chen, Maotian Li, Yuanhao Sun, Haoyan Wang, Kai Li, Yan Liu, Qianli Sun
Climate fluctuations and human activities shaped vegetation dynamics during the Holocene, yet the underlying mechanisms remain elusive. Our investigation utilizes the MAT-REVEALS approach to analyze 17 fossil pollen records spanning the past 8500 years collected at three typical areas of the lower Yangtze: South Zhejiang Mountains (SZJM), Taihu Basin (THB), and Yaojiang Valley (YJV). The reconstructed vegetation in SZJM revealed a high proportion of arboreal content during 8500–2000 cal yr BP, and the vegetation succession generally followed the variation of mean annual temperature and precipitation, indicating the Asian monsoon climate dominated the vegetation change. Of note, the minor decline of the broadleaved forest at 6000–5000 cal yr BP coincided with the drop in winter temperature, indicating its role as a limiting factor for the broadleaved arboreal. A marked increase of herbs (15.6 % to 36.5 %) occurred in the coastal region of YJV at 7500–5000 cal yr BP, which was not registered in SZJM, was coeval with a surging population and the start of extensive and intensive rice farming on the newly formed alluvial plain, indicating this noticeable landscape openness was induced by anthropogenic factors. Conversely, significant anthropogenic modifications of vegetation only emerged after 5000 cal yr BP in the THB, likely linked to large immigrations of population and the establishment of the Liangzhu hierarchical state that consumed abundant arboreal resources for large-scale constructions. Since 3000–2000 cal yr BP, a widespread decline of arboreal proportion took place in all three areas, which was coeval with a sharp decline of winter temperature as well as the introduction of bronze and later iron to this region during the Spring and Autumn to Three Kingdoms period. Notably, the decline in forest cover in the SZJM region was relatively late. However, it accelerated in the recent millennium, matching the timing of new immigrants from northern China during the Tang-Song dynasties. Overall, natural vegetation changes mainly followed the pattern of monsoon rainfall and winter temperature variations. Nevertheless, the heterogeneity pattern of vegetation changes on the coast underscored the pivotal role of the spatial-temporal distribution of population and advancing technology. This study highlights the regional and local impact of climatic and anthropogenic forces on vegetation composition, providing new insights for interpreting the timing and scale of human impact on past land cover and land use changes.
在全新世期间，气候波动和人类活动塑造了植被动态，但潜在的机制仍然难以捉摸。本研究利用mat -揭示方法分析了在浙南、太湖盆地和姚江流域3个长江下游典型地区采集的17份8500年花粉化石记录。8500 ~ 2000 cal yr BP期间，长江三角洲植被的乔木含量占比较高，植被演替总体上服从年平均气温和降水的变化，表明亚洲季风气候主导了植被的变化。值得注意的是，在6000 ~ 5000 cal yr BP，阔叶林的轻微下降与冬季气温的下降相吻合，表明冬季气温对阔叶林的限制作用。7500 ~ 5000 cal yr BP期间，长江流域沿海地区草本植物显著增加（15.6% ~ 36.5%），而长江流域未记录到这一变化，这与人口激增和新形成的冲积平原开始广泛集约种植水稻同时发生，表明这种明显的景观开放是由人为因素引起的。相反，人类对THB地区植被的显著改变仅在5000 cal yr BP之后才出现，这可能与人口的大规模移民和良渚等级国家的建立有关，这些国家消耗了大量的树木资源进行大规模建设。自3000-2000 cal yr BP以来，这三个地区树木比例普遍下降，与冬季气温急剧下降以及春秋三国时期青铜和后来的铁传入该地区同时发生。值得注意的是，SZJM地区森林覆盖下降的时间相对较晚。然而，在最近的千年里，它加速了，与唐宋时期来自中国北方的新移民的时间相匹配。总体而言，自然植被变化主要遵循季风降水和冬季气温变化的格局。然而，沿海植被变化的异质性格局强调了人口时空分布和技术进步的关键作用。该研究强调了气候和人为力量对植被组成的区域和局部影响，为解释人类对过去土地覆盖和土地利用变化的影响时间和规模提供了新的见解。
{"title":"Population migration with improved productivity caused a heterogeneity pattern of Holocene vegetation succession in typical areas of the lower Yangtze region","authors":"Li Xiao, Xiaoyu Zhang, Jinqi Dai, Xueming Li, Ning Zhao, Shihao Liu, Jing Chen, Maotian Li, Yuanhao Sun, Haoyan Wang, Kai Li, Yan Liu, Qianli Sun","doi":"10.1016/j.gloplacha.2025.104705","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104705","url":null,"abstract":"Climate fluctuations and human activities shaped vegetation dynamics during the Holocene, yet the underlying mechanisms remain elusive. Our investigation utilizes the MAT-REVEALS approach to analyze 17 fossil pollen records spanning the past 8500 years collected at three typical areas of the lower Yangtze: South Zhejiang Mountains (SZJM), Taihu Basin (THB), and Yaojiang Valley (YJV). The reconstructed vegetation in SZJM revealed a high proportion of arboreal content during 8500–2000 cal yr BP, and the vegetation succession generally followed the variation of mean annual temperature and precipitation, indicating the Asian monsoon climate dominated the vegetation change. Of note, the minor decline of the broadleaved forest at 6000–5000 cal yr BP coincided with the drop in winter temperature, indicating its role as a limiting factor for the broadleaved arboreal. A marked increase of herbs (15.6 % to 36.5 %) occurred in the coastal region of YJV at 7500–5000 cal yr BP, which was not registered in SZJM, was coeval with a surging population and the start of extensive and intensive rice farming on the newly formed alluvial plain, indicating this noticeable landscape openness was induced by anthropogenic factors. Conversely, significant anthropogenic modifications of vegetation only emerged after 5000 cal yr BP in the THB, likely linked to large immigrations of population and the establishment of the Liangzhu hierarchical state that consumed abundant arboreal resources for large-scale constructions. Since 3000–2000 cal yr BP, a widespread decline of arboreal proportion took place in all three areas, which was coeval with a sharp decline of winter temperature as well as the introduction of bronze and later iron to this region during the Spring and Autumn to Three Kingdoms period. Notably, the decline in forest cover in the SZJM region was relatively late. However, it accelerated in the recent millennium, matching the timing of new immigrants from northern China during the Tang-Song dynasties. Overall, natural vegetation changes mainly followed the pattern of monsoon rainfall and winter temperature variations. Nevertheless, the heterogeneity pattern of vegetation changes on the coast underscored the pivotal role of the spatial-temporal distribution of population and advancing technology. This study highlights the regional and local impact of climatic and anthropogenic forces on vegetation composition, providing new insights for interpreting the timing and scale of human impact on past land cover and land use changes.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"38 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.gloplacha.2025.104702
Danielle C. Verdon-Kidd, Kathryn J. Allen, Luke J. Kidd, Carolyn Maxwell, Mark Willis, Patrick Baker
Robust hydroclimate risk assessment requires a thorough understanding of past climate variability, which can be achieved by supplementing short instrumental hydroclimate records with palaeoclimate data. However, long-term continuous simulation of catchments and storage modelling, essential for hydrological risk assessment, necessitates monthly or daily time series input data, while palaeoclimate records are typically available at annual or seasonal scales. Additionally, modelling operational water storages used for hydropower is complex, requiring inputs such as water extraction information, which are difficult to replicate due to their inherent variability. Based on Lake Burbury, part of Hydro Tasmania's hydroelectric scheme in southern Australia, we demonstrate a novel method through which seasonal flow reconstructions can be used for daily palaeo water balance modelling, coupled with an Artificial Neural Network (ANN) model to simulate storage extractions. We first developed two seasonal tree-ring based inflow reconstructions, an approximately 1000-year Austral summer and a 400-year Austral winter reconstruction. We then used these as a guide to bootstrap historical daily inflows and the ANN known as Long Short-Term Memory (LSTM) was trained to simulate extractions for hydroelectricity. A Source model of the Lake Burbury hydro-electric water supply system was prepared to simulate the daily surface water balance of Lake Burbury, including inflows, outflows and resultant storage levels over some 1000 years. The simulations were used to ‘stress test’ the current storage system under a broader range of climatic conditions than the instrumental period. Based on our simulation, a low flow period like that in the 18th century represents the highest risk to hydroelectricity production, while a repeat of 12-13th century conditions would be associated with the highest spill volumes and most reliable electricity production. Importantly, by extending the instrumental record, we can place contemporary trends in water availability in a longer historical context, better assess the likelihood of extreme events, and hence adjust plans to decrease the vulnerability of the hydroelectric sector (among other water users) to drought/shifts in climate. This approach requires collaboration between palaeoclimatologists, the modelling community, hydrologists and managers of natural resources and the built environment.
{"title":"Using seasonal palaeo-flow reconstructions and artificial neural networks for daily water balance modelling: A case study from Tasmania, Australia","authors":"Danielle C. Verdon-Kidd, Kathryn J. Allen, Luke J. Kidd, Carolyn Maxwell, Mark Willis, Patrick Baker","doi":"10.1016/j.gloplacha.2025.104702","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104702","url":null,"abstract":"Robust hydroclimate risk assessment requires a thorough understanding of past climate variability, which can be achieved by supplementing short instrumental hydroclimate records with palaeoclimate data. However, long-term continuous simulation of catchments and storage modelling, essential for hydrological risk assessment, necessitates monthly or daily time series input data, while palaeoclimate records are typically available at annual or seasonal scales. Additionally, modelling operational water storages used for hydropower is complex, requiring inputs such as water extraction information, which are difficult to replicate due to their inherent variability. Based on Lake Burbury, part of Hydro Tasmania's hydroelectric scheme in southern Australia, we demonstrate a novel method through which seasonal flow reconstructions can be used for daily palaeo water balance modelling, coupled with an Artificial Neural Network (ANN) model to simulate storage extractions. We first developed two seasonal tree-ring based inflow reconstructions, an approximately 1000-year Austral summer and a 400-year Austral winter reconstruction. We then used these as a guide to bootstrap historical daily inflows and the ANN known as Long Short-Term Memory (LSTM) was trained to simulate extractions for hydroelectricity. A Source model of the Lake Burbury hydro-electric water supply system was prepared to simulate the daily surface water balance of Lake Burbury, including inflows, outflows and resultant storage levels over some 1000 years. The simulations were used to ‘stress test’ the current storage system under a broader range of climatic conditions than the instrumental period. Based on our simulation, a low flow period like that in the 18th century represents the highest risk to hydroelectricity production, while a repeat of 12-13th century conditions would be associated with the highest spill volumes and most reliable electricity production. Importantly, by extending the instrumental record, we can place contemporary trends in water availability in a longer historical context, better assess the likelihood of extreme events, and hence adjust plans to decrease the vulnerability of the hydroelectric sector (among other water users) to drought/shifts in climate. This approach requires collaboration between palaeoclimatologists, the modelling community, hydrologists and managers of natural resources and the built environment.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"32 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.gloplacha.2025.104706
Babak Ghazi, Rajmund Przybylak, Piotr Oliński, Aleksandra Pospieszyńska
In the current era of global climate change, extreme events such as flood exposure are increasing globally. Knowledge about floods during historical periods is limited worldwide, mainly due to gaps in the documentary evidence and the lack of a reliable, comprehensive database. A new comprehensive database of floods in Poland in the 11th–18th centuries was created using quality-controlled documentary evidence. In addition, a list of floods for the 19th and 20th centuries was created based on a literature review. Using all these data, the frequency, intensity, genesis, and spatial distribution of floods in Poland in the last millennium were investigated. Results revealed the occurrence of 1680 floods in Poland in the last millennium. The 18th century was the most abundant in recorded floods (356, 21 %). Floods in the period 1001–1800 were most frequent in the Silesia region (553, 43 %) and in the Oder River basin (671, 55 %). The number of floods was greatest in summer (JJA, 46 %) and the lowest in autumn (SON, 8 %). An investigation of the origin of floods indicated that rain was the main contributing factor to the occurrences of floods in Poland (44 %). The estimation of the intensity of floods showed that most of them were of extreme nature: “above-average, or supra-regional flood” (33 %) and “extraordinary” floods (70 %). Analysis of the multi-temporal trend demonstrated that, overall, for the periods of 1501–1700 and 1601–1800, positive trends were more numerous than negative trends, whereas, for 1801–2000, negative trends were slightly more numerous than positive trends.
{"title":"Flood occurrences and characteristics in Poland (Central Europe) in the last millennium","authors":"Babak Ghazi, Rajmund Przybylak, Piotr Oliński, Aleksandra Pospieszyńska","doi":"10.1016/j.gloplacha.2025.104706","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104706","url":null,"abstract":"In the current era of global climate change, extreme events such as flood exposure are increasing globally. Knowledge about floods during historical periods is limited worldwide, mainly due to gaps in the documentary evidence and the lack of a reliable, comprehensive database. A new comprehensive database of floods in Poland in the 11th–18th centuries was created using quality-controlled documentary evidence. In addition, a list of floods for the 19th and 20th centuries was created based on a literature review. Using all these data, the frequency, intensity, genesis, and spatial distribution of floods in Poland in the last millennium were investigated. Results revealed the occurrence of 1680 floods in Poland in the last millennium. The 18th century was the most abundant in recorded floods (356, 21 %). Floods in the period 1001–1800 were most frequent in the Silesia region (553, 43 %) and in the Oder River basin (671, 55 %). The number of floods was greatest in summer (JJA, 46 %) and the lowest in autumn (SON, 8 %). An investigation of the origin of floods indicated that rain was the main contributing factor to the occurrences of floods in Poland (44 %). The estimation of the intensity of floods showed that most of them were of extreme nature: “above-average, or supra-regional flood” (33 %) and “extraordinary” floods (70 %). Analysis of the multi-temporal trend demonstrated that, overall, for the periods of 1501–1700 and 1601–1800, positive trends were more numerous than negative trends, whereas, for 1801–2000, negative trends were slightly more numerous than positive trends.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"74 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.gloplacha.2025.104701
Lina Song, Dongmei Jie, Feng Xie, Guizai Gao, Xianyong Cao
Understanding long-term regional anthropogenic impacts on vegetation can enhance our knowledge of natural environmental development. In this study, a 140-cm-long peat core covering the last ∼2850 years collected from the Changbai Mountain range was analysed for pollen and charcoal, to reconstruct vegetation and fire history, and to investigate the intensity and effects of human activities. Results show that the forest gradually shrank as precipitation decreased before around 1000 cal yr BP, characterised by the relative changes between Pinus and broad-leaved taxa. Over the last millennium, the forest further shrank, with broad-leaved components relatively increasing and herbaceous species significantly expanding at the cost of Pinus. Human activities in the Changbai Mountains have intensified since 1500 cal yr BP, as inferred from the increase in anthropogenic pollen indicators, along with a rise in both the frequency and intensity of palaeofire. Notably, human activities via the selective felling of Pinus and facilitation of the expansion of herbaceous species have disturbed the vegetation-climate relationship and thus introduced a bias into pollen-based climate reconstructions covering the last millennium. Additionally, human activities increased the frequency and intensity of palaeofire, with a significant contribution of local fires. We highlight that in the context of enhanced anthropogenic impact on the natural vegetation, pollen-based palaeoclimate reconstructions should be approached carefully.
{"title":"Enhanced human activities have disturbed the vegetation-climate relationship over the last millennium in the Changbai Mountains, north-east China","authors":"Lina Song, Dongmei Jie, Feng Xie, Guizai Gao, Xianyong Cao","doi":"10.1016/j.gloplacha.2025.104701","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104701","url":null,"abstract":"Understanding long-term regional anthropogenic impacts on vegetation can enhance our knowledge of natural environmental development. In this study, a 140-cm-long peat core covering the last ∼2850 years collected from the Changbai Mountain range was analysed for pollen and charcoal, to reconstruct vegetation and fire history, and to investigate the intensity and effects of human activities. Results show that the forest gradually shrank as precipitation decreased before around 1000 cal yr BP, characterised by the relative changes between <ce:italic>Pinus</ce:italic> and broad-leaved taxa. Over the last millennium, the forest further shrank, with broad-leaved components relatively increasing and herbaceous species significantly expanding at the cost of <ce:italic>Pinus</ce:italic>. Human activities in the Changbai Mountains have intensified since 1500 cal yr BP, as inferred from the increase in anthropogenic pollen indicators, along with a rise in both the frequency and intensity of palaeofire. Notably, human activities via the selective felling of <ce:italic>Pinus</ce:italic> and facilitation of the expansion of herbaceous species have disturbed the vegetation-climate relationship and thus introduced a bias into pollen-based climate reconstructions covering the last millennium. Additionally, human activities increased the frequency and intensity of palaeofire, with a significant contribution of local fires. We highlight that in the context of enhanced anthropogenic impact on the natural vegetation, pollen-based palaeoclimate reconstructions should be approached carefully.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"32 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1016/j.gloplacha.2025.104698
Alberto Sáez, Armand Hernández, Adriano Pimentel, Mariana Andrade, Roberto Bao, Pedro M. Raposeiro, Vitor Gonçalves, Mario Benavente, Sergi Pla-Rabes, Ricardo Ramalho, Santiago Giralt
The Azores region plays a crucial role as a pathway for precipitation fronts traversing the North Atlantic from west to east, driven by the prevailing westerly winds. Variations in the strength of the Azores High affect the dynamics of the North Atlantic Oscillation (NAO), leading to latitudinal shifts in the trajectory of the westerlies and jet stream current over time.
{"title":"Westerlies migrations and volcanic records over the past 4000 years from the Azores lacustrine sequences. Exploring correlations and impacts on Western Europe","authors":"Alberto Sáez, Armand Hernández, Adriano Pimentel, Mariana Andrade, Roberto Bao, Pedro M. Raposeiro, Vitor Gonçalves, Mario Benavente, Sergi Pla-Rabes, Ricardo Ramalho, Santiago Giralt","doi":"10.1016/j.gloplacha.2025.104698","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104698","url":null,"abstract":"The Azores region plays a crucial role as a pathway for precipitation fronts traversing the North Atlantic from west to east, driven by the prevailing westerly winds. Variations in the strength of the Azores High affect the dynamics of the North Atlantic Oscillation (NAO), leading to latitudinal shifts in the trajectory of the westerlies and jet stream current over time.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"206 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-07DOI: 10.1016/j.gloplacha.2025.104699
Feng Wang, Tuqin Huang, Zhongbo Wang, Weiguo Zhang, Pengyu Qiao, Haiyan Tang, Xi Mei, Ping Yin, Zhongping Lai
The Kuroshio Current significantly influences the physical, chemical, and biological properties in the western Pacific Ocean, while its strength and path in the Okinawa Trough during the Holocene remains unclear. Previous studies have not established consistent conclusions due to the multiple explanations for sediment provenance proxies, but these inconsistencies can potentially be addressed by identifying redox variability through diagenetic effects on magnetic minerals. Magnetic data (χ, SIRM, χARM, and S-ratios) obtained from cores SHDZ10 and A4 in the middle Okinawa Trough indicate an intensified reductive diagenesis effect prior to the early-middle Holocene period, whereas a contrasting trend is observed since the early-middle Holocene. Geochemical analyses (Mo, Mn, Mo/Mn, Mn/Al, TOC and TS) and Pulleniatina obliquiloculata content variations suggest that the decrease in early diagenesis since early-middle Holocene was a consequence of increased oxygenation, which is related to a strengthened Kuroshio Current and enhanced deep-water ventilation. By synthesizing the observed redox transition phenomena in nearby sediment cores (MD012403, MD012404, KX12–3, MD063–05, CSH1), we discover a coherent redox transition event during the early-middle Holocene. The occurrence ages show millennial-scale variability from south to north, which may suggest a periodic northward movement trajectory of a strengthened Kuroshio Current. This study not only provides novel insights into the reconstruction of the Kuroshio Current evolution, but also highlights the applicability of environmental magnetism methods in investigating deep-water ventilation.
{"title":"Magnetic evidence of redox transition event in the Okinawa Trough during the early-middle Holocene and its links to the Kuroshio Current evolution","authors":"Feng Wang, Tuqin Huang, Zhongbo Wang, Weiguo Zhang, Pengyu Qiao, Haiyan Tang, Xi Mei, Ping Yin, Zhongping Lai","doi":"10.1016/j.gloplacha.2025.104699","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104699","url":null,"abstract":"The Kuroshio Current significantly influences the physical, chemical, and biological properties in the western Pacific Ocean, while its strength and path in the Okinawa Trough during the Holocene remains unclear. Previous studies have not established consistent conclusions due to the multiple explanations for sediment provenance proxies, but these inconsistencies can potentially be addressed by identifying redox variability through diagenetic effects on magnetic minerals. Magnetic data (χ, SIRM, χ<ce:inf loc=\"post\">ARM</ce:inf>, and S-ratios) obtained from cores SHDZ10 and A4 in the middle Okinawa Trough indicate an intensified reductive diagenesis effect prior to the early-middle Holocene period, whereas a contrasting trend is observed since the early-middle Holocene. Geochemical analyses (Mo, Mn, Mo/Mn, Mn/Al, TOC and TS) and <ce:italic>Pulleniatina obliquiloculata</ce:italic> content variations suggest that the decrease in early diagenesis since early-middle Holocene was a consequence of increased oxygenation, which is related to a strengthened Kuroshio Current and enhanced deep-water ventilation. By synthesizing the observed redox transition phenomena in nearby sediment cores (MD012403, MD012404, KX12–3, MD063–05, CSH1), we discover a coherent redox transition event during the early-middle Holocene. The occurrence ages show millennial-scale variability from south to north, which may suggest a periodic northward movement trajectory of a strengthened Kuroshio Current. This study not only provides novel insights into the reconstruction of the Kuroshio Current evolution, but also highlights the applicability of environmental magnetism methods in investigating deep-water ventilation.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"22 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
BrGMGTs (branched glycerol monoalkyl glycerol tetraethers) are proposed as potential proxies for temperature estimation due to their constrained and consistent biological origin. However, discrepancies observed between brGMGTs-based proxies and MAAT (mean annual air temperature) have raised concerns about their applicability. Here, we analyzed surface samples from three peatlands across China, and two well-dated Holocene peat cores. We found: 1) surface peat samples showed that %brGMGTs (abundance of brGMGTs relative to brGMGTs and brGDGTs; brGDGTs: branched glycerol dialkyl glycerol tetraethers) and H-MBT (methylation degree of brGMGTs) were ineffective to represent temperature. 2) Holocene records of %brGMGTs and H-MBT were uncorrelated with MBT’5ME records (previously established as reliable temperature records) in the same cores, as well as with regional other proxy temperature records. Our data, along with the global peat dataset, indicated that brGMGTs are ineffective for temperature estimation under cold conditions (MAAT <10 °C). This ineffectiveness may be due to unfavorable temperature niches, changes in aerobic/anaerobic conditions and microbial communities. By setting a threshold (%brGMGTs >4 %), we found that H-MBT showed a higher positive correlation with MAAT (R2 = 0.50, p < 0.01, n = 26), compared to all samples (R2 = 0.47, p < 0.01, n = 72). Although this improvement in correlation is modest, it helps exclude samples with MAAT <10 °C. Our revised method for temperature estimation using brGMGTs could potentially be applied to peat sediments with MAAT ranging from 10 °C to 27 °C, enhancing their application for paleotemperature reconstruction in future research.
BrGMGTs（支链甘油单烷基甘油四醚）由于其受约束和一致的生物来源而被提出作为温度估计的潜在代理。然而，基于brgmgts的代用物与MAAT（年平均气温）之间观测到的差异引起了人们对其适用性的担忧。在这里，我们分析了来自中国三个泥炭地的地表样本，以及两个年代确定的全新世泥炭岩心。结果表明：1)表层泥炭样品中brGMGTs（相对于brGMGTs和brGMGTs的丰度）%；brGMGTs：支化甘油二烷基甘油四醚)和H-MBT （brGMGTs的甲基化程度）不能代表温度。2)全新世的% brgmgt和H-MBT记录与同一岩心的MBT’5ME记录（以前建立的可靠温度记录）以及区域其他代理温度记录不相关。我们的数据以及全球泥炭数据表明，在寒冷条件下（MAAT <10°C）， brGMGTs对温度估计无效。这种无效可能是由于不利的温度生态位，好氧/厌氧条件和微生物群落的变化。通过设置阈值（%brGMGTs > 4%），我们发现H-MBT与MAAT有较高的正相关(R2 = 0.50, p <；0.01, n = 26)，与所有样本相比(R2 = 0.47, p <；0.01, n = 72)。虽然这种相关性的改善是适度的，但它有助于排除MAAT <；10°C的样品。修正后的brGMGTs温度估算方法可应用于MAAT范围为10 ~ 27℃的泥炭沉积物，增强了其在未来研究中古温度重建的应用价值。
{"title":"Testing and improving brGMGTs-based paleotemperature estimates in peat sediments: Evidence from global surface peat samples and two well-dated Holocene peat cores in far Northwest China","authors":"Zhongwei Shen, Minghua Zhao, Tianyan Lin, Xiaoxu Qu, Haichun Guo, Jiantao Cao, Guodong Jia, Zhiguo Rao","doi":"10.1016/j.gloplacha.2025.104700","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104700","url":null,"abstract":"BrGMGTs (branched glycerol monoalkyl glycerol tetraethers) are proposed as potential proxies for temperature estimation due to their constrained and consistent biological origin. However, discrepancies observed between brGMGTs-based proxies and MAAT (mean annual air temperature) have raised concerns about their applicability. Here, we analyzed surface samples from three peatlands across China, and two well-dated Holocene peat cores. We found: 1) surface peat samples showed that %brGMGTs (abundance of brGMGTs relative to brGMGTs and brGDGTs; brGDGTs: branched glycerol dialkyl glycerol tetraethers) and H-MBT (methylation degree of brGMGTs) were ineffective to represent temperature. 2) Holocene records of %brGMGTs and H-MBT were uncorrelated with MBT’<ce:inf loc=\"post\">5ME</ce:inf> records (previously established as reliable temperature records) in the same cores, as well as with regional other proxy temperature records. Our data, along with the global peat dataset, indicated that brGMGTs are ineffective for temperature estimation under cold conditions (MAAT <10 °C). This ineffectiveness may be due to unfavorable temperature niches, changes in aerobic/anaerobic conditions and microbial communities. By setting a threshold (%brGMGTs >4 %), we found that H-MBT showed a higher positive correlation with MAAT (<ce:italic>R</ce:italic><ce:sup loc=\"post\"><ce:italic>2</ce:italic></ce:sup> = 0.50, <ce:italic>p</ce:italic> < 0.01, <ce:italic>n</ce:italic> = 26), compared to all samples (<ce:italic>R</ce:italic><ce:sup loc=\"post\"><ce:italic>2</ce:italic></ce:sup> = 0.47, <ce:italic>p</ce:italic> < 0.01, <ce:italic>n</ce:italic> = 72). Although this improvement in correlation is modest, it helps exclude samples with MAAT <10 °C. Our revised method for temperature estimation using brGMGTs could potentially be applied to peat sediments with MAAT ranging from 10 °C to 27 °C, enhancing their application for paleotemperature reconstruction in future research.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"74 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Methane (CH4) ranks as the second most significant anthropogenic greenhouse gas following carbon dioxide (CO2). It originates from a wide range of surface sources and subsequently enters the stratosphere through the tropical tropopause. In line with the observed positive trend in tropospheric CH4, stratospheric CH4 has shown an overall increase in the long-term trend. However, contrary to the continuous increase in tropospheric CH4, stratospheric CH4 exhibits a temporal decrease in the Northern Hemisphere middle and upper stratosphere during short-time periods. This study investigates the causes behind the decreasing trend of stratospheric CH4 in the Northern Hemisphere from 1991 to 2000. We find that the extreme decrease of stratospheric CH4 from July 1994 to May 1997 contributes to the overall decreasing trend of CH4 from 1991 to 2000. This extreme decrease is attributed to the weakened meridional component of the residual circulation. The weakened meridional component attenuates the transport of CH4-rich air from the low-latitude lower stratosphere to the mid-latitude middle and upper stratosphere, leading to the observed decrease in CH4. It is further found that the smallest SST gradient in the North Pacific and adjacent regions from 1980 to 2020 is identified as a significant factor contributing to the weakened residual circulation and the decrease in CH4. Simulations by a chemistry-climate model support the results.
{"title":"Impact of the 1994–1997 temporary decrease in Northern Hemisphere stratospheric methane on the 1990s methane trend","authors":"Yuanyuan Han, Shentao Li, Xinlong Tan, Wenyan Guo, Wuhu Feng, Xin Li, Feiyang Wang, Fei Xie","doi":"10.1016/j.gloplacha.2025.104697","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104697","url":null,"abstract":"Methane (CH<ce:inf loc=\"post\">4</ce:inf>) ranks as the second most significant anthropogenic greenhouse gas following carbon dioxide (CO<ce:inf loc=\"post\">2</ce:inf>). It originates from a wide range of surface sources and subsequently enters the stratosphere through the tropical tropopause. In line with the observed positive trend in tropospheric CH<ce:inf loc=\"post\">4</ce:inf>, stratospheric CH<ce:inf loc=\"post\">4</ce:inf> has shown an overall increase in the long-term trend. However, contrary to the continuous increase in tropospheric CH<ce:inf loc=\"post\">4</ce:inf>, stratospheric CH<ce:inf loc=\"post\">4</ce:inf> exhibits a temporal decrease in the Northern Hemisphere middle and upper stratosphere during short-time periods. This study investigates the causes behind the decreasing trend of stratospheric CH<ce:inf loc=\"post\">4</ce:inf> in the Northern Hemisphere from 1991 to 2000. We find that the extreme decrease of stratospheric CH<ce:inf loc=\"post\">4</ce:inf> from July 1994 to May 1997 contributes to the overall decreasing trend of CH<ce:inf loc=\"post\">4</ce:inf> from 1991 to 2000. This extreme decrease is attributed to the weakened meridional component of the residual circulation. The weakened meridional component attenuates the transport of CH<ce:inf loc=\"post\">4</ce:inf>-rich air from the low-latitude lower stratosphere to the mid-latitude middle and upper stratosphere, leading to the observed decrease in CH<ce:inf loc=\"post\">4</ce:inf>. It is further found that the smallest SST gradient in the North Pacific and adjacent regions from 1980 to 2020 is identified as a significant factor contributing to the weakened residual circulation and the decrease in CH<ce:inf loc=\"post\">4</ce:inf>. Simulations by a chemistry-climate model support the results.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"91 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the variability and forcing mechanisms of the East Asian summer monsoon (EASM) precipitation on different timescales is critically important given its potentially adverse influence on ecosystems and economic development in North China. We present a pollen-based, well-dated, ∼10 yr resolution quantitative precipitation reconstruction from an alpine lake in North China, which provides a detailed picture of EASM evolution during the past ∼11,860 years. Based on ensemble empirical mode decomposition (EEMD) method and spectral analysis, we have revealed the centennial to multidecadal scales variability of EASM precipitation and its possible driving mechanisms during the Holocene. Our results suggest that the mean annual precipitation (MAP) varied greatly during the Holocene, with the maximum precipitation (520 mm) occurring during 9500–5020 cal. yr BP, which was ∼20 % higher than present. On the centennial scale, EASM precipitation exhibited ∼500 yr, ∼200 yr, ∼130 yr, and ∼105 yr cycles. The amplitude of the ∼500 yr cycle varied greatly during the Holocene, being higher in the early and late Holocene and lower in the middle Holocene, which was possibly linked to changes in ocean circulation induced by freshwater influx to the North Atlantic. On the multidecadal scale, the EASM precipitation was dominated by a 70–90 yr cycle, which may be related to the solar activity cycle and ocean-atmosphere interactions at both high and low latitudes. Weaker (stronger) solar activity, combined with stronger El Niño-Southern Oscillation (ENSO) during the warm phase of the Pacific Interdecadal Oscillation (PDO) and a negative phase of the Atlantic Multidecadal Oscillation (AMO), caused lower (higher) sea surface temperatures (SSTs) in the Indo-West Pacific Warm Pool (IWPWP) region, resulted in weaker (stronger) EASM circulation and decreased (increased) precipitation in North China. Our findings provide significant enlightenment for distinguishing the contribution of natural factors to the changes in EASM precipitation under future global warming scenarios.
{"title":"Centennial to multidecadal scales variability of East Asian summer monsoon precipitation in North China during the Holocene","authors":"Dandan Wang, Qinghai Xu, Yuanhao Sun, Shengrui Zhang","doi":"10.1016/j.gloplacha.2025.104692","DOIUrl":"https://doi.org/10.1016/j.gloplacha.2025.104692","url":null,"abstract":"Understanding the variability and forcing mechanisms of the East Asian summer monsoon (EASM) precipitation on different timescales is critically important given its potentially adverse influence on ecosystems and economic development in North China. We present a pollen-based, well-dated, ∼10 yr resolution quantitative precipitation reconstruction from an alpine lake in North China, which provides a detailed picture of EASM evolution during the past ∼11,860 years. Based on ensemble empirical mode decomposition (EEMD) method and spectral analysis, we have revealed the centennial to multidecadal scales variability of EASM precipitation and its possible driving mechanisms during the Holocene. Our results suggest that the mean annual precipitation (MAP) varied greatly during the Holocene, with the maximum precipitation (520 mm) occurring during 9500–5020 cal. yr BP, which was ∼20 % higher than present. On the centennial scale, EASM precipitation exhibited ∼500 yr, ∼200 yr, ∼130 yr, and ∼105 yr cycles. The amplitude of the ∼500 yr cycle varied greatly during the Holocene, being higher in the early and late Holocene and lower in the middle Holocene, which was possibly linked to changes in ocean circulation induced by freshwater influx to the North Atlantic. On the multidecadal scale, the EASM precipitation was dominated by a 70–90 yr cycle, which may be related to the solar activity cycle and ocean-atmosphere interactions at both high and low latitudes. Weaker (stronger) solar activity, combined with stronger El Niño-Southern Oscillation (ENSO) during the warm phase of the Pacific Interdecadal Oscillation (PDO) and a negative phase of the Atlantic Multidecadal Oscillation (AMO), caused lower (higher) sea surface temperatures (SSTs) in the Indo-West Pacific Warm Pool (IWPWP) region, resulted in weaker (stronger) EASM circulation and decreased (increased) precipitation in North China. Our findings provide significant enlightenment for distinguishing the contribution of natural factors to the changes in EASM precipitation under future global warming scenarios.","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"28 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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