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Based on the climate proxy data, several recent studies have concluded that the Ming dynasty's reign in China coincided with the Little Ice Age, a global crisis. In response, scholars have published several reports in recent years addressing this topic. This paper presents a comprehensive overview of the current research findings in English regarding this subject and identifies existing research gaps. The author proposes that the impact of climate on different regions during the late Ming period remains largely underexplored. Furthermore, scholars must exercise caution when assuming that adverse climatic conditions uniformly impacted the Ming empire during the Little Ice Age. This paper also highlights the use of simplistic models by scholars linking cold and dry climates to crop failure, floods, droughts, population decline, and other factors. However, any straightforward models that presume causal determination risk ignoring historical facts. [ABSTRACT FROM AUTHOR]

Dynamic fluctuations in sea surface temperature within the North Atlantic Ocean (NA-SST) exert a pivotal influence on global climate change. Yet, the specific impacts of these variations on the temperature shifts within the Qinling-Bashan Mountains (QBM) of China, remain to be fully elucidated. Furthermore, a debate surrounding the manifestation of the Little Ice Age (LIA) within the QBM is ongoing, primarily due to the scarcity of reliable, long-term, and high-resolution temperature records. To bridge these knowledge gaps, in this paper, we present a ∼ 250-year temperature reconstruction (Tmax 11 – 7) developed based on a tree-ring-width chronology from the QBM. The new reconstruction not only aligns with a local winter temperature reconstruction based on historical document evidence, but also reveals robust regional and hemispheric temperature signals. Intriguingly, the study shows that the warming trend observed in the QBM since the Industrial Era is less pronounced than that witnessed across China and the Northern Hemisphere. The Tmax 11 – 7 reconstruction provides a glimpse into the final stages of the LIA, highlighting a relatively colder 19 th century followed by a warmer 20 th century. Notably, the warming trend post-1970s remains within the bounds of the 250-year temperature framework. The research further uncovers that NA-SST has predominantly governed the QBM's temperature fluctuations over the past centuries, as evidenced by the tight positive correlation between Atlantic multidecadal Oscillation (AMO)/Atlantic multidecadal variability (AMV) and Tmax 11 – 7. However, this dominant influence of NA-SST was temporarily subdued between 1900 and 1930 CE due to the interference of Pacific Decadal Oscillation (PDO). This finding serves as a reminder that future temperature projections for the QBM must account not only for the primary role of NA-SST but also the modulating effects of the PDO. The study is essential for shaping effective environmental management and adaptation strategies in the region. • A ∼ 250-year temperature reconstruction is developed using tree rings from the QBM. • The QBM saw the last stage of the LIA and recent warming is within historical frame. • North Atlantic SST (NA-SST) played a positive and dominant role on QBM'S temperature changes. • Weakened NA-SST's impact on temperature in 1900–1930 CE was due to PDO's interference. [ABSTRACT FROM AUTHOR]

In recent years, climate and environment changes since the Little Ice Age have become a focus in modern research. The paper selected the sediment (77 cm) of Sihu Lake, which was located in Guilin, southern China, as the research object and analyzed the karst wetland environmental changes within nearly 450 years. According to the vertical profile of indicators and geochemical elements in sediment core, the regional environmental evolution was divided into four stages. The former two stages were mainly influenced by Little Ice Age (1562–1895). The third stage climate has changed slowly. The fourth stage was mainly affected by human activities and global warming. The factor analysis of geochemical elements indicated that karst wetland regional environmental change was affected by four major factors. In the 53–77 cm stage (1562–1703), F1 (erosion factor), F2 (watershed runoff and diagenesis factor) and F3 (regional background factor) were reduced, indicating that it was in cold and dry stage of Little Ice Age. In the 20–53 cm stage (1703–1895), F1 and F2 increased, indicating that it was in cold and wet stage of Little Ice Age. In the 4–20 cm stage (1895–1987), F1, F2 and F4 (human activity factor) increased slowly, indicating that the climate was affected by global warming and more precipitation. In the 0–4 cm stage (1987–2007), F1 and F2 reduced and F4 increased, indicating the reduced precipitation, rising temperature and more impact of human activities. In addition, it was proposed that the Little Ice Age in Guilin District in southern China started in the 1560s and lasted until the 1895s or so. [ABSTRACT FROM AUTHOR]

This paper reports a study on reconstructing temperature series for ten regions of China over the last 1000 years with a time resolution of 10 a. The regions concerned are: Northeast, North, East, South China, Taiwan, Central, Southwest, Northwest China, Xinjiang and Qinghai-Tibet Plateau. A variety of proxy data, such as ice core, tree-rings, stalagmites, peat, lake sediments, pollen and historical records, were validated with instrumental observations made in the last 120 years, and applied in the reconstruction of the temperature series. A temperature series for whole China is then established by aver- aging the ten regional series with a weighting proportional to the area of each region. Finally, temperature variations for the last 1000 years are examined, with special focus placed on the characteristics of the Medieval Warm Period (MWP), the Little Ice Age (LIA), and Modern Warming (MW). [ABSTRACT FROM AUTHOR]

The driving force of climate change in the monsoon margin is complex, making it a key area for regional and global climate change research. Palaeohydrological studies in the monsoon margin have increased the resolution of research in the long term, transitioning from qualitative to quantitative studies to comprehend climate change processes, patterns, and mechanisms. Testate amoebae (TA) in peat sediments are used as a proxy indicator organism for quantitative reconstruction of palaeohydrology. Thus, their community changes are directly related to precipitation, and widely used to reconstruct the patterns of summer precipitation globally. We investigated TA species and reconstructed palaeohydrological changes in the Greater Khingan Mountains' Hongtu (HT) peatland, located in the East Asian Summer Monsoon (EASM) margin. The result showed that the most abundant TA species were Assulina muscorum (12.4 ± 5.0%) and Nebela tincta (8.9 ± 4.9%) in the HT peat core. The increase in dry indicator species (e.g., A. muscorum and Alabasta militaris) indicated a drying pattern in the HT peatland since 150 cal yr BP. Principal component analysis (PCA) explained 47.6% of the variation in the selected TA assemblages. During 400 to 250 cal yr BP, PCA axis 1 scores ranged from 0.2 to −1.3 (reflecting a drier climate), associating with the Little Ice Age. The paleohydrology of the northern part of the Greater Khingan Mountains was mainly controlled by the EASM, which was associated with changes in North Atlantic Sea surface temperature and solar radiative forcing. The apparent drying pattern may be the result of the gradual intensification of anthropogenic activities and the increase in EASM intensity. [ABSTRACT FROM AUTHOR]

Reconstruction and observational studies imply a potential linkage of moisture and precipitation change in arid central Asia and monsoonal East Asia, in which the evolution of moisture and precipitation in central Asia is out of phase with that in northern China but in phase with that in southern China. In order to ascertain whether there is a robust linkage between the changes in climate in Asian arid regions and monsoon regions and to elucidate the underlying dynamic mechanisms, we analyzed the Last Millennium Reanalysis dataset and outputs from the Community Earth System Model Last Millennium Ensemble (CESM-LME). The results indicate a significant decadal linkage between precipitation changes in central Asia's arid region and the Asian monsoon region during the last millennium, which is primarily driven by the Interdecadal Pacific Oscillation (IPO). In spring, the positive IPO could enhance westerlies over the Mediterranean Sea and to its east, which could transport more water vapor and cause increased precipitation over central Asia. In summer, the positive IPO is accompanied by a weakened Asian monsoon and southward Asian subtropical westerly jet, which can lead to increased (decreased) summer precipitation over southern China (over northern China and South Asia). The IPO plays a dominant role in connecting the decadal variations in precipitation between arid central Asia and monsoonal Asia by modulating the precipitation of their respective major rainy seasons. Model results suggest that this decadal linkage stems entirely from the internal variability present in the CESM-LME control and all single-forcing simulations. Changes in external forcing factors do not alter this inherent linkage caused by the IPO. Moreover, based on analyses of the aridity index and soil moisture content, this relationship of precipitation variation also causes a similar decadal linkage of moisture changes in central Asia and monsoonal Asia. The differences in the multi-centennial-scale moisture and precipitation variations in the Asian arid region and the monsoon region between the Medieval Climate Anomaly and Little Ice Age are also likely caused by IPO-like sea surface temperature anomalies. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of the Little Ice Age (LIA) on the Tibetan Plateau (TP) is of critical importance for understanding the climate changes over the past millennium. However, the data associated with the extents and chronologies of TP LIA moraines are highly dispersed in literature. Lack of systematic integration of these data hampers us to further understand the nature of the LIA, especially from a perspective of whole TP. The paper reviews multiple types of dating on LIA moraines to examine the timing and nature of the LIA on the TP. These include ages of radiocarbon 14C, lichenometry, and cosmogenic radionuclide (CRN), by which we can cross-date the same or morphostratigraphically similar landforms. LIA moraines on the TP are usually present a few hundred to thousand meters beyond the contemporary glaciers. The morphological and stratigraphic evidence indicates multiple periods of glacier advance during the last millennium (LIA). At present, available chronology evidence allows to fully compare the timing of the LIA maximum extents. The glaciers reached and retreated from their LIA maximum extents by an asynchronous pattern between different parts of the TP. The majority of glaciers advanced to their LIA maximum extents at late-14th and early-14th century on the southern and northwestern TP, respectively. The glaciers retreated from their LIA maximum extents during 16th to early-18th, late-14th to early-15th and early-16th century on the southern, northwestern, and northeastern TP, respectively. In addition, the glacier advance period of late-18th to early-19th centuries and retreat period of late-19th century are common on the whole TP. Comparison with ice core records suggests that on the TP, the glacier fluctuations responded more strongly to temperature than to precipitation. By comparison of the LIA chronologies from a global perspective, this paper also concludes that the LIA maximum extents occurred commonly earlier on the TP than in North Atlantic and Southern Hemisphere regions, despite of the variability in the timing of LIA maximum extents on the TP and in the North Atlantic regions. Further, more chronology programs, especially in the central TP, are necessarily needed to improve our understanding of the LIA glacier fluctuations. [Copyright &y& Elsevier]

This paper examines the topographic and geometric controls on glacier changes in area and equilibrium-line altitude (ELA) in the central Tien Shan, China, since the Little Ice Age (LIA). We delineate the extents of 487 modern glaciers and their corresponding maximum LIA glacial advances using satellite imagery in Google Earth, and analyze the relationships between the magnitude of glacier changes and a set of local topographic/geometric factors including glacier area, slope, aspect, shape, hypsometry and mean elevation. Our results show that: (1) glacier area decreased from 460.2km² during the LIA to 265.6km² in the 2000s (a loss of 42.3%), with an average ELA increase of ~100 m; (2) relative area changes of glaciers are strongly affected by two of these local factors (glacier area and mean elevation); and (3) ELA change does not show a strong relationship with local factors, suggesting that it may be controlled mainly by climatic factors. This study provides important insights into the local controls on glacier changes at the centennial timescale, which are of critical importance to assess future glacier changes in this arid and semi-arid region. [ABSTRACT FROM AUTHOR]

Research on the evolution and driving mechanisms of East Asian monsoon (EAM) precipitation during the past millennium has received considerable attention. Previous studies have focused on comparisons between relative mean dry/wet conditions and those linked to the Pacific sea surface temperature (SST) anomalies during the Medieval Warm Period (MWP) and the Little Ice Age (LIA); however, uncertainties remain regarding the relationship between precipitation changes and Pacific SST anomalies under sub-cool internal conditions within the LIA. Herein, we present a composite high-resolution monsoon precipitation record (from 1400 CE to the present) based on chroma and median grain size data from Lake Nvshan sediments in the Jiang-Huai (JH) region, central eastern China. The results indicate that more (less) precipitation in the JH region could be associated with the warm (cold) Pacific Decadal Oscillation (PDO) phase on inter-decadal scales. We also observed an enhanced modulating effect of the PDO on JH precipitation during the late LIA. These changes in the modulating effect were likely a response to enhanced PDO amplitudes induced by increased effective radiative forcing. [ABSTRACT FROM AUTHOR]

Climate change impacts ocean nutrient availability and will likely alter the marine food web. While climate models predict decreased average ocean productivity, the extent of these changes, especially in the marginal seas upon which large human populations depend, is not well understood. Here, we reconstructed changes in seawater phosphate concentration and nitrate source over the past 400 years, which reveals a more than 50% decline in residence time of seawater phosphate, and 8%–48% decline in subsurface nitrogen supply following the coldest period of Little Ice Age. Our data indicates a link between surface ocean nutrient supply and the East Asian Summer Monsoon strength in an economically important marginal sea. As climate models predict that the East Asian Summer monsoon will strengthen in the future, our study implies that surface ocean primary productivity may increase in the South China Sea, contrary to the predicted decrease in global average ocean productivity. Plain Language Summary: Global climate models predict that surface ocean nutrient concentrations will significantly decrease over the next 100 years as our climate changes. However, in the world's marginal seas, which human populations depend on most heavily for food security, the surface ocean biogeochemical changes are still difficult to predict with global‐scale models. Here, using coral‐based paleoclimate proxies, we reconstruct changes to surface phosphate concentration and to sources of surface nitrogen over the past four centuries in the South China Sea (SCS). Combined with box model simulations, our data reveal a more than 50% decline in phosphate residence time and an 8%–48% decline in subsurface nitrate supply from the 1600s to present. Such a decline implies a significant decrease in primary productivity and likely a community shift toward nitrogen‐fixing phytoplankton. Importantly, our data indicate that the decrease in nutrient supply was driven by weakened monsoon‐induced upwelling, demonstrating strong ties between nutrient supply and monsoon strength in the SCS. Climate change is predicted to strengthen the East Asian Summer Monsoon, and our results suggest that primary productivity in this economically important region may increase, contrary to the widely predicted decreases in average global ocean productivity. Key Points: Coral skeletal phosphorus content with scattered nitrogen isotopes is reconstructed over the past 400 yearsNutrient supply declined up to 48% since the Little Ice Age in the western South China SeaThe coral record from links nutrient supply to monsoon wind, implying higher productivity under a stronger monsoon in the future [ABSTRACT FROM AUTHOR]

Reconstructing three-dimensional palaeoglacier surface, thickness, and volume provides useful information for quantifying palaeo-climate conditions during glacial stages and assessing the impact of glacier change on water resources. A glacial flowline model has been implemented in Excel and ArcGIS to reconstruct palaeoglaciers based on digital elevation models and geomorphic constraints, such as moraines and trimlines that represent the margins and local heights of palaeoglaciers, respectively. However, significant efforts are still needed in using these tools for palaeoglacier reconstruction, such as digitizing flowlines, adjusting shear stress, and deriving shape factors. This paper presents an automated method, PalaeoIce, to reconstruct palaeoglaciers using geomorphic constraints. Coded in python, PalaeoIce is an ArcGIS toolbox with a set of tools to generate glacial flowlines, optimize shear stress, derive shape factors, calculate ice thickness values along flowlines, and interpolate palaeo ice surfaces based on geomorphic constraints. The use of PalaeoIce is demonstrated using extant glaciers with measured thickness values and moraines/trimlines of the Little Ice Age (LIA) and Marine Isotope Stage (MIS) 2 in the eastern Tian Shan, China. The reconstructed ice thickness values of Glacier No. 1 in this area show a reasonable agreement with field measurements with 1.4 % and 5.4 % differences between measured and reconstructed mean ice thickness values using the two methods included in PalaeoIce: a revised ice thickness model for extant glaciers and a palaeoglacier reconstruction method based on glacier outlines, respectively. Two approaches are then illustrated for palaeoglacier reconstructions using two sets of geomorphic constraints: one with the fully reconstructed glacier outlines during the LIA, and the other with just the terminal moraine and limited trimlines during MIS 2. PalaeoIce can significantly improve the efficiency of palaeoglacier reconstructions and the understanding of the impact of glacier change on water resources. • An automated method, PalaeoIce, is presented for palaeoglacier reconstruction. • Tools are developed to create flowlines, modify DEM, and reconstruct palaeoglaciers. • Reconstructed ice thickness data are validated by field measurements in Tian Shan. • Target geomorphic features are of importance for palaeoglacier reconstruction. [ABSTRACT FROM AUTHOR]

The Little Ice Age was concurrent with frequent natural disasters in China during the Ming and Qing Dynasties (1368–1911 AD). Using historical documents created in the Yangtze River Delta during these dynasties, we reconstructed the severity and frequency of locust plagues. We uncovered their temporal and spatial patterns, the relevant influencing factors, and the applied control measures. These locust plagues occurred in the Yangtze River Delta during summer and autumn and were considered moderate-degree disasters. The locust plagues during the Qing Dynasty were less harmful than those during the Ming Dynasty. The locust plagues occurred north of 31°N and were concentrated around lakes and rivers. Regarding long-term changes, three periods of frequent locust plagues were identified: 1520–1540 AD, 1610–1670 AD, and 1850–1870 AD. The locust plague cycles were dominated by long-term changes of 100 and 350 years, alternating with short-term changes of 10–30 years. Locust growth and development typically occur under suitable climate conditions. However, in the Yangtze River Delta, the relationship between locust outbreaks and temperature changes was insignificant, whereas flood disasters provided suitable humidity conditions for locust nymph growth. Locust plague outbreaks had a series of social impacts, one direct result was rising food prices. When facing locust plagues, the Ming and Qing Dynasties formed effective top-down preventative measures corresponding to local conditions. The locust plagues in the Yangtze River Delta during the Ming and Qing Dynasties occurred with regularity, were responsive to local hydrological conditions, and impacted social economies and technologies. [ABSTRACT FROM AUTHOR]

Climate change has become a serious issue, and tracing climate events from historical records could be a solution to find a way to deal with it. This study conducted two experiments for classifying metrological text data—one unsupervised method for exploring a solution in the lack of labeled data and another supervised method for achieving high-performance classification. Both experiments took the meteorological text records as material in the early Qing Dynasty (1644 C.E. to 1795 C.E.) from the REACHES database. We also integrated the classification results to develop a Spatio-Temporal research platform with an instant response front-end interface to help humanity researchers access and analyze data according to the three dimensions of time, area, and event categories. With our Spatio-Temporal research platform, we had the ability with ease to analyze the meteorological records during 1650 C.E. to 1700 C.E. the late stage of the Little Ice Age, to investigate the phenomenon of climate change in the Qing Dynasty of China. We will continue to expand the capacity of the database and establish a mature Spatio-Temporal research platform in the future. [ABSTRACT FROM AUTHOR]

The last millennium (LM, 1000–1850 AD) is crucial for studying historical climate change on decadal to multidecadal timescales. The summer surface air temperature (SAT) evolutions on regional scales (e.g. over China) are more uncertain than the globe/Northern Hemisphere, especially in response to external forcing factors and internal climate variability. Here, we provide one‐signal (full‐forcing) fingerprints of summer SAT in China derived from three large ensemble model archives with a multi‐proxy reconstruction during the LM, Little Ice Age (LIA, 1451–1850 AD), and Medieval Climate Anomaly (MCA, 1000–1250 AD), respectively. Our results show that (a) SATs in the northeast, southeast, northwest, and Tibetan Plateau (TP) regions of China show evident decreasing trends during the LM. External forcing response from all model archives agrees with the regional SAT reconstruction but underestimates variability in northwest China at the multidecadal timescale. (b) During the LIA, the summer regional SAT exhibits a cold condition in the reconstruction and simulations, especially in the northeast and northwest regions of China. External forcing responses in most model archives are the dominant factor on multidecadal SAT evolutions in the southeast, northeast, and TP regions of China and decadal SAT evolutions in northwest China. (c) During the MCA, detection and attribution of SAT shows that internal climate variability dominates in southeast, northeast, and TP regions of China, but external forcing dominates in northwest China at decadal to multidecadal timescales. These results contribute to a better understanding of the causes and mechanisms of regional climate change. [ABSTRACT FROM AUTHOR]

Instrumental records reveal that intense tropical cyclone (TC) activity varies with tropical sea surface temperature (SST) on annual-decadal scales. Drivers of intense TC activity at the centennial-millennial scale are less clear, due to the sparseness of pre-observational reconstructions. Here, we present a new 2 kyr continuous activity record of intense TCs from offshore eastern China. Our reconstruction indicates that this site witnessed enhanced TC activity during relatively warm periods, with a widespread increase in TC activity during the later part of the Little Ice Age. This latter observation reveals that enhanced TC activity was synchronized with increased Asian dust emissions during the Little Ice Age. TC activity was also lower in the late Roman Warm Period, when SST was higher but Asian dust emissions were lower than in the early phase. Such patterns suggest a centennial-millennial link between TC climatology and a combination of SST changes and Asian dust levels. Here, the authors show that enhanced tropical cyclone activity was synchronized with increased Asian dust emissions during the Little Ice Age, implying a mechanism linking tropical cyclone climatology to Asian dust levels, at 100 to 1000 year scales. [ABSTRACT FROM AUTHOR]

Understanding hydroclimatic patterns and their possible driving mechanisms during distinct climate periods over the last 1500 years—such as the Medieval Warm Period (MWP), the Little Ice Age (LIA), and the Current Warm Period—is crucial for predicting future changes to monsoon precipitation in southwest China under global warming scenarios. In this study, based on 210Pb and 137Cs dating of surface sediments and AMS 14C dating of terrestrial plant residues, we establish a robust age model that covers the last ∼1500 years (AD 439–2012) at Lake Yihai in southwest China. We use analyses of multiple geochemical proxy indices, including loss on ignition at 550°C, total organic carbon, total nitrogen, C/N ratios, and stable carbon isotopes of organic matter to reconstruct changes in summer monsoon precipitation at Lake Yihai during the last ∼1500 years. The results show that, over southwest China, warm and dry climate conditions prevailed during the MWP (AD 1000–1400) and the past 200 years, whereas conditions during the LIA (AD 1400–1800) were cold and wet. This is consistent with evidence from other geological records over southwest China, such as stalagmite and lake sediment data. Similar hydroclimatic patterns have occurred over the last 1500 years in adjacent tropical/subtropical monsoon regions where the climate is similarly dominated by the Indian summer monsoon (e.g., South China, the South China Sea, Southeast Asia, Northeast India). We suggest that the meridional migration of the mean position of the Inter-tropical Convergence Zone, and El Niño/Southern Oscillation conditions which are linked to tropical Pacific sea surface temperature, are responsible for centennial-scale hydroclimatic patterns over southwest China and adjacent areas during the last 1500 years. [ABSTRACT FROM AUTHOR]

It is conducive to the sustainable development of human beings in karst regions to research the mechanism of karst rocky desertification (KRD) expansion. Whether the large-scale KRD in southwestern China is caused by climate change or human activities is still controversial. In this study, the evolution of the KRD in southwestern China over the past 2000 years was reconstructed through the high-precision δ13C record of stalagmites from Shijiangjun (SJJ) Cave, Guizhou Province, China. The δ13C of the stalagmites from SJJ Cave exhibited heavy values from the Medieval Warm Period (MWP) to the Little Ice Age (LIA). Furthermore, the δ13C records of other stalagmites and tufa from southwestern China also showed the same significant heavy trend. Because the stalagmite δ13C could record the change of ecological environment, it indicated that the consistent change of the stalagmites δ13C may record the process of KRD expansion in the karst regions of southwestern China. During the MWP, the stronger Asian summer monsoon and the northward movement of the rain belt led to a dry period in southwestern China and a wet period in northern China. In contrast, it was wet in southwestern China and dry in northern China during the LIA. In addition, after the Jing-Kang event (JK event, AD1127) occurred at the end of the Northern Song dynasty, the political and economic center of China migrated to southern China for the first time, which changed the population distribution pattern of larger population in the north and smaller population in the south. Therefore, the expansion of KRD in southwestern China was exacerbated in the MWP due to the change of climate in southwestern China, the migration of a large number of people, wars, the large-scale reclamation of arable land, and the cultivation of large areas of crops. [ABSTRACT FROM AUTHOR]

In this study, simulations of 13 all‐forcing experiments from the Community Earth System Model Last Millennium Ensemble (CESM‐LME) archive were used to investigate the different spatiotemporal characteristics and corresponding mechanisms of the decadal megadroughts over the eastern China during two typical periods in the past millennium, that is, Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). The results show that there is no significant difference in either megadrought intensity or duration between the MCA and LIA, but there are significant differences in the megadrought frequencies. The frequency of megadroughts during the MCA is 1.44 times/hundred years, compared with 1.69 times/hundred years in LIA. Results from solar only sensitivity experiments and volcanic only sensitivity experiments show that this difference is mainly induced by the solar radiation. The mechanism analyses show that a spatial pattern of sea surface temperature anomalies (SSTA) resembling the positive Pacific Decadal Oscillation (PDO)‐like pattern have occurred simultaneously with the megadroughts during both the MCA and LIA. While, the megadroughts in MCA are strongly correlated with the strong PDO‐like SSTA patterns, and the megadroughts in LIA are strongly correlated with the weak PDO‐like SSTA patterns. In addition, the anomalous sea level pressure (SLP) field and wind field associate with the megadroughts during the MCA and LIA are consistent with the strengths of SSTA, with significant larger SLP and wind anomalies during the MCA than those during the LIA. Therefore, it can be concluded that the responses of the large‐scale atmospheric circulation patterns to SSTA are similar during these two typical periods, and the difference in the megadrought frequencies is due to the nonlinear response of the precipitation variability to the large‐scale atmospheric circulation patterns. [ABSTRACT FROM AUTHOR]

Instrumental data indicate the occurrence of a dipolar pattern of precipitation anomalies between north China and the Yangtze River Valley (YRV), which was termed "northern drought (flood)—southern flood (drought)" scenario. It has been shown that this pattern occurred during the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). However, there are questions about whether this dipolar pattern also occurred during the entire Holocene, and the mechanism responsible. Addressing these questions is of fundamental importance for understanding the spatiotemporal evolution of precipitation in East Asian summer monsoon region. Numerous studies of north China have demonstrated that the mid‐Holocene was humid, and the early and late Holocene were dry. However, there are relatively few equivalent studies in the YRV. To this end, we conducted detailed geochemical analysis of an AMS 14C‐dated sediment core from Lake Nanyi in the YRV. Our results indicate humid periods at Lake Nanyi occurred during 11.5–8.0 ka and from 2.0 ka to the present, while dry conditions occurred during ~8.0–2.0 ka. These results, together with published records from Dajiuhu peatland and Heshang Cave, collectively indicate in the YRV, the mid‐Holocene (~8.0–3.0 ka) was dry, while the early and late Holocene were humid, which is the inverse of the pattern in north China. Thus, we conclude there was an asynchronous evolution of hydroclimatic changes between north China and the YRV during the Holocene. We interpret this dipolar pattern as the result of ENSO variations: in a La Niña‐like state, the Western Pacific Subtropical High retreated northeastward, which would enable the rainfall belt to move northward and result in increased (decreased) precipitation in north China (the YRV). Sea surface temperature records from the Pacific Ocean and model simulations support this mechanism: a La Niña‐like state in the mid‐Holocene resulted in more (less) precipitation in north China (the YRV). [ABSTRACT FROM AUTHOR]

Catastrophic events often interrupt long‐term Earth surface processes. In coastal areas, although millennial‐scale trends of climatic and sea‐level changes determine the trajectory of sedimentary landform evolution, storm and/or tsunami activity can cause abrupt changes in depositional conditions that may alter the long‐term sedimentary processes. Here, we report a sedimentary hiatus that is widely observed from the late Holocene sedimentary sequence at the seabed along the southeast China coast. This hiatus was discovered by close temporal sedimentary and radiocarbon dating analyses of a seabed sedimentary sequence in the mouth area of the Pearl River estuary. The results suggest that a couple of metres in the middle to late Holocene sediment at the seabed were eroded by a catastrophic event happening c. 1000–800 cal. Years BP. In theory, a mega‐tsunami generated from the Manila Trench could have caused such erosion at the seabed, but there is a lack of direct geological and historical evidence to support such a hypothesis. Much more likely, a super‐typhoon struck the coast and caused the erosion. This hypothesis is strongly supported by the region's historical and geological records, which suggest a period characteristic of intense typhoons ranging from the Medieval Warm Period to the climate transition phase (c. 1000–600 cal. Years BP). During the subsequent Little Ice Age, deposition of sandy sediment continued, suggesting frequent but weaker typhoon activity. Over the past two centuries the deposition of sandy sediment and gravels began, implying the beginning of a phase of intensifying typhoon conditions, possibly a result of the recent warming climate. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Private diaries are important sources of historical data for research on climate change. Their advantages include a high veracity and reliability, accurate time and location information, a high temporal resolution, seasonal integrity, and rich content. In particular, these data are suitable for reconstructing short-term, high-resolution climate series and extreme climatic events. Through a case study of Yunshan Diary , authored by Bi Guo of the Yuan dynasty of China, this article demonstrates how to delve into climate information in diaries, including species distribution records, phenological records, daily weather descriptions and personal experiences of meteorological conditions. In addition, this article considers how to use these records, supplemented by other data, to reconstruct climate change and extreme climatic events on various timescales, from multidecadal to annual or daily. The study of Yunshan Diary finds that there was a relatively low amount of precipitation in central and southern Jiangsu Province in the summer of 1309; the winter of 1308–1309 was abnormally cold in the Taihu Lake basin. In the early 14th century at the latest, the climate in eastern China had begun to turn cold, which reflects the transition from the Medieval Warm Period to the Little Ice Age. [ABSTRACT FROM AUTHOR]

During the latter stages of the Holocene, and prior to anthropogenic global warming, the Earth underwent a period of cooling called the neoglacial. The neoglacial is associated with declining summer insolation and changes to Earth's surface albedo. Although impacts varied globally, in China the neoglacial was generally associated with a cooler climate and an attenuated Asian summer monsoon. Few studies in central China, however, have explored the impact of neoglacial cooling on freshwater diversity, especially in alpine regions. Here we take a palaeolimnological approach to characterise multi-decadal variability in diatom community composition, ecological guilds, and compositional turnover over the past 3500 years from the alpine Yuhuang Chi lake on Mount Taibai in the Qinling mountains. Diatoms in the high-profile guild dominate much of the record from 3500 to 615 calBP , which suggests that few nutrients in the lake were limiting overall, and disturbance and herbivory were likely low. After 615 calBP , low-profile and planktic guild diatoms increase, suggesting greater turbulence in the lake, alongside a decline in available nutrients. Diatom turnover highlights periods in the lake history when deterministic processes structured diatom communities. For example, an abrupt decline in turnover is coincident with the shift from high- to low-profile diatoms at 615 calBP , and this is likely due to the onset of the Little Ice Age in the region. We suggest that Yuhuang Chi lake became more shallow during peak regional aridity, which led to the short-lived community restructuring observed in the record. [ABSTRACT FROM AUTHOR]

Variations of precipitation, also called the Meiyu rain, in the East Asian summer monsoon (EASM) domain during the last millennium could help enlighten the hydrological response to future global warming. Here we present a precisely dated and highly resolved stalagmite δ18O record from the Yongxing Cave, central China. Our new record, combined with a previously published one from the same cave, indicates that the Meiyu rain has changed dramatically in association with the global temperature change. In particular, our record shows that the Meiyu rain was weakened during the Medieval Climate Anomaly (MCA) but intensified during the Little Ice Age (LIA). During the Current Warm Period (CWP), our record indicates a similar weakening of the Meiyu rain. Furthermore, during the MCA and CWP, our records show that the atmospheric precipitation is similarly wet in northern China and similarly dry in central China, but relatively wet during the CWP in southern China. This spatial discrepancy indicates a complicated localized response of the regional precipitation to the anthropogenic forcing. The weakened (intensified) Meiyu rain during the MCA (LIA) matches well with the warm (cold) phases of Northern Hemisphere surface air temperature. This Meiyu rain pattern also corresponds well to the climatic conditions over the tropical Indo-Pacific warm pool. On the other hand, our record shows a strong association with the North Atlantic climate as well. The reduced (increased) Meiyu rain correlates well with positive (negative) phases of the North Atlantic Oscillation. In addition, our record links well to the strong (weak) Atlantic meridional overturning circulation during the MCA (LIA) period. All abovementioned localized correspondences and remote teleconnections on decadal to centennial timescales indicate that the Meiyu rain was coupled closely with oceanic processes in the tropical Pacific and North Atlantic oceans during the MCA and LIA. [ABSTRACT FROM AUTHOR]

Severe El Niño-Southern Oscillation (ENSO) droughts that occurred in southwest China during the last millennium have exerted important impacts on natural ecosystems and human society. Fossil phytoliths in high-resolution (~ 7 year) fluvial sediments in the monsoon rainforest are studied to reveal the influence of ENSO activity on tropical southwest China. The phytolith records together with multiproxy analysis indicate that three phases of distinctively warm-dry and cool-wet climate pattern have exerted profound influences on the sedimentary environment and tropical monsoon rainforest, which is sensitive to the occurrences of severe droughts and fires. Integrated comparisons demonstrate that climatic variations rebuilt by Ic (temperature proxy) are consistent with the temperature change in the Northern Hemisphere, Indian Summer Monsoon (ISM) variations in the northern Indian Ocean and southwest China, and aridity index (Iph) is linked to ENSO activity in the equatorial Pacific Ocean. At decadal timescale, there is an internal connection between ISM variability and ENSO activity in the tropical southwest China. Due to the modulation of ENSO activity, there is an antiphase relationship between temperature and ISM intensity, with a remarkably dry Medieval Warm Period (MWP), Modern Warming (MW) and a mostly wet Little Ice Age (LIA) during the last millennium. Spectral analysis of the climatic indices (Ic and Iph) indicated that the dominant cycle (~ 88 year) is a significant component of periodic solar activity variations. Our results confirmed that the possible forcing mechanism of such a "warm-dry and cool-wet" climate pattern is related to the coupling of solar periodic variations and ENSO variance spanning the tropical Indian Ocean and the "Indian subcontinent-southwest China". This is significant of understanding the relationship among droughts, ENSO variance and ISM variation in the tropical southwest China under the background of global warming. [ABSTRACT FROM AUTHOR]

The formation and evolution of permafrost in China during the last 20 ka were reconstructed on the basis of large amount of paleo-permafrost remains and paleo-periglacial evidence, as well as paleo-glacial landforms, paleo-flora and paleofauna records. The results indicate that, during the local Last Glacial Maximum (LLGM) or local Last Permafrost Maximum (LLPMax), the extent of permafrost of China reached 5.3×106−5.4×106 km2, or thrice that of today, but permafrost shrank to only 0.80×106−0.85×106 km2, or 50% that of present, during the local Holocene Megathermal Period (LHMP), or the local Last Permafrost Minimum (LLPMin). On the basis of the dating of periglacial remains and their distributive features, the extent of permafrost in China was delineated for the two periods of LLGM (LLPMax) and LHMP (LLPMin), and the evolution of permafrost in China was divided into seven periods as follows: (1) LLGM in Late Pleistocene (ca. 20000 to 13000−10800 a BP) with extensive evidence for the presence of intensive ice-wedge expansion for outlining its LLPMax extent; (2) A period of dramatically changing climate during the early Holocene (10800 to 8500−7000 a BP) when permafrost remained relatively stable but with a general trend of shrinking areal extent; (3) The LHMP in the Mid-Holocene (8500−7000 to 4000−3000 a BP) when permafrost degraded intensively and extensively, and shrank to the LLPMin; (4) Neoglaciation during the late Holocene (4000−3000 to 1000 a BP, when permafrost again expanded; (5) Medieval Warming Period (MWP) in the late Holocene (1000−500 a BP) when permafrost was in a relative decline; (6) Little Ice Age (LIA) in the late Holocene (500−100 a BP), when permafrost relatively expanded, and; (7) Recent warming (during the 20th century), when permafrost continuously degraded and still is degrading. The paleo-climate, geography and paleopermafrost extents and other features were reconstructed for each of these seven periods. [ABSTRACT FROM AUTHOR]

The history of coastal catastrophic floods was reconstructed for the first time using the geochemical proxy in shelf sediments. The reconstruction is based on the identification of sediment layers accumulated on the shelf during the intensive discharge of the river runoff suspended matter from the land which does not contain bromine. The set of isotopic (AMS 14C, 210Pb, 137Cs), tephrastratigraphic, and paleomagnetic methods was used for the detailed chronology of sediments. The scanning of chemical composition of sediments with the step of 0.5–0.8 mm is performed using the synchrotron radiation X-ray fluorescence in the VEPP-3 storage of the Institute of Nuclear Physics of Siberian Branch of Russian Academy of Sciences. The history of catastrophic floods for the past 1800 years is reconstructed based on the typical variations in bromine concentration in one of the cores from the Amur Bay (the Sea of Japan). New methodological approaches to the flood signal extraction are proposed. The revealed inverse correlation between the frequency of floods caused by typhoons over the coast of the Sea of Japan and southern China agrees with the existing assumption on the change in their trajectories in different periods of global climate change. [ABSTRACT FROM AUTHOR]

The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer (CF-IRMS). Because of predictable oxygen isotopic fractionation between cellulose and its source water, the oxygen isotopic composition of paleo-lake water has been established quantitatively. Combined oxygen isotopic values of cellulose and carbonates were used in the 'Craig' equation to determine paleotemperatures and their variation in the lake during the past 500 years. Results show that the paleotemperature trend correlates well with meteorological records from Weining. There are four notable cold intervals at Lake Caohai over the past 500 years, namely 1540-1570AD, 1670-1715AD, 1780-1870AD and 1900-1930AD, and the former three cold intervals have been observed in the conventional Little Ice Age (LIA). These cold periods at Lake Caohai correspond well with those recorded from tree ring, peat, and ice core data from adjacent regions, particularly temperature those inferred from δO of peat cellulose from Hongyuan Southwestern China. The trend in paleotemperature variations at Lake Caohai are also consistent with both the change of Indian summer monsoon, derived from δO values of a stalagmite in Dongge, and a recorded shift in solar activity. The findings of this study illustrate that coupled analysis of δO values of cellulose and carbonates from lake sediments may be used as a paleotemperature proxy. These results also provide further evidence of the existence of LIA in southwestern China. [ABSTRACT FROM AUTHOR]

Historical case studies of climate change impacts and the resulting social responses can provide analogies for better understanding the impacts of current and future climate changes. Around the turn of the 19th century, the climate of the North China Plain experienced a shift from a relatively warm stage in the 18th century to a colder stage in the 19th century, which was characterised by a much colder climate and more frequent and severe floods and droughts. Historical information about refugees, social disorder, grain transportation, and disaster relief on the North China Plain in 1780-1819 is collected from the Veritable Records of the Qing Dynasty (a collection of official records). The mechanism of climate change affecting the food security of the society, as indicated by the development of a refugee problem around the turn of the 19th century, is analyzed by examining the social vulnerability. There are four basic findings: (1) In the 40 years from 1780-1819, the society on the North China Plain was unstable and characterised by a significant deterioration of the refugee situation. The number of refugees increased markedly, and their behaviour became increasingly violent. In the 1780s, most of the disaster victims chose to stay at their residences waiting for relief. From 1790 to 1800, hundreds of thousands of refugees migrated to northeast China. In the 1810s, the frequency of farmer rebellions increased sharply. (2) The increase in instability corresponded to the climatic cooling over the same time period. The increased instability was a result of the negative impacts of climate change accumulating and transmitting to the social level. (3) For food security, a precondition for the negative impacts of climate change on human society was the vulnerability of the regional socioeconomic system, which had a high sensitivity and low capacity to respond. This vulnerability could be described by the following three observations: ① The regional balance of supply and demand for food was in a critical state, which led to a high sensitivity and dramatic reduction in yield that was caused by climate change; ② the capacity for disaster relief efforts by the government was too low to meet the needs of crisis management; ③ the capacity for refugees' resettlement in eastern Inner Mongolia and northeast China, which both border the North China Plain, was severely restricted by climatic conditions or the quarantine policy. (4) It is estimated that climate change caused the social vulnerability to reach a critical level approximately 20 years earlier on the North China Plain. [ABSTRACT FROM AUTHOR]