Pub Date : 2026-02-01Epub Date: 2025-12-06DOI: 10.1016/j.gloplacha.2025.105237
Zitong Wang , Chen Liang , Kai Chen , Xianyong Cao
Understanding long-term interactions between climate, permafrost, and vegetation provides an essential context for interpreting current Arctic greening. Using 65 fossil pollen records from northern Siberia and a Random Forest model trained on a dataset of 835 modern pollen–climate assemblages, we quantitatively reconstructed mean temperature of the warmest month (Mtwa: mean July temperature) anomalies over the past 40 thousand years (ka) and assessed associated vegetation changes. During the Last Glacial Period, herbaceous taxa overwhelmingly dominated, and warming of ∼1 °C during ∼40–35 cal ka BP was insufficient to deepen the active layer beyond the threshold required for tree establishment, leaving woody cover minimal. In the early Holocene, sustained warming of nearly 2 °C triggered permafrost degradation and active-layer thickening, enabling forest expansion, although tree taxa lagged shrubs by several millennia. These results reveal a clear threshold effect in vegetation–permafrost interactions and show that only sustained warming can overcome permafrost constraints. By providing quantitative temperature estimates, our reconstruction offers critical benchmarks for predicting how ongoing Arctic warming may transform vegetation patterns and permafrost stability.
了解气候、永久冻土和植被之间的长期相互作用为解释当前的北极绿化提供了一个重要的背景。利用来自西伯利亚北部的65份花粉化石记录和基于835份现代花粉-气候组合数据集的随机森林模型，我们定量地重建了过去4万年（ka）最温暖月份的平均温度（Mtwa: 7月平均温度）异常，并评估了相关的植被变化。在末次冰期，草本类群占绝对优势，在~ 40-35 cal ka BP期间的~ 1°C升温不足以使活性层加深到超过树木生长所需的阈值，使木质覆盖最小。在全新世早期，近2°C的持续变暖引发了永久冻土退化和活动层增厚，使森林得以扩张，尽管乔木类群落后于灌木几千年。这些结果揭示了植被-永久冻土相互作用中明显的阈值效应，并表明只有持续变暖才能克服永久冻土的限制。通过提供定量的温度估计，我们的重建为预测持续的北极变暖如何改变植被模式和永久冻土稳定性提供了关键的基准。
{"title":"Permafrost dampens long-term vegetation responses to climate change in northern Siberia: Evidence from pollen spectra covering the last 40 kyr","authors":"Zitong Wang , Chen Liang , Kai Chen , Xianyong Cao","doi":"10.1016/j.gloplacha.2025.105237","DOIUrl":"10.1016/j.gloplacha.2025.105237","url":null,"abstract":"<div><div>Understanding long-term interactions between climate, permafrost, and vegetation provides an essential context for interpreting current Arctic greening. Using 65 fossil pollen records from northern Siberia and a Random Forest model trained on a dataset of 835 modern pollen–climate assemblages, we quantitatively reconstructed mean temperature of the warmest month (Mtwa: mean July temperature) anomalies over the past 40 thousand years (ka) and assessed associated vegetation changes. During the Last Glacial Period, herbaceous taxa overwhelmingly dominated, and warming of ∼1 °C during ∼40–35 cal ka BP was insufficient to deepen the active layer beyond the threshold required for tree establishment, leaving woody cover minimal. In the early Holocene, sustained warming of nearly 2 °C triggered permafrost degradation and active-layer thickening, enabling forest expansion, although tree taxa lagged shrubs by several millennia. These results reveal a clear threshold effect in vegetation–permafrost interactions and show that only sustained warming can overcome permafrost constraints. By providing quantitative temperature estimates, our reconstruction offers critical benchmarks for predicting how ongoing Arctic warming may transform vegetation patterns and permafrost stability.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105237"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690062","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}
Intensified water stress driven by greenhouse gas-induced warming plays a pivotal role in regulating terrestrial vegetation growth across arid-to-humid transition zones, with significant implications for the global carbon cycle. However, the shifting sensitivity of the vegetation productivity to a warming climate remains poorly understood. Since the early 2000s, Northeast (NEA) has experienced pronounced reductions in gross primary production (GPP), primarily attributed to notable soil moisture (SM) decreases and water vapor deficit (VPD) increases. Our study explored the relative dominance of SM and VPD to GPP variations through random forest (RF) algorithm, and demonstrated distinct varied responses of vegetation growth across aridity gradients: vegetation growth in arid regions is predominantly influenced by SM, while VPD exerts a stronger influence in semi-arid to humid zones. Under warming and drying conditions, GPP sensitivity to water availability intensified, with vegetation in semi-arid to humid zones becoming increasingly vulnerable to VPD. As drylands expand and climate variability intensifies, understanding these sensitivities is essential for predicting ecosystem vulnerability and assessing vegetation responses to future climate scenarios.
{"title":"Aridification enhancing vegetation sensitivities to soil and atmospheric dryness in Northeast Asia","authors":"Zhikai Wang , Wen Chen , Jinling Piao , Shangfeng Chen , Changhao Wu","doi":"10.1016/j.gloplacha.2025.105244","DOIUrl":"10.1016/j.gloplacha.2025.105244","url":null,"abstract":"<div><div>Intensified water stress driven by greenhouse gas-induced warming plays a pivotal role in regulating terrestrial vegetation growth across arid-to-humid transition zones, with significant implications for the global carbon cycle. However, the shifting sensitivity of the vegetation productivity to a warming climate remains poorly understood. Since the early 2000s, Northeast (NEA) has experienced pronounced reductions in gross primary production (GPP), primarily attributed to notable soil moisture (SM) decreases and water vapor deficit (VPD) increases. Our study explored the relative dominance of SM and VPD to GPP variations through random forest (RF) algorithm, and demonstrated distinct varied responses of vegetation growth across aridity gradients: vegetation growth in arid regions is predominantly influenced by SM, while VPD exerts a stronger influence in semi-arid to humid zones. Under warming and drying conditions, GPP sensitivity to water availability intensified, with vegetation in semi-arid to humid zones becoming increasingly vulnerable to VPD. As drylands expand and climate variability intensifies, understanding these sensitivities is essential for predicting ecosystem vulnerability and assessing vegetation responses to future climate scenarios.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105244"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145732138","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 : 2026-02-01Epub Date: 2025-12-22DOI: 10.1016/j.gloplacha.2025.105266
Hongxuan Lu , Weiguo Liu , Huanye Wang , Xingxing Liu , Zeke Zhang , Shugang Kang , Yitao Liu , Zheng Wang , Weijuan Sheng , Xu Liu , Youbin Sun , Zhonghui Liu
Most geological materials record temperature changes at land/ocean surface rather than air temperatures. However, whether their long-term trends exhibit coherence during the Holocene remains debated. Here, we present brGDGT-derived land surface temperature (LST) variations over the past 25 kyr in the western Chinese Loess Plateau (CLP), revealing an overall Holocene cooling trend. Modern meteorological data indicate that surface conditions critically modulate regional LSTs, allowing the surface air temperatures (SATs) to be quantitatively estimated by incorporating vegetation cover and soil moisture. The reconstructed SATs show distinct early Holocene warming, mid-Holocene thermal maximum, and late Holocene cooling, aligning well with simulated SATs and global/regional temperature reconstructions. Our findings reconcile diverging LST and SAT trends through vegetation and moisture feedbacks, offering a new method to clarify land-air thermal interactions and improve proxy-model comparisons in paleoclimatology.
{"title":"Inferring Holocene air temperatures from vegetation-corrected land temperatures","authors":"Hongxuan Lu , Weiguo Liu , Huanye Wang , Xingxing Liu , Zeke Zhang , Shugang Kang , Yitao Liu , Zheng Wang , Weijuan Sheng , Xu Liu , Youbin Sun , Zhonghui Liu","doi":"10.1016/j.gloplacha.2025.105266","DOIUrl":"10.1016/j.gloplacha.2025.105266","url":null,"abstract":"<div><div>Most geological materials record temperature changes at land/ocean surface rather than air temperatures. However, whether their long-term trends exhibit coherence during the Holocene remains debated. Here, we present brGDGT-derived land surface temperature (LST) variations over the past 25 kyr in the western Chinese Loess Plateau (CLP), revealing an overall Holocene cooling trend. Modern meteorological data indicate that surface conditions critically modulate regional LSTs, allowing the surface air temperatures (SATs) to be quantitatively estimated by incorporating vegetation cover and soil moisture. The reconstructed SATs show distinct early Holocene warming, mid-Holocene thermal maximum, and late Holocene cooling, aligning well with simulated SATs and global/regional temperature reconstructions. Our findings reconcile diverging LST and SAT trends through vegetation and moisture feedbacks, offering a new method to clarify land-air thermal interactions and improve proxy-model comparisons in paleoclimatology.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105266"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813961","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 : 2026-02-01Epub Date: 2025-12-18DOI: 10.1016/j.gloplacha.2025.105260
Qimei Guo , Yue Cai , Ahmed N. El-Barkooky , Abdel-Moneim El-Araby , Ting Ruan , Jing Liu , Anping Zou , Ahmed Zakaria , Nicholas Christie-Blick , Raed Badr
Monsoons play a pivotal role in regulating the global climate system and sustaining agricultural productivity. However, our understanding of monsoon evolution, particularly the African monsoons before the Middle Miocene, remains limited due to the paucity of relevant geological records. Well-preserved, uplifted Lower Miocene marine strata from the Gulf of Suez (GoS) basin could bridge this critical gap in paleoclimate reconstructions. Here we present, for the first time, high-resolution age model for the 20.68–19.12 Ma Nukhul Formation from the Wadi Baba area at the eastern margin of the GoS, based on nannofossil biostratigraphy, strontium isotope stratigraphy, and benthic foraminiferal δ18O records. Building upon this age framework, geochemical compositions (143Nd/144Nd, 87Sr/86Sr, and Ni/Al ratios) of fine-grained (<63 μm) silicate GoS sediments reveal an increased contribution from volcanic sources, most likely the Oligocene Ethiopian Highland volcanics, during times in which the West African summer monsoon was intensified. Such spans are hypothesized to have corresponded with an increase in the fine-grained detrital flux of the Miocene river system (MRS) in northeastern Africa from the Ethiopian Highlands to the eastern Mediterranean, and indirectly into the GoS basin. We find that, similar to records of Plio-Pleistocene West African summer monsoons and Oligo-Miocene Asian summer monsoons, Early Miocene West African summer monsoon variability was dominated by the 405-kyr eccentricity cycle, with wetter conditions during eccentricity maxima. This remarkable coherence underscores the 405-kyr eccentricity forcing as a fundamental pacemaker of tropical hydroclimate for at least the last 20 Myr, even under much warmer climate conditions like those of the Early Miocene.
{"title":"Sediment provenance and foraminiferal isotope records reveal eccentricity-paced African monsoon variability in the Early Miocene","authors":"Qimei Guo , Yue Cai , Ahmed N. El-Barkooky , Abdel-Moneim El-Araby , Ting Ruan , Jing Liu , Anping Zou , Ahmed Zakaria , Nicholas Christie-Blick , Raed Badr","doi":"10.1016/j.gloplacha.2025.105260","DOIUrl":"10.1016/j.gloplacha.2025.105260","url":null,"abstract":"<div><div>Monsoons play a pivotal role in regulating the global climate system and sustaining agricultural productivity. However, our understanding of monsoon evolution, particularly the African monsoons before the Middle Miocene, remains limited due to the paucity of relevant geological records. Well-preserved, uplifted Lower Miocene marine strata from the Gulf of Suez (GoS) basin could bridge this critical gap in paleoclimate reconstructions. Here we present, for the first time, high-resolution age model for the 20.68–19.12 Ma Nukhul Formation from the Wadi Baba area at the eastern margin of the GoS, based on nannofossil biostratigraphy, strontium isotope stratigraphy, and benthic foraminiferal δ<sup>18</sup>O records. Building upon this age framework, geochemical compositions (<sup>143</sup>Nd/<sup>144</sup>Nd, <sup>87</sup>Sr/<sup>86</sup>Sr, and Ni/Al ratios) of fine-grained (<63 μm) silicate GoS sediments reveal an increased contribution from volcanic sources, most likely the Oligocene Ethiopian Highland volcanics, during times in which the West African summer monsoon was intensified. Such spans are hypothesized to have corresponded with an increase in the fine-grained detrital flux of the Miocene river system (MRS) in northeastern Africa from the Ethiopian Highlands to the eastern Mediterranean, and indirectly into the GoS basin. We find that, similar to records of Plio-Pleistocene West African summer monsoons and Oligo-Miocene Asian summer monsoons, Early Miocene West African summer monsoon variability was dominated by the 405-kyr eccentricity cycle, with wetter conditions during eccentricity maxima. This remarkable coherence underscores the 405-kyr eccentricity forcing as a fundamental pacemaker of tropical hydroclimate for at least the last 20 Myr, even under much warmer climate conditions like those of the Early Miocene.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105260"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785313","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 : 2026-02-01Epub Date: 2025-12-15DOI: 10.1016/j.gloplacha.2025.105252
Senlin Tang , Qiang Zhang , Xintong Gong , Chong-Yu Xu , Vijay P. Singh , Fubao Sun , Yao Feng , Ziwei Li , Likun Han
Abstract
Water is vital for the sustainability of human society, and rational water resources management and effective adaptation strategies require a clear and holistic understanding of the drivers and uncertainties influencing water availability. However, the key factors and uncertainties, and their spatial heterogeneity in global water resources remain poorly quantified. Here, we employed optimal fingerprinting to identify the drivers of global water resources changes from 1980 to 2014. We found that greenhouse gas (GHG) forcing explains approximately 77.6 % of the observed upward trend, significantly outweighing the contributions from natural external forcing (NAT, 45.8 %) and aerosols (AER, −23.4 %). We evaluated the contributions of internal variability, model uncertainty, and scenario uncertainty to future global water-resource projections, and attributed ∼89.2 % of the total variance to the model uncertainty. Furthermore, by integrating historical observations (1995–2014) with the emergent constraint method, we reduced uncertainties in future projections (2081–2100) under the SSP2–4.5 and SSP5–8.5 scenarios. The constrained projections revealed the underestimation of water-resource changes by 18.0 % (SSP2–4.5) and 13.4 % (SSP5–8.5) for the 2081–2100 period. Notably, model uncertainty under both warming scenarios fell by 33.1 % and 26.4 %, respectively, substantially boosting the reliability of future projections. These findings advance our understanding of the drivers and uncertainties in global water resources, informing adaptation strategies and long-term water resources planning.
{"title":"Emergent constraints reveal underprediction of future global water availability under anthropogenic forcing","authors":"Senlin Tang , Qiang Zhang , Xintong Gong , Chong-Yu Xu , Vijay P. Singh , Fubao Sun , Yao Feng , Ziwei Li , Likun Han","doi":"10.1016/j.gloplacha.2025.105252","DOIUrl":"10.1016/j.gloplacha.2025.105252","url":null,"abstract":"<div><h3>Abstract</h3><div>Water is vital for the sustainability of human society, and rational water resources management and effective adaptation strategies require a clear and holistic understanding of the drivers and uncertainties influencing water availability. However, the key factors and uncertainties, and their spatial heterogeneity in global water resources remain poorly quantified. Here, we employed optimal fingerprinting to identify the drivers of global water resources changes from 1980 to 2014. We found that greenhouse gas (GHG) forcing explains approximately 77.6 % of the observed upward trend, significantly outweighing the contributions from natural external forcing (NAT, 45.8 %) and aerosols (AER, −23.4 %). We evaluated the contributions of internal variability, model uncertainty, and scenario uncertainty to future global water-resource projections, and attributed ∼89.2 % of the total variance to the model uncertainty. Furthermore, by integrating historical observations (1995–2014) with the emergent constraint method, we reduced uncertainties in future projections (2081–2100) under the SSP2–4.5 and SSP5–8.5 scenarios. The constrained projections revealed the underestimation of water-resource changes by 18.0 % (SSP2–4.5) and 13.4 % (SSP5–8.5) for the 2081–2100 period. Notably, model uncertainty under both warming scenarios fell by 33.1 % and 26.4 %, respectively, substantially boosting the reliability of future projections. These findings advance our understanding of the drivers and uncertainties in global water resources, informing adaptation strategies and long-term water resources planning.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105252"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785315","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}
This study evaluates the performance and uncertainties of two third-generation spectral wave models, SWAN and WW3, in simulating global wave storm characteristics, including mean and maximum storm wave heights, storm duration, and storm power. The models were forced with CMIP6-derived EC-Earth3 wind and sea ice data for 1984–2014 and validated against ERA5 reanalysis and in-situ buoy observations. Results show that SWAN model consistently underestimates storm wave height, particularly in tropical and high-energy regions, whereas WW3 aligns more closely with ERA5 but tends to overestimate storm wave heights and storm power in the Southern Ocean. Both models reproduce storm durations reasonably well, although WW3 exhibits fewer significant biases and narrower confidence intervals, reflecting higher reliability. Storm power analysis reveals SWAN's systematic underestimation and WW3's better overall performance, albeit with localized overestimations in extreme-energy basins. Comparisons with buoy data confirm WW3's improved accuracy in estimating storm durations and power, though challenges remain in replicating extreme wave heights. These findings underscore the inter-model uncertainty associated with different wave models and emphasize the need for refined wave model physics and regional calibration to improve the reliability of global wave-storm projections and better inform coastal planning and climate adaptation.
{"title":"Evaluating uncertainty in global wave storm characteristics using CMIP6-derived wave climate simulations with SWAN and WAVEWATCH III models","authors":"Rajesh Kumar , Khalid Amarouche , Adem Akpinar , Bahareh Kamranzad , Gil Lemos","doi":"10.1016/j.gloplacha.2025.105214","DOIUrl":"10.1016/j.gloplacha.2025.105214","url":null,"abstract":"<div><div>This study evaluates the performance and uncertainties of two third-generation spectral wave models, SWAN and WW3, in simulating global wave storm characteristics, including mean and maximum storm wave heights, storm duration, and storm power. The models were forced with CMIP6-derived EC-Earth3 wind and sea ice data for 1984–2014 and validated against ERA5 reanalysis and in-situ buoy observations. Results show that SWAN model consistently underestimates storm wave height, particularly in tropical and high-energy regions, whereas WW3 aligns more closely with ERA5 but tends to overestimate storm wave heights and storm power in the Southern Ocean. Both models reproduce storm durations reasonably well, although WW3 exhibits fewer significant biases and narrower confidence intervals, reflecting higher reliability. Storm power analysis reveals SWAN's systematic underestimation and WW3's better overall performance, albeit with localized overestimations in extreme-energy basins. Comparisons with buoy data confirm WW3's improved accuracy in estimating storm durations and power, though challenges remain in replicating extreme wave heights. These findings underscore the inter-model uncertainty associated with different wave models and emphasize the need for refined wave model physics and regional calibration to improve the reliability of global wave-storm projections and better inform coastal planning and climate adaptation.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105214"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690067","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 : 2026-02-01Epub Date: 2025-12-04DOI: 10.1016/j.gloplacha.2025.105229
Ke Li , Jun Tian , Ning Zhao , Jianghui Du , Zhonghui Liu , Jinlong Du , Enqing Huang
The Mid-Pleistocene Transition (MPT, 600–1300 ka) marks the shift of the dominant ice age cycle from 41-kyr to 100-kyr in the late Pleistocene. While the Atlantic Ocean circulation changes have been found to be closely linked with the MPT, the Pacific's role remains poorly constrained. Here we present fish teeth neodymium isotope (εNd) records from three sites along the Pacific Deep Western Boundary Current (DWBC) to capture the Pacific deep ocean circulation changes on Glacial-Interglacial (G-IG) timescale during the MPT. We found reduced deep water εNd gradient (ΔεNd) between north and south Pacific during glacial periods. After constraining non-conservative influences on εNd, we infer that enhanced northward expansion of Southern Component Water (SCW) and/or shoaling of the Pacific Deep Water (PDW)-Lower Circumpolar Deep Water (LCDW) interface best explain the observed patterns. While the G-IG variability of the ΔεNd is largely consistent throughout the MPT, indicating a generally stable rhythm of Pacific deep overturning circulation, the pronounced εNd values of the three Pacific sites during Marine Isotope Stage (MIS) 22 suggest a transient circulation anomaly. The rigorous Pacific deep ocean circulation enhanced the ocean carbon storage through surface disequilibrium during glacials. Our results indicate that ocean circulation has played an important role in shaping the late Pleistocene ice ages through interaction with carbon cycle.
{"title":"Stable Pacific deep circulation punctuated by episodic intensification during the Mid-Pleistocene Transition","authors":"Ke Li , Jun Tian , Ning Zhao , Jianghui Du , Zhonghui Liu , Jinlong Du , Enqing Huang","doi":"10.1016/j.gloplacha.2025.105229","DOIUrl":"10.1016/j.gloplacha.2025.105229","url":null,"abstract":"<div><div>The Mid-Pleistocene Transition (MPT, 600–1300 ka) marks the shift of the dominant ice age cycle from 41-kyr to 100-kyr in the late Pleistocene. While the Atlantic Ocean circulation changes have been found to be closely linked with the MPT, the Pacific's role remains poorly constrained. Here we present fish teeth neodymium isotope (ε<sub>Nd</sub>) records from three sites along the Pacific Deep Western Boundary Current (DWBC) to capture the Pacific deep ocean circulation changes on Glacial-Interglacial (G-IG) timescale during the MPT. We found reduced deep water ε<sub>Nd</sub> gradient (Δε<sub>Nd</sub>) between north and south Pacific during glacial periods. After constraining non-conservative influences on ε<sub>Nd</sub>, we infer that enhanced northward expansion of Southern Component Water (SCW) and/or shoaling of the Pacific Deep Water (PDW)-Lower Circumpolar Deep Water (LCDW) interface best explain the observed patterns. While the G-IG variability of the Δε<sub>Nd</sub> is largely consistent throughout the MPT, indicating a generally stable rhythm of Pacific deep overturning circulation, the pronounced ε<sub>Nd</sub> values of the three Pacific sites during Marine Isotope Stage (MIS) 22 suggest a transient circulation anomaly. The rigorous Pacific deep ocean circulation enhanced the ocean carbon storage through surface disequilibrium during glacials. Our results indicate that ocean circulation has played an important role in shaping the late Pleistocene ice ages through interaction with carbon cycle.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"257 ","pages":"Article 105229"},"PeriodicalIF":4.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690068","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}
The 4.2 ka event is traditionally viewed as a megadrought that contributed to the demise of ancient civilizations and marks the mid-to-late Holocene boundary. However, its spatiotemporal consistency and underlying drivers remain unresolved, rendering it a contentious topic. Here, we present a precisely dated and highly resolved stalagmite multiproxy record from East Asia, derived from petrographic (calcite versus aragonite) and geochemical analyses. Our results demonstrate that the 4.2 ka event consisted of three distinct hydroclimatic intervals: an initial arid interval from 4.55 to 4.25 ka BP, a subsequent non-arid interval from 4.25 to 3.86 ka BP, and a final arid interval from 3.86 to 3.73 ka BP. This tripartite structure challenges the long-standing paradigm that the event was uniformly arid or humid. Notably, the middle non-arid interval in East Asia coincided with the canonical arid 4.2 ka event documented across the Mediterranean region, indicating a dynamic climatic teleconnection between these two regions. The non-arid interval in East Asia and the contemporaneous arid 4.2 ka event across the Mediterranean correspond to a cold Pacific Decadal Oscillation (PDO) phase. In contrast, the two arid intervals in East Asia that have no clear counterparts in the Mediterranean region coincide with warm PDO phases. This pattern implies that tropical forcing was likely a key driver of the canonical 4.2 ka event across the Mediterranean and exerted a sustained influence on the East Asia hydroclimate around this period. Our study offers a comprehensive multiproxy framework for re-evaluating the spatial manifestations and driving mechanisms of the 4.2 ka event.
4.2 ka事件传统上被认为是导致古代文明消亡的一次特大灾害，标志着全新世中晚期的分界线。然而，其时空一致性和潜在驱动因素仍未解决，使其成为一个有争议的话题。本文通过岩石学（方解石与文石）和地球化学分析，提出了一份精确年代和高度分辨率的东亚石笋多代记录。结果表明，4.2 ka事件由3个不同的水文气候区间组成：4.55 ~ 4.25 ka BP的初始干旱区间、4.25 ~ 3.86 ka BP的非干旱区间和3.86 ~ 3.73 ka BP的最终干旱区间。这种三重结构挑战了长期以来的范式，即事件是均匀干旱或潮湿的。值得注意的是，东亚的中期非干旱期与地中海地区记录的4.2 ka典型干旱事件相吻合，表明这两个地区之间存在动态的气候遥相关。东亚非干旱期和同期地中海干旱4.2 ka事件对应一个冷太平洋年代际涛动（PDO）期。相比之下，东亚的两个干旱期在地中海地区没有明显对应，却与温暖的PDO相一致。这一模式表明，热带强迫可能是4.2 ka地中海典型事件的关键驱动因素，并在此期间对东亚水文气候产生了持续影响。我们的研究为重新评估4.2 ka事件的空间表现和驱动机制提供了一个综合的多代理框架。
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Pub Date : 2026-02-01Epub Date: 2025-12-14DOI: 10.1016/j.gloplacha.2025.105253
Shulin Deng , Xuanhua Song , Chunhua Lu , Menglan Lu , Tan Chen , Ni Yang
Changes in seasonal distributions of rainfall have far-reaching impacts on agriculture production, freshwater resource management, and sustainable socio-economic development. Previous studies suggested that rainfall seasonality become stronger in many parts of the world during recent decades, however, whether and how human activities affect rainfall seasonality changes is largely unclear. Here, we analyzed the impacts of anthropogenic forcing on rainfall seasonality changes and underlying physical mechanisms in global land monsoon (GM) regions. The results from both the observations and historical simulations show that rainfall seasonality significantly enhances in South American, South African, North African, and South Asian monsoon regions. The enhanced rainfall seasonality and amplified risk of extreme seasonality can be confidently attributed to anthropogenic forcing in these regions, but the contributions of greenhouse gas (GHG) and anthropogenic aerosols (AER) forcings to rainfall seasonality changes vary in different regions. Further moisture budget analysis reveals that the GHG-forced thermodynamic term of vertical moisture advection, AER-forced dynamic term of vertical moisture advection, or both dominate the magnitudes and directions of rainfall trends in months during the beginning, middle, or late of local wet season, and thus alter rainfall concentration of wet season and rainfall magnitude and finally enhance rainfall seasonality in South American, North African, South African, and South Asian monsoon regions. These findings provide more reliable evidence that the enhanced rainfall seasonality in much of GM regions is attributable to anthropogenic climate change, suggesting that both GHG and AER emissions reductions are urgently needed to mitigate rainfall seasonality changes in the future.
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Pub Date : 2026-02-01Epub Date: 2025-12-18DOI: 10.1016/j.gloplacha.2025.105259
Dahua Huang , Kefu Yu , Leilei Jiang , Wei Jiang
The El Niño–Southern Oscillation (ENSO) dominates global interannual climate variability and significantly impacts human societies. However, ENSO behavior during the Holocene remains poorly constrained and debated, limiting our ability to assess its long-term dynamics. Here, we present a 2203-year, discontinuous record of annual coral growth rates, derived from 113 U-series-dated fossil corals (Porites lutea) collected from eastern Hainan Island in the northern South China Sea (SCS), spanning 5829–2643 years before present (a BP, relative to 1950 Common Era [CE]). Using a robust calibration between coral growth rate and sea surface temperature (SST), we quantitatively reconstruct annual SST fluctuations in the northern SCS, ranging from 24.2 °C to 27.5 °C, with a mean of 25.6 ± 0.4 °C (1σ), approximately 0.7 °C lower than the baseline of 1982–2023 CE. The SST record reveals at least 18 cold periods occurring quasi-periodically at ∼200-year intervals, with their durations shortening toward the Late Holocene. Since coral growth rates closely track local SST variability, interannual ENSO signals are reliably preserved in the coral archive. The inferred ENSO variability exhibits pronounced multidecadal modulation, transitioning from weaker-than-present, persistent La Niña-like conditions in the Mid-Holocene (∼5800–4200 a BP) to stronger-than-present, prolonged El Niño-like conditions in the Late Holocene (∼4200–2600 a BP). These ENSO shifts cannot be fully explained by external forcings such as orbital insolation or volcanic activity, highlighting the predominant role of internal ocean–atmosphere dynamics in modulating ENSO evolution during the Holocene.
El Niño-Southern涛动（ENSO）主导着全球年际气候变率，并对人类社会产生重大影响。然而，ENSO在全新世期间的行为仍然缺乏限制和争论，限制了我们评估其长期动态的能力。本文利用在南海北部海南岛东部采集的113个u系列年代的珊瑚化石（Porites lutea），对2203年的珊瑚年生长率进行了间断记录，时间跨度为距今5829-2643年（一个BP，相对于1950 Common Era [CE]）。利用珊瑚生长速率和海表温度（SST）之间的稳健校准，我们定量地重建了南海北部海表温度的年波动，范围为24.2°C至27.5°C，平均为25.6±0.4°C (1σ)，比1982-2023 CE的基线低约0.7°C。海温记录显示，至少有18个冷期以准周期性的方式出现，间隔为200年，其持续时间向晚全新世方向缩短。由于珊瑚的生长速度与当地海温的变化密切相关，年际ENSO信号被可靠地保存在珊瑚档案中。推断的ENSO变率表现出明显的多年代变，从全新世中期（~ 5800-4200 a BP）弱于现在的持续La Niña-like条件过渡到全新世晚期（~ 4200-2600 a BP）强于现在的持续El Niño-like条件。这些ENSO变化不能完全用轨道日照或火山活动等外部强迫来解释，这突出了全新世期间内部海洋-大气动力学在调节ENSO演变中的主导作用。
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