Three phases of archaeological investigations have been conducted in the area of the City Museum of Novi Sad at the Petrovaradin Fortress. In this study, we summarize the results of geoarchaeological research carried out during the third phase of excavations inside the museum building. The investigated area covered 27 m2. The approximately 0.60 m thick loessic sequence offers a unique opportunity to reconstruct the environmental evolution of this area during the last glacial period. In sectors inside of the City Museum of Novi Sad, artefacts from the Upper Palaeolithic (Gravettian) were discovered. The analysed paleoenvironmental proxies (magnetic, geochemical, and colour proxies) largely indicate similarities with the uppermost three units of previously studied sections and with the Late Pleniglacial loess unit in nearby loess profiles in Petrovaradin and Mi & scaron;eluk. This chronostratigraphic interpretation, suggesting that the profile most likely formed during the Marine Isotope Stage (MIS) 2 and possibly the youngest part of MIS 3, is supported by one radiocarbon date. The identified mollusc assemblages indicate relatively humid and cold environmental conditions in the upper part of the section. These results suggest that the northern slopes of Fru & scaron;ka Gora Mountain played an important environmental role during the Late Pleistocene. Up to 12 different mollusc species per sample were identified, favouring both steppe and forest-like vegetation. This environmental diversity, combined with favourable strategic factors, may have influenced the human occupation in the area. Im Bereich des Stadtmuseums Novi Sad auf der Festung Petrovaradin wurden drei Phasen arch & auml;ologischer Untersuchungen durchgef & uuml;hrt. Der vorliegende Beitrag fasst die Ergebnisse der geoarch & auml;ologischen Forschungen zusammen, die w & auml;hrend der dritten Grabungsphase im Inneren des Museumsgeb & auml;udes erfolgten. Die untersuchte Fl & auml;che umfasste 27 m2. Die etwa 0,60 m m & auml;chtige l & ouml;ssartige Sedimentabfolge bietet eine seltene Gelegenheit, die Umweltentwicklung dieses Gebietes w & auml;hrend des letzten Glazials zu rekonstruieren. In den Bereichen innerhalb des Stadtmuseums Novi Sad wurden Artefakte aus dem Jungpal & auml;olithikum (Gravettien) geborgen. Die analysierten Pal & auml;oumwelt-Proxy-Daten (magnetische, geochemische sowie farbmetrische Parameter) zeigen weitgehende & Uuml;bereinstimmungen mit den obersten drei Einheiten zuvor untersuchter Profile sowie mit der sp & auml;tpleniglazialen L & ouml;sseinheit benachbarter L & ouml;ssprofile in Petrovaradin und Mi & scaron;eluk. Diese chronostratigraphische Einordnung, der zufolge die Profilbildung h & ouml;chstwahrscheinlich w & auml;hrend der marinen Sauerstoffisotopenstufe (MIS) 2 und m & ouml;glicherweise im j & uuml;ngsten Abschnitt von MIS 3 erfolgte, wird durch ein Radiokarbondatum gest & uuml;tzt. Die identifizierten Mollusken-Assoziationen weisen im oberen Profilabschnitt auf relativ feuchte und kalte Umweltbedingungen hin. Die Ergebnisse deuten darauf hin, dass die Nordh & auml;nge des Fru & scaron;ka gora-Gebirges im Sp & auml;tpleistoz & auml;n eine bedeutende & ouml;kologische Rolle spielten. Pro Probe wurden bis zu zw & ouml;lf Molluskenarten nachgewiesen, die sowohl an Steppen- als auch an wald & auml;hnliche Vegetationsbedingungen angepasst sind. Diese Umweltdiversit & auml;t in Kombination mit g & uuml;nstigen strategischen Faktoren k & ouml;nnte die menschliche Besiedlung des Gebietes beg & uuml;nstigt haben.

The northern boundary of the East Asian Summer Monsoon (EASM) is a crucial area for studying how regional climate responds to global change, yet its paleotemperature history since the last deglaciation remains poorly understood. Here, we present a high-resolution reconstruction of month-above-freezing temperatures (MAFT) over the past 15,000 years, based on branched glycerol dialkyl glycerol tetraethers from Lake Shuanggoushan, a crater lake situated at the northern edge of the EASM. Our MAFT record reveals major climatic transitions, including a 1.6 degrees C warming during the B & oslash;lling-Aller & oslash;d (14.6-12.8 ka BP), a subsequent 1.8 degrees C cooling in the Younger Dryas (12.8-11.7 ka BP), a gradual warming into the mid-Holocene (11.7-7 ka BP), and a persistent cooling trend from 7 ka BP to the present. These variations are generally consistent with temperature reconstructions from the broader EASM region and the Northern Hemisphere. Mechanistic analyses indicate that the warming from the last deglaciation to the mid-Holocene (15-7 ka BP) was primarily driven by increasing summer insolation in the Northern Hemisphere, further modulated by ice-sheet retreat and a weakened Atlantic Meridional Overturning Circulation. During the interval of 11.7-7 ka BP, enhanced volcanic activity likely exerted a regional cooling influence, partially offsetting the intense summer insolation at 45 degrees N. The long-term cooling since the 7 ka BP was mainly driven by declining summer insolation and a strengthened East Asia Winter Monsoon. Furthermore, spectral analysis of the MAFT time series identifies significant periodicities at 250, 83, and similar to 60 years (99 % confidence), which correspond to known solar cycles, reinforcing the role of solar forcing in regional temperature variability. Overall, these findings suggest that the temperature evolution at this climate-sensitive monsoon boundary results from the interplay of summer insolation changes in the Northern Hemisphere, ice sheet dynamics, monsoon strength, ocean circulation, and volcanic activity.

The lack of reliable proxies capturing multi-seasonal interactions limits our understanding of long-term seasonal succession patterns. Lake diatoms, being sensitive to seasonal climate changes, serve as a valuable proxy for reconstructing seasonal variability. However, extracting seasonal phenological signals from multi-year sediment records remains challenging. Conducting continuous multi-year, monthly-to-seasonal modern diatom investigations using sediment traps is a crucial approach to validate their applicability for long-term seasonal reconstruction. This study revisited the subtropical alpine Yunlong Lake in the monsoon region of southwestern China, conducting two additional years (May 2021 to April 2023) of monthly trap monitoring following prior research (September 2013 to August 2015). Integrated with concurrent meteorological, hydrological, and hydrochemical data, we systematically analyzed seasonal diatom dynamics and their climatic implications. Key results include: (1) Marked interannual differences in diatom assemblage composition. Benthic diatoms dominated in the second year, while planktonic taxa decreased significantly. This shift was driven by largely-reduced warm-season rainfall, which led to lower water levels, expanded benthic habitats, and increased light availability. Thus, the planktonic-to-benthic diatom ratio serves as a sensitive indicator of long-term monsoon precipitation variability. (2) Principal component analysis revealed pronounced seasonal succession patterns among planktonic diatoms, particularly during high-water-level periods in the first year. During warm seasons (May to November), Achnanthidium catenatum and Aulacoseira granulata var. angustissima showed cyclic recurrent blooms. In the cold season (December to April) of the first year, a sequential proliferation of planktonic taxa - from larger forms (Aulacoseira ambigua, Discostella asterocostata) to smaller ones (Discostella stelligera, Lindavia balatonis, and Discostella pseudostelligera) - was observed, consistent with earlier findings. These dynamics were regulated by temperature-mediated shifts in mixing-stratification regimes and nutrient availability, indicating that water temperature directly and/or indirectly controls seasonal diatom succession. Overall, these results demonstrate that diatom assemblages in Yunlong Lake effectively reflect cyclic seasonal climate variations in monsoon regions.

To elucidate the relative influences of different-scale forcing factors on climate change, in particular on relative aridity, we developed a 40,000-year-long record of lake-level fluctuations using the high-resolution sedimentary archive from Huguangyan Maar Lake (HML) in the Leizhou Peninsula, southern China. Analyses on grain size and total organic matter revealed that lake levels were the lowest during the Last Glacial Maximum (LGM), while minor variations occurred during Heinrich events, and more pronounced oscillations characterized the Younger Dryas (YD). Following the YD, lake levels gradually recovered, peaking around 8000 years ago before declining to present-day levels. Our data unequivocally demonstrate that the lake-level decline during the LGM was the most extreme observed throughout the 40,000-year long record, exceeding the magnitude of other millennial-scale climate events. Crucially, despite orbital forcing imposing two distinct periods of both minimum and maximum solar insolation over the 40,000 year-long intervals, the drastic hydrological changes—total desiccation and peak water levels—each occurred only once. Total desiccation uniquely coincided with the LGM, while peak water levels were confined to the early-middle Holocene. These findings suggest that while variations in solar insolation and the Atlantic Meridional Overturning Circulation (AMOC) modulate monsoon rainfall, the extensive glacial expansion during the LGM played a significant role in southern China's extreme aridity. The LGM thus represents the driest period in southern China over the past 40,000 years, indicating that this pronounced aridity resulted from the synergistic interplay of large ice volume and low solar insolation.

Environmental reconstruction at the site level is crucial for gaining a nuanced understanding of human-environment interactions in prehistoric period. The Haimenkou wetland archaeological site, located on the Yunnan Plateau in Southwest China, offers an opportunity to investigate how local environmental conditions have changed since the late Pleistocene and how humans adapted to and modified these landscapes over time. This study employs a multi-proxy approach to reconstruct the sedimentary history and physical environment surrounding the site. Our results indicate that before human occupation, Neotectonic activity and climatic fluctuations played the most significant roles in shaping the land surface. The Jianchuan Basin, where Haimenkou is situated, underwent considerable geomorphological changes driven by these natural forces, including shifting lake levels and erosional processes. However, once human settlement began, anthropogenic activities-such as forest clearance, agriculture, and the expansion of settlements-became the dominant forces altering the environment. The findings also have broader implications for understanding the "Missing Millennia"-a term used to describe the scarcity of archaeological sites from the Mid-Holocene across Southwest China and mainland Southeast Asia. Our research suggests that active erosion, sediment transport, and redeposition during this period likely played a significant role in the poor preservation of archaeological remains.

The B & oslash;lling-Aller & oslash;d (B-A) interstadial (similar to 14.7-12.85 cal ka BP), the most important warming event of the last deglaciation in the northern hemisphere, is a key time window to study how precipitation changes under the background of rapid warming. However, the relationship between precipitation changes and rapid warming during the B-A interstadial in Northeast (NE) China has remained unclear. Here, we present a multiproxy record spanning the interval 20-10 cal ka BP from a small volcanic lake in NE China and compare it with other records from the same region to clarify the hydroclimatological history of the last deglaciation in NE China. The results suggest that precipitation lagged behind temperature increase during the B-A interstadial in NE China. We attribute this lag to the different forcings at play on the evolution of precipitation and temperature during the B-A, in which the temperature changes were forced by the recovery of the Atlantic Meridional Overturning Circulation and the triggered release of stored heat in the North Atlantic from the high latitudes while the precipitation changes were controlled by increasing sea surface temperatures in the low latitudes.

Acidification is a major ecological problem in a large number of lakes around the world. In recent decades, research has primarily focused on the effects of human-induced acid deposition on lake ecosystems. However, there has been relatively little research on how changes in the natural environment influence the acid-base balance of lakes. In this study, we tracked the changes of lake acidity in the past similar to 10,000 years by using the records of sedimentary diatoms in Buteha Lake, a volcanic lake in northeast China. We also compare the historical changes in lake acidity with variations in vegetation and aeolian activity recorded in the same core and regional data to evaluate the relationships among lake acidity, vegetation changes, and dust deposition. The diatom results show that during the mid-Holocene (8200-4500 cal yr BP), acid-tolerant diatoms (Eunotia species) were very abundant. This pattern was followed by a gradual decline during the late Holocene, with a slight increase observed in recent decades. Proliferation of acid-tolerant diatoms indicate that severe lake acidification occurred during the mid-Holocene. The trend of lake acidification closely resembles the regional vegetation changes, contrasting with the intensity of aeolian activity. Our results suggest that lake acidification in the mid-Holocene was not directly linked to change in temperature and/or precipitation, but rather was driven by the balance between acidic and alkaline substance inputs. Specifically, climate warming and stronger monsoons enhanced terrestrial vegetation, increasing acidic humic substance inputs to the lake, while decreased alkaline dust deposition synergistically exacerbated acidification. This study provides a scientific basis for predicting the future development of lake environment in northeast China, and offers valuable insights for environmental research on natural lakes acidification globally. We predict that if global warming continues and precipitation increases in the future, more lakes, especially those that depend on dust inputs to maintain their acid neutralizing capacity, may experience acidification due to the decrease of alkaline dust deposition and the increase of acidic humic substances input caused by vegetation expansion.

The impact of rapid climate change on civilizations is of global concern. The Western Zhou (1045-771 BC) was ancient China's third dynasty and one of the most powerful empires of its time. After a 274-year reign, the dynasty collapsed, accompanied by significant population migration. Various factors have been proposed to explain its fall, while the role of climate change has been largely ignored. Here we present well-dated, high-resolution stalagmite records from Northeast and Southeast China, along with other paleoclimatic and archaeological evidence, to demonstrate the critical role of the 2.8 ka climatic event in the dynasty's collapse and subsequent migration. Our results indicate a "north dry-south wet" dipolar pattern in the Chinese monsoon region during this event. The drought and cold severely affected the Western Zhou core areas and exacerbated invasions by northern nomads, contributing to its collapse. The resulting environmental stresses and conflicts likely triggered substantial southward migration.

Seasonal temperature reconstructions provide a critical approach for reconciling discrepancies between paleoclimate model simulations and proxy records. However, cold-season temperature variations remain poorly constrained due to the scarcity of robust cold-season temperature proxies. This study provides critical insights into lake ice-covered season temperature dynamics in Northeast China, a region where cold-season climate variability has remained poorly constrained in paleoclimate reconstructions. We collected total organic carbon sequences from seven closed lakes in Northeast China over the last 10,000 years to evaluate the lake ice cover duration as a proxy for lake ice-covered season temperature during the early–middle Holocene. Our results show that the lake ice cover duration decreased from ~8 ka BP, reaching a minimum at around 4 ka BP. This pattern is linked to ice-covered season temperature changes, with warmer ice-covered seasons leading to shorter ice cover durations and increased lake productivity, which were driven by orbital forcing (seasonal insolation changes) and greenhouse gas concentrations. Orbital forcing played a dominant role in winter warming between 8 and 4 ka BP, while greenhouse gas also contributed, but to a lesser extent.

Since the onset of post-industrial global warming, there remains significant controversy over whether the evolution of the Indian Monsoon has deviated from the natural baseline of 'rainfall and heat synchronization'. This question requires a deep understanding of the long-term correlation between temperature and monsoon rainfall changes. We selected Yunlong Lake, a climate-sensitive subalpine lake located on the southeastern margin of the Tibetan Plateau, to study this issue. We semi-quantitatively revealed warm-season temperature changes using the relative abundance of warm-preference planktic diatoms, namely Achnanthidium catenatum and Aulacoseira granulata var. angustissima, found in our diatom seasonal survey. Meanwhile, by examining the spatial pattern of surface diatom assemblages along the water depth gradient, two diatom-water depth transfer functions were constructed by using the modern analogue technique (MAT) and weighted average partial least squares regression (WAPLS) method, which were used to quantitatively reconstruct past lake water level changes. Comparison with independent modern monitoring records, the warm-water diatom indicators and the two diatom transfer functions suggest to be sensitive and reliable for reconstructing long-term temperature and rainfall changes in the Indian Monsoon domain. Based on this, and relying on the complete Holocene sedimentary records from the profundal zone of the lake, we reconstructed the warm-season temperature changes and lake water level fluctuations during the Holocene. Our reconstruction indicates that the temperature and rainfall in the Indian Monsoon domain exhibit a synchronous, 'three-stage' stepwise change over the multimillennial scale of the Holocene. These stages are roughly marked by the climate events of 8.2 ka and 4.2 ka, with the maximum warm-season temperature and lake water level occurring during the middle Holocene. We find that the maximum rainfall and heat during the middle Holocene in this region roughly coincide with the peak of warm-season (summer-autumn) insolation. This may be related to the significant thermal difference between land and ocean at that time, suggesting a synchronous change in rainfall and temperature in Indian Monsoon domain over long timescales.

Understanding regional paleotemperature changes over the past 2000 years is crucial for global climate networks, as it provides valuable insights into climate dynamics and offers a regional perspective within the global system. In this study, we present a high-resolution temperature reconstruction (similar to 10-year resolution) for the past two millennia, using branched dialkyl glycerol tetraethers (brGDGTs) from the laminated sediments of Lake Shuanggoushan in Northeast China. Our reconstruction of month-above-freezing temperatures (MAFT) revealed significant temperature variability on decadal to centennial timescales, which aligns well with other paleotemperature records from Northeast China but diverges from the composite temperature series of the broader Chinese region. In this region, instrumental records revealed a strong positive correlation between the Arctic Oscillation (AO) and winter-spring temperatures (Nov-Apr), with a weaker correlation during the ice-free season (May-Oct). Paleoclimate records further demonstrate a weak positive correlation (r = 0.22, p < 0.01) between the AO index and MAFTs on decadal timescales, suggesting that the AO has influenced regional temperature variability over the past 2000 years. Spectral analysis of the temperature time series identified two periodicities (55-57 and 66-67 years) with 99 % confidence, which closely align with the similar to 60-year solar cycle. This finding indicated a possible link between temperature variability and solar activity. Overall, our results highlight the significance of the AO and solar activity in driving decadal temperature variability during ice-free seasons in Northeast China over the past two millennia.

Known as the “Holocene temperature conundrum”, controversy remains between paleoclimate reconstructions indicating cooling during the late-Holocene versus model simulations indicating warming. Here, we present a composite Holocene winter temperature index record derived from East Asian winter monsoon (EAWM) reconstructions. This new temperature index record documents a thermal maximum occurring during the mid-Holocene, followed by a cooling trend. Along with other Holocene winter temperature reconstructions, these findings collectively indicate a cooling trend during the late-Holocene, consistent with global annual average temperature reconstructions. Notably, our composite dust records and dust sensitivity simulations identified enhanced global aeolian dust, which has been overlooked in previous model simulations, as a likely driver of the cooling trend throughout the mid- to late-Holocene. Our new evidence does not support the current seasonal bias explanation of the Holocene temperature controversy, but instead suggests potential mechanisms that could help explain the differences between temperatures inferred from models and paleo-reconstructions in the past.

A fundamental aspect of marine benthic foraminiferal δ18O records of the last one million years is their “saw-tooth” pattern, characterized by gradual cooling to full glacial conditions followed by very rapid glacial terminations. Understanding the mechanism of this pattern is crucial for understanding ice age dynamics. We investigated the climatic trend within each glacial of the last 880 kyr by comparing the signal of the East Asian winter monsoon (EAWM) with global terrestrial and marine paleoclimate records. Our new grain size record from the Huining loess-paleosol section in the western Chinese Loess Plateau, together with published climate records from the Yimaguan and Luochuan sections in the central Chinese Loess Plateau, demonstrates a strengthening trend of the EAWM within most glacials, which largely mirrors the “saw-tooth” pattern of the benthic foraminiferal δ18O record. However, the EAWM record during Marine Isotope Stage (MIS) 8 shows an unusual weakening trend which is the exception over the last 880 kyr. Based on the linkages between Arctic ice sheets, the Siberian High Pressure system, and the EAWM, we propose that the weakening trend of the EAWM throughout MIS 8 reflects the overall shrinking of Arctic ice sheets towards the glacial termination, in contrast to the increasing trend of the benthic foraminiferal δ18O values. This conclusion is supported by a compilation of global paleoclimate records suggesting that MIS 8 was a unique glacial period over the last 900 kyr, characterized by a mild climate in middle to high northern latitudes and a cold climate in high southern latitudes, during late MIS 8. The inferred changes in Arctic ice sheets would alone cause a decreasing trend in benthic foraminiferal δ18O values during MIS 8, which is the opposite to the observed trend. We suggest that an increased ice volume in high southern latitudes led to the cooling of Antarctic Bottom Water and hence to a decrease in ocean bottom water temperature with an effect to increase benthic foraminiferal δ18O during MIS 8 as observed. Our results highlight the complexity of using the benthic δ18O signal alone as a paleoclimate proxy, and that MIS 8 is an important time window for better understanding glacial dynamics driven by changes in the polar regions of both hemispheres.

Past intervals of warming provide the unique opportunity to observe how the East Asia monsoon precipitation response happened in a warming world. However, the available evaluations are primarily limited to the last glacial-to-interglacial warming, which has fundamental differences from the current interglacial warming, particularly in changes in ice volume. Comparative paleoclimate studies of earlier warm interglacial periods can provide more realistic analogs. Here, we present high-resolution quantitative reconstructions of temperature and precipitation from north-central China over the past 800 thousand years. We found that the average precipitation increase, estimated by the interglacial data, was only around one-half of that estimated for the glacial-to-interglacial data, which is attributed to the amplification of climate change by ice volume variations. Analysis of the interglacial data suggests an increase in monsoon precipitation of ~100 mm for a warming level of 2°C on the Chinese Loess Plateau.

The aeolian sediments in the Central Shandong Mountains (CSM) in eastern China provide a faithful carrier of climate and sea-level variations outside of the Chinese Loess Plateau. However, due to the lack of or limited application of absolute dating protocols, previous studies of Shandong loess have focused mainly on loess deposited since the last interglacial period, with fewer studies on provenances and climate changes recorded in older penultimate interglacial period characterized by a long duration and significant climate fluctuations, which is not helpful to understand the spatiotemporal pattern changes of East Asian monsoon. In this study, multielevated-temperature post-infrared infrared-stimulated luminescence (MET-pIRIR) dating method was utilized to obtain the absolute ages from the Dongheishan (DHS) section in CSM region. Preheat plateau and dose recovery tests indicate that the MET-pIRIR signals of 250 degrees C and 300 degrees C have negligible anomalous fading and they can give reliable ages for the loess since-270 ka. Luminescence dating results suggest that the DHS loess mainly accumulated from 265 +/- 12 ka to 93 +/- 4 ka. The loess sedimentation rates during-195 +/- 18 -108 +/- 4 ka were much lower than expected in the DHS section, which occurred approximately correlates with the Qingshui erosion period (-136 ka), as indicated by the planation surface outside the CSM. Both the grain-size characteristics and sedimentation rate variations suggest that the dust sources of the DHS loess were primarily proximal sediments, which is possibly due to frequent variations in dust provenances caused by plentiful precipitation during the interglacial periods and diversions of the Yellow River. This study implies that the CSM loess with a good chronology could be utilized to decipher regional sedimentation and climatic changes processes.

The future impact of global warming on tropical arid regions is unclear due to uncertainties about the correlation between rising temperatures and changes in precipitation patterns. A critical factor is the reliability of the sedimentary chronologies. Hence, to better understand the potential long-term consequences of climatic warming or cooling for tropical arid regions we compared a pollen record from the annually-laminated sediments of a crater lake in Myanmar with ice core records of the Siberian High, both of which have an annual resolution. Our findings reveal that over the past 8000 years, the Myanmar region experienced six significant drought events, three of which coincided precisely with intensifications of the Siberian High-pressure system. Furthermore, five out of these six events were synchronous with the North Atlantic Bond events within the limit of the dating uncertainties. Conversely, warm periods were associated with increased precipitation along with relatively short-lived drought events. Our findings suggest that regardless of the El Niño intensity, a cooling trend in the Northern Hemisphere may result in persistent extreme drought conditions in arid tropical regions. Therefore, as well as the environmental implications of global warming, it is also important to address the potential hazards associated with cooling, especially in arid tropical regions. To facilitate effective disaster management and to develop strategies for climate change mitigation, it is crucial to better understand the complex relationship between temperature fluctuations and drought. Overall, our findings are a reminder of the importance of not ignoring the potential disasters that may arise from cooling trends while focusing exclusively on warming.

The last deglaciation is considered a key period for exploring the underlying dynamics of temperature changes because it was characterized by multiple millennial-scale abrupt climatic events. However, the limited number of quantitative temperature records in Northeast (NE) China covering the last deglaciation hampers a complete understanding of the mechanisms and processes behind the temperature changes that occurred in that region. Here, we present a quantitative reconstruction of summer temperature over the last deglaciation based on bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) analyzed from the sediment sequence of Lake Kielguo, a small volcanic lake in NE China. The results show that summer temperature was lowest during the interval ca. 20-18.2 calibrated (cal.) k.y. B.P. with a value of similar to 11.1 degrees C and increased by similar to 1.9 degrees C during Heinrich Stadial 1 (HS1) and by similar to 2.7 degrees C during the transition to the Bolling-Allerod (B-A). The summer temperatures during the B-A warm interval and Younger Dryas cold interval were similar to 14.1 degrees C and similar to 12.0 degrees C, respectively. The summer temperature record from the Lake Kielguo sediment sequence indicates that summer warming dominated the climate change state during HS1 in East Asia, which is different from the cooling pattern controlled by winter temperatures in the North Atlantic and Greenland realms. This distinction can be explained by weakened winter cooling signals triggered by the collapse of Atlantic Meridional Overturning Circulation when these signals propagated to East Asia, and increased summer temperature warming controlled by orbital and greenhouse gases during HS1 in East Asia.

Temperature reconstruction over the past two millennia has created a crucial database for global networks and for evaluating and predicting global climate change. Here, we present a high-resolution (~5-25 years) temperature reconstruction over the past 2000 years using branched glycerol dialkyl glycerol tetraethers (brGDGTs) from laminated sediments in a crater lake located in Northeast China. The brGDGT-derived proxies accurately represented the month-above-freezing temperatures (MAFT) within our study region. Our temperature reconstruction exhibited distinct decadal-to-centennial variability and showed rough correspondence with the AO/NAO index and solar activity. Furthermore, the spectral analysis identified two quasi-periodicities of 55-57 and 66-67 years within the MAFTs time series at a 99% confidence level, suggesting possible associations with solar activity. These findings imply that long-term temperature variability in Northeast China is mainly regulated by a combination of the AO, NAO, and solar activity.

全新世(11.7 ka BP)作为最年轻的地质年代,其气候变化相对晚更新世冰期稳定,但仍存在千百年尺度的气候波动.造成这些气候波动的可能有多种原因,但至今还没有统一的认识.这一时期的气候变化与人类发展有密切的关系,因此其短尺度的气候变化越来越受到学界的关注,已经开展了大量的研究.通过对文献资料分析,综述了全新世千百年尺度的气候突变的原因.全新世早期温度普遍升高主要与太阳活动变化有关,期间冰盖消融与海洋环流作用引起百年尺度的气候事件.全新世中期气温最高,但也发现多次干冷气候事件,主要为冰川活动导致.全新世晚期温度降低,主要是以火山活动导致的气候变冷.其他因素如地球轨道参数、潮汐作用、冰川作用、海洋环流等在全新世各个时期对气候造成影响.

The North Atlantic jet stream (NAJ) has a profound impact on the climate of the North Atlantic-European sector, especially in winter. Observations show that the winter NAJ (NAJw) has strengthened over the past similar to 140 yr. However, it remains unclear whether this long-term trend has deviated from the natural variability. Here, we present a 2500-yr-long reconstruction of NAJw strength using high-quality stalagmite delta 18O records from southeastern Europe. Our results show that the NAJw weakened during both the Roman Warm Period (300 B.C.- A.D. 200) and the Medieval Warm Period (A.D. 900-1250) but that it has strengthened under anthropogenic warming (since A.D. 1850). This indicates that its current trend has already deviated from the natural variability. The best explanation for this present anomalous trend of NAJw strength is that it was triggered by the appearance of the North Atlantic warming hole under anthropogenic forcing. This anomalous trend suggests that continued global warming may further strengthen the NAJw in the future.