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Reconstruction of historical cropland cover is not only essential for studying agricultural development in historical periods, but also provides the basic data for long-term global and climatic change simulations. However, reconstructing the amount and spatial distribution of cropland prior to the past millennium remains challenging because of incomplete data and the suitability of the allocation method. Based on the household census and cropland demand per household data, which was calculated from grain consumption per household and crop yield per unit area, this study estimated the prefecture-level cropland area in northern China in AD 609 during the Sui dynasty. Then, a cropland allocation model based on natural land suitability for cultivation was used to reconstruct the spatial distribution of cropland in 5′ × 5′ grid cells. The results were as follows: (1) the cropland area in northern China in AD 609 was 1.77 × 105 km2, with an average cropland area fraction of 10.04%. (2) The cropland was continuously distributed in the North China Plain, Guanzhong Plain, Fenhe Valley and central Shangdang and Changping on the Loess Plateau, resulting in a high cropland agglomeration area appearing in those regions. While it is scattered in the northern Loess Plateau and the Hexi Corridor. (3) Compared with our reconstruction, the HYDE dataset underestimated the cropland area in plains except for riverine areas and overestimated the cropland area in the hills and mountainous areas along the border. (4) This discrepancy was primarily derived from population differences and the divergent cropland allocation methods between the two datasets.

The natural vegetation has been substantially changed over the last millenium, especially from forest to agricultural areas in Europe. To study the effects of deforestation on carbon and climate system, it is essential to construct spatially precise maps in forest cover. The current representative historical forest data sets are either derivatives of agricultural datasets or are produced based on the deforestation-population relationship. Almost no attempts have been made to use the inherently linked relationship between deforestation and cropland expansion that has run through Europe for millennia. This study created an approach based on the relationship between cultivation intensity and forest fraction to reconstruct forest cover changes in central and southeast Europe from AD 1800 to 2000 by the following steps: (1) To develop the spatial relationship curve (spatial resolution is 1°) between the “cultivation intensity (0–100%)” and the “forest fraction (0–100%)” derived from modern land cover datasets; (2) To generate the national-scale cropland data based on historical records from AD 1800 to 2000, and to allocate them to a 1° pixel; (3) To reconstruct the forest cover using the aforementioned relationship curve and the historical gridded cropland database. The results show that: (1) The forest fraction in central and southeast Europe decreased from 38.4% in AD 1800 to 27.0% in AD 1900, and then increased to 32.5% in AD 2000. (2) In AD 1800, large areas of forests can be primarily found in Luxembourg, Netherlands and Belgium, the south of France, the south of Germany, the Alps region, Poland, and the majority of the Balkans. (3) Throughout the 19th century, the entire region was generally subjected to deforestation, with large areas of forest coverage only being preserved in the Alps and the western and southern Balkans after 100 years of exploration. (4) The forest coverage in most of the study regions increased again at the end of the 20th century.

Climate change affects relationships between regions. The sequence of peacemaking events between farming and nomadic groups in northern China from the Western Han to the Qing dynasty was constructed based on historical documents. We analyzed the impacts of climate change on ethnic relationships using war and temperature sequence data from previous studies. The main results are as follows: 1) There were 504 peacemaking events between farming and nomadic groups, with an average frequency of 2.4 times per decade. Paying tribute (68.9%) occurred significantly more frequently than intermarriage for pacification (31.1%). The sequences showed different stages. 2) There were more peacemaking events during cold periods and fewer during warm periods. Intermarriage for pacification played a greater role in peacemaking during warm periods, while paying tribute was more important during cold periods. 3) High-incidence stages of war and of peacemaking events alternated. Peacemaking events occurred more frequently during cold periods and wars occurred more frequently during warm periods. 4) During warm periods, farming and nomadic groups had enough power to contend with each other, wars occurred frequently, and intermarriage was often used for peacemaking. During cold periods, agriculture and animal husbandry declined, both sides weakened, and the power difference between them usually increased. Wars rarely occurred, and paying tribute was often used for peacemaking. Ethnic relationships are affected by many factors. As a background factor influencing land productivity, climate indirectly affected conflict-resolution measures between farming and nomadic groups. We can hereby consider ways to manage interregional ethnic relationships under global climate change today.

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.

To improve the accuracy of historical cropland data, we reconstructed cropland cover in the northern China’s farming–pastoral zone during the Liao dynasty using historical literature and settlement relics. We first reconstructed the total cropland area using historical household data based on the cropland area per household. Next, we allocated the cropland area into 5′ grid cells weighted by settlement density to generate a cropland data. Our main findings were as follows: (1) Data on settlement relics enabled not only the identification of ancient farming areas but also the allocation of cropland cover within high resolution grids in the study area. (2) In the flourishing period of the Liao dynasty, the total cropland area was 0.39 × 104 km2. The cropland grids comprised 28.30% of the total grids, with average and maximum values of cropland fractions of 6.61% and 31.18%, respectively. (3) Compared with our result, we found that the PJ overestimate the cropland area of the study area in 1100 AD, whereas the HYDE 3.2 underestimate it. The area of anthropogenic land use in KK 10 was larger than the cropland area in this study too. None of the three global datasets revealed the mosaic spatial distribution pattern of cropland cover in this study area. (4) The orders of land suitability for cultivation during the Liao dynasty and the present period were almost the identical, even in the farming–pastoral zone of northern China, which has fragile ecological environment.

To evaluate the climatic and ecological impacts of anthropogenic activities in global change research, it is essential to reconstruct historical land use and land cover change on regional and global scales. In this study, we reconstructed cropland areas for 54 provinces within the European part of Tsarist Russia (ETR) over the periods of 1696–1914 using historical data, including cropland area, population, grain consumption, and grain yield per unit area. The main results are as follows. (1) Total cropland areas and fractional cropland areas of ETR for 8 time sections during 1696–1914 were reconstructed, the former increased from 31.98×104 km2 to 147.40×104 km2, and the latter increased from 7.89% to 29.20%. The per capita cropland area decreased from 0.0246 km2 to 0.0113 km2 during 1696–1914. (2) Cropland expanded from the central and southwestern ETR to the black soil region, surrounding area of the Volga River, Ukraine region, the new Russia region, the vicinity of Ural, and north Caucasus region. (3) The expansion of territory, increase and migration of population, policies related to agricultural development and foreign trade, and the impacts of climate change were the reasons for the changes in cropland within ETR from 1696 to 1914. (4) In 1914, the cropland area and fractional cropland area of each province varied from 0.16×104 km2 and 0.76% to 5.65×104 km2 and 76.68%, respectively. (5) The comparisons show that the cropland areas of ETR in this study for 1696–1914 are higher than those in the HYDE 3.2 dataset. The main reason for this finding might be the underestimation of per capita cropland areas in the HYDE 3.2 dataset, which values remained at approximately 0.01 km2 from 1700 to 1920.

Land use-induced land cover change (LUCC) is an important anthropogenic driving force of global change that has influenced, and is still influencing, many aspects of regional and global environments. Accurate historical global land use/cover datasets are essential for a better understanding of the impacts of LUCC on global change. However, there are not only evident inconsistencies in current historical global land use/cover datasets, but inaccuracies in the data in these global dataset revealed by historical record-based reconstructed regional data throughout the world. A focus in historical LUCC and global change research relates to how the accuracy of historical global land cover datasets can be improved. A methodology for assessing the credibility of existing historical global land cover datasets that addresses temporal as well as spatial changes in the amount and distribution of land cover is therefore needed. Theoretically, the credibility of a global land cover dataset could be assessed by comparing similarities or differences in the data according to actual land cover data (the “true value”). However, it is extremely difficult to obtain historical evidence for assessing the credibility of historical global land cover datasets, which cannot be verified through field sampling like contemporary global land cover datasets. We proposed a methodological framework for assessing the credibility of global land cover datasets. Considering the types and characteristics of the available evidence used for assessments, we outlined four methodological approaches: (1) accuracy assessment based on regional quantitative reconstructed land cover data, (2) rationality assessment based on regional historical facts, (3) rationality assessment based on expertise, and (4) likelihood assessment based on the consistency of multiple datasets. These methods were illustrated through five case studies of credibility assessments of historical cropland cover data. This framework can also be applied in assessments of other land cover types, such as forest and grassland.

The Dongting Plain is an area characterized by wetland losses because of long-term polder construction. The study of historical polder expansion provides an opportunity to better understand the loss of wetlands covered by polders. To reconstruct the polder expansion over time, the polder patches extracted though remote sensing were marked with the names obtained from maps and the times of construction obtained from local gazetteers, and shown in the chronological order of turning points. Then, the distribution and changes in the wetlands covered by polders during 1368–1980 were reconstructed. The following are the major findings: (1) the current polders (2010s) accumulated over many centuries. There were 5.7% of the current polder area in 1644, 14.0% in 1735, 23.4% in 1850, 55.0% in 1911, 73.6% in 1949, and 100% in 1980; (2) the wetlands were mostly lost in the northern part of the region and declined rapidly over the past two centuries. The wetland area in 1850 was 6635 km2, which in 1911, 1949 and 1980 were 73.9%, 62.7% and 40.6% of that in 1850, respectively; (3) there were differences in the rate of wetland loss. The fastest time of wetland area disappearance was in 1949–1980, and 45.8 km2 of the wetlands had been lost each year; and (4) there was a spatial difference in wetland losses caused by polder expansion. In the northern part of the area, the wetland loss was mainly in 1851–1980, and the polders constructed in this period covered 89.5% of the polder area. In contrast, in the southern part of the area, the change in the wetland area was relatively small in each period, and the polder constructed before and after 1850 covered 48.3% and 52.7% of the polder area, respectively.

ENSO is an interannual mode which may be affected by external forcing, such as volcanic eruptions. Based on the reconstructed volcanic eruptions chronology and ENSO sequences, both 195 large volcanic eruptions (VEI≥4) and 398 ENSO (El Nino and La Nina) events were extracted from 1525 to 2000. An analysis of the correspondence between the large volcanic eruptions and ENSO events was performed by matching the large volcanic eruptions with the types and magnitudes of ENSO events present in the 0–2 years after the eruptions. The results show the following: (1) The percentages of ENSO events within the 3 years after the large eruptions had increased to 68.3% from 31.7% compared with those with no-eruptions in the previous 0–2 years. In addition, the ratio of El Nino to La Nina events turned from 2:3 to 1:1, and more El Nino events occurred in the 0 year after eruptions in the low-latitudes of the Northern Hemisphere and in the tropics but more La Nina events occurred in the 0 year after in the high-latitudes of the Northern Hemisphere and the Southern Hemisphere. (2) After the eruptions, the weak (W) El Nino events had increased by 8 percentage points and the very strong (VS) El Nino events had decreased by 10 percentage points; conversely, there was a decrease by 15 percentage points of the weak La Nina events and an increase by 11.4 percentage points of the very strong La Nina events. Specifically, the percentages of strong La Nina events increased to a peak at 1 (+1) year after the eruptions. (3) The percentage of eruptions followed by single-year ENSO was the greatest. The percentage of ENSO events that occurred in the consecutive 2 years following an eruption was approximately equal to the percentage of events that occurred consecutively 3 years following an eruption, and both sets of ENSO magnitudes showed a decreasing trend.

Global historical cropland datasets allocate cropland areas into grids above on the assumption that land suitable for crops is similar to that in the present or changeless over time. However, land suitability has changed over time. The Dongting Plain, which is full of polders, is characterized by changing land suitability for crops over the past 300 years and provides a case study of the impact of changing land suitability on spatially explicit reconstructions. Here, cropland areas were reconstructed at the county level and allocated into grids at 0.5′ × 0.5′. This allocation was based on the expansion of polders, which indicated land suitable for crops. The results showed the following: (1) The land suitable for crops constituted 68.24% of the total area in 1750 and it expanded after 1850, which in 1911, 1949, and 1985 was 1.10, 1.18, and 1.25 times that of 1750, respectively. (2) The regional cropland area fraction was 21.60% in 1750 and it increased after 1850, which in 1911, 1949, and 1985 was 127.21%, 140.27%, and 156.03% that of 1750. (3) The grids with cropland fractions increased due to polder development by more than 30% in the middle of the region from 1750 to 1985, occupying 32.16% of the total grids. (4) Changes in the land suitability for crops impacted the spatially explicit reconstruction. The grids unsuitable for crops were 78, 46, and 28 in 1850, 1911, and 1949 at 0.5′ × 0.5′, which constituted 19.21%, 11.33%, and 6.90% of the total grids, respectively. In comparison with this study, some of the grids unsuitable for crops were allocated as cropland by HYDE 3.2 and covered 93.59%, 89.13%, and 82.14% of the total unsuitable girds.

Phenological records in historical documents have been proven to be of unique value for reconstructing past climate changes. As a literary genre, poetry reached its peak in the Tang and Song dynasties (618–1279 CE) in China. Sources from this period could provide abundant phenological records in the absence of phenological observations. However, the reliability of phenological records from poems, as well as their processing methods, remains to be comprehensively summarized and discussed. In this paper, after introducing the certainties and uncertainties of phenological information in poems, the key processing steps and methods for deriving phenological records from poems and using them in past climate change studies are discussed: (1) two principles, namely the principle of conservatism and the principle of personal experience, should be followed to reduce uncertainties; (2) the phenological records in poems need to be filtered according to the types of poems, background information, rhetorical devices, spatial representations, and human influence; (3) animals and plants are identified at the species level according to their modern distributions and the sequences of different phenophases; (4) phenophases in poems are identified on the basis of modern observation criteria; (5) the dates and sites for the phenophases in poems are confirmed from background information and related studies. As a case study, 86 phenological records from poems of the Tang Dynasty in the Guanzhong region in China were extracted to reconstruct annual temperature anomalies in specific years in the period between 600 and 900 CE. Following this, the reconstruction from poems was compared with relevant reconstructions in published studies to demonstrate the validity and reliability of phenological records from poems in studies of past climate changes. This paper reveals that the phenological records from poems could be useful evidence of past climate changes after being scientifically processed. This could provide an important reference for future studies in this domain, in both principle and methodology, pursuant of extracting and applying phenological records from poems for larger areas and different periods in Chinese history.

Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes. Substrate temperature and pressure of helium atmosphere were optimized for the production of the carbon nanomaterials. The samples were modified or destroyed with different methods to mimic typical environments responsible of severe surface degradation. The emulated conditions were performed by four surface treatments, namely thermal oxidation, substrate overheating, exposition to glow discharge, and metal coating due to arc plasma. In the next step, the samples were regenerated on the same substrates with identical deposition technique. Damaging and re-growth of GPN samples were systematically characterized by scanning electron microscopy and Raman spectroscopy. The full regeneration of the structural and morphological properties of the samples has proven that this healing method by arc plasma is adequate for restoring the functionality of 2D nanostructures exposed to harsh environments.

Case studies on the impacts of extreme weather events at different spatial and temporal resolutions can help further the understanding of the impacts of climate change and serve as references for coping with future climate change challenges as well. We reconstructed the monthly time series data on social impacts of an extreme drought event in the Guanzhong area, Shaanxi Province, China, using newspaper records from 1928 to 1931. Changes in food substitutions, food prices, social unrest, and social resilience are analyzed to show how the drought affected the area. The results show that (1) the evolution of social impacts of the drought can be divided into five stages, and the variation in the impact magnitude is strongly influenced by the summer and autumn harvests; (2) the cumulative effects of the persistent drought are observed, and the level of social resilience declined rapidly and nonlinearly; and (3) there are two kinds of spreading patterns of drought’s impacts across natural, supporting, and humanity systems: hierarchical propagation and cascading effects. They act over different spatial and/or temporal scales and could provide the inspiration for the strategies designed to mitigate the impacts of climate change and extreme weather events today.

Historical land cover data are the basis of quantifying the environmental effects of land use and land cover change (LUCC), and a lower deviation is expected when they are used to study the carbon cycle and create climate simulations. Generally, a global scenario of past LUCC that can be supported by relevant historical evidence is more likely to describe the actual LUCC pattern of a given region. Starting from this point, we selected qualitative and quantitative evidence of cropland cover changes in Germany over the last millennium to explore the feasibility of using historical information to discuss the deviation of global LUCC scenarios in regions lacking independent reconstructions. A comparison between the cropland data of HYDE 3.2.1, a representative and widely used global historical land use scenario, and German historical evidence was conducted. The total areas of croplands in HYDE showed high consistency with previous studies based on region-specific sources, although HYDE’s interpolation method after 1700 AD may need some improvement. Several deviations arise from cropland allocations in HYDE 3.2.1, especially for the early cropland expansion in areas along major rivers and wetlands. HYDE’s insufficient consideration of the spatial variation in population over time might account for the noticeable discrepancies between the spatial patterns of HYDE croplands and medieval settlements, as well as research on the agricultural landscape from 1000 AD to 1400 AD. The findings of this study suggest that the introduction of human indicators such as settlement data could help to improve the estimation and allocation algorithms of global-scale LUCC reconstructions.

Phenological records in historical documents have been proved to be of unique value for reconstructing past climate changes. As a literary genre, poetry reached its peak period in the Tang and Song Dynasties (618–1260 AD) in China, which could provide abundant phenological records in this period when lacking phenological observations. However, the reliability of phenological records from poems as well as their processing methods remains to be comprehensively summarized and discussed. In this paper, after introducing the certainties and uncertainties of phenological information in poems, the key processing steps and methods for deriving phenological records from poems and using them in past climate change studies were discussed: (1) two principles namely the principle of conservative and the principle of personal experience should be followed to reduce the uncertainties; (2) the phenological records in poems need to be filtered according to the types of poems, the background information, the rhetorical devices and the spatial representations; (3) the animals and plants are identified to species level according to their modern distributions and the sequences of different phenophases; (4) the phenophases in poems are identified on the basis of modern observation criterion; (5) the dates and sites for the phenophases in poems are confirmed from background information and related studies. Finally, the temperature anomalies reconstructed by phenological records from poems were compared with those reconstructed by other historical documents in published studies to demonstrate the validity and reliability of phenological records from poems in studies of past climate changes. This paper proved that the phenological records from poems could be useful evidence of past climate changes after being scientifically processed and also provides a reference in both principle and methodology for the extraction and application of phenological records from poems.

The North China Famine of 1876&ndash, 1879, known in Chinese as the Dingwu qihuang (丁戊奇荒), is a famous case of drought-induced famine in Chinese history. The purpose of this paper is to provide empirical and historical evidence for understanding the impacts of extreme climate events and major disasters and the mechanisms of adaptation. From the aspects of famine-related migration and the allocation of relief money and grain, the regional interactions in social responses to extreme climate events were analyzed. This paper collected 186 records from historical documents. Regarding the regions as the nodes and the relationships between regions as the links, the spatial patterns of famine-related migration and the allocation of money and grain from 1877 to 1878 were rebuilt. The results show that, firstly, famine-related migration appeared to be spontaneous and short-distanced, with the flow mainly spreading to the surrounding areas and towns. Secondly, as a state administrative action, the relief money and grain from the non-disaster areas were distributed to the disaster areas. However, the distribution of relief grain affected the equilibrium of the food market in non-disaster areas, which led to fluctuations in food prices.

To evaluate the climatic and ecological impacts of anthropogenic activities in global change research, it is essential to reconstruct historical land use and land cover change on regional and global scales. In this study, we reconstructed cropland areas for 54 provinces within the European part of Tsarist Russia (ETR) over the periods of 1500-1914 using historical data, including cropland area, population, grain consumption, and grain yield per unit area. The main results are as follows. (1) Total cropland areas and fractional cropland areas of ETR for 11 time sections (1500 AD, 1540 AD, 1585 AD, 1696 AD, 1719 AD, 1725 AD, 1763 AD, 1796 AD, 1856 AD, 1887 AD and 1914 AD) during 1500-1914 were reconstructed, respectively. The total cropland area of ETR increased from 4.26×104 km2 in 1500 AD to 147.40×104 km2 in 1914 AD. The fractional cropland area increased from 2.40% to 29.20%, and the per capita cropland area decreased from 2.58 ha to 1.13 ha during 1500-1914. (2) Cropland expanded from the central and southwest of ETR to the black soil region, surrounding area of the Volga River, Ukraine region, the new Russia region, and the vicinity of Ural for the increase and migration of population. While in the northern region of ETR, cropland area remained stable due to unfavorable climatic conditions throughout the study period. (3) In 1914 AD, the cropland area and fractional cropland area of each province varied from 0.16×104 km2 and 0.76% to 5.65×104 km2 and 76.68%, respectively. (4) The comparisons show that the cropland areas on the ETR in this study for 1500-1914 are higher than those of the HYDE 3.2 dataset. The main reason might come from the underestimation of per capita cropland areas in HYDE 3.2 dataset, which values remained about 1 ha from 1500 to 1920 in that dataset.

The effectiveness of adaptation to climate change depend on the social resilience. Historical case studies of climate change adaptations would be conducive to better understanding the preferred solution of people with different cultural background, and coping with the risk of the ongoing global climate changes. The relationship among climate change, adaptations and social resilience are analyzed based on the previous researches about famines, agricultural production, trade and migration in Germany during the 16th to the early 20th century. Differences in the primary choices and their effectiveness between Germany and China are also discussed from the perspective of food security. The results are as follows. (1) In the 16th and 17th centuries, the German agricultural system was quite sensitive to the cold and abrupt fluctuated climate, and poor harvests always accompanied by famines in which more than 30% were severe famines. After 1700AD, the severity of famine and its correlation with temperature declined gradually. About 29% famines were merely considered as dearth, and the only severe famine (1770-1772AD) occurred after a back-to-back harvest failure. However, the impact of rainfall extremes on harvest still existed. (2) Germany successfully escaped from famine after 1850AD due to four effective adaptations: ① Planting structure adjustment, like increasing the proportion of rye, was first thought of, but the effectiveness was limited until potatoes became widely accepted. ② The rapid increase in crop yield brought by ago-technology progress reversed the trend of social resilience decreasing with population growth, but was not enough to fully offset the impact of climatic deterioration. ③ The degree of dependence on grain import reached 20% in a short time, which improved the food availability and reduced the famine risk in German mainland. ④ Three emigration waves, following the drought (1844-1846AD) and cooling (1870-1890AD) might have partly alleviated food shortage, especially at a local scale. By 1900AD, German social resilience was nearly 20 times than the scenario of lacking adaptation. (3) In contrast to Germany entered a resilience increasing period since the early 18th century, China maintained the decline of resilience as population pressure increased. Differences might be attributed to their location and culture background. China had long been a unified and powerful empire in east Asia with large internal market and self-sufficient agricultural society, which made it more prone to reduce risk through domestic adjustments, such as internal migration and government relief. When the capacity for disaster relief efforts by the government failed to meet the needs of crisis management, social resilience would drop dramatically. Whereas Germany, located in the continent with a long history of division and amalgamation, had a commercial tradition and was close to the origin of the first industrial revolution, was more willing and likely to find new approaches for food supply ensurance or risk transfer in regional exchanges.

Supplemental material, Supplementary_material for Reconstruction of cropland cover using historical literature and settlement relics in farming areas of Shangjing Dao during the Liao Dynasty, China, around 1100 AD by Zhilei Wu, Xiuqi Fang, Dan Jia and Wanyi Zhao in The Holocene

Modern global cropland products have been widely used to assess the impact of land use and cover change (LUCC) on carbon budgets, climate change, terrestrial ecosystems, etc. However, each product has its own uncertainty, and inconsistencies exist among different products. Understanding the reliability of these datasets is essential for knowing the uncertainties that exist in the study of global change impact forced by cropland reclamation. In this paper, we propose a set of coincidence assessments to identify where reliable cropland distribution is by overlaying ten widely used global land cover/cropland datasets around 2000 AD. A quantitative assessment for different spatial units is also performed. We further discuss the spatial distribution characteristics of different coincidence degrees and explain the reasons. The results show that the high-coincidence proportion is only 40.5% around the world, and the moderate-coincidence and low-coincidence proportion is 18.4% and 41.1%, respectively. The coincidence degrees among different continents and countries have large discrepancies. The coincidence is relatively higher in Europe, South Asia and North America, while it is very poor in Latin America and Africa. The spatial distribution of high and moderate coincidence roughly corresponds to the regions with suitable agricultural conditions and intensive reclamation. In addition to the random factors such as the product&rsquo, s quality and the year it represented, the low coincidence is mainly caused by the inconsistent land cover classification systems and the recognition capability of cropland pixels with low fractions in different products.

Grain price volatility during historical periods is regarded as an important indicator of the impact of climate change on economic system, as well as a key link to adjust food security and social stability. The present study used the wheat prices in Baoding Prefecture, China, during 1736-1850 to explore connections between climatic transition and grain price anomalies in the North China Plain. The main findings were as follows: (1) The grain price change showed an apparent correspondence with climatic transition. The period 1781-1820 was a transition phase, with more extremes and decreased precipitations when the climate shifted from a warm phase to a cold one. Corresponding with the climatic transition, the grain price during 1781-1820 was characterized by that the mean of the original grain price series was significantly higher (lower) than the previous (later) phase, and the variance and anomaly amplitude of the detrended grain price series was the highest during 1736-1850. (2) The correspondence between grain price extremes and drought events occurred in phases. Five grain price extremes occurred following drought events during 1781-1810, while extreme droughts were the direct cause of the grain price spike during 1811-1820. (3) Social stability affected by climate change also played an important role in the grain price spike between 1811 and 1820. Paralleling the pathway of "precipitation-grain production-grain price", climate change could have an impact on grain price via the pathway of "precipitation-grain production-grain price-famine-uprising-grain price", as shown during the Tianli Uprising in 1813. These findings could contribute to an improved understanding of the interaction between climate change and human society during the historical period.

There are still many uncertainties about how climate change affects the development of human society. The impact of climate change is likely to be weakened or amplified by the response and adaptation of the reciprocal feedback process after entering the socio-economical subsystem. The study of the climate change impact processes is the basis for understanding the mechanisms of climate change impacts. Furthermore, long-term research of climate change impacts can provide historical similarity and experience for current or future adaptation of climate change. Ancient China was traditionally an agricultural country. Its food production safety, food supply safety, and food consumption safety reflect the impacts of climate change being transferred from a production subsystem to a population subsystem to an economic subsystem. Based on a conceptual framework of food security, we selected 10-year resolution sequences of grain harvest grades, famine indices, and economic levels in China over the past 2000 years (206 BC–AD 1911) to quantify and recognize the main transmission pathways of climate change impacts during cold and warm units of climate change. Our results were as follows: (1) according to the transmission relationship climate change → grain harvests → famines → economic levels, there are 16 main transmission pathways, including 10 pathways starting from cold units and 6 pathways starting from warm units. (2) The main pathway is dominated by natural factors and socio-economic factors, with each factor set accounting for approximately 50%. However, the probability of the main pathways with socio-economic influence leading toward negative developments was 60% for cold units, and the probability of the main pathways with socio-economic influence leading toward positive developments was 66.7% for warm units. According to the main pathway led by natural factors, of all transmission pathways in cold units (100%), 14.7% of the depressed economy may be more directly related to climate change. However, 32.3% of the prosperous economy may have a more direct relationship with climate change in warm units (100%). (3) Famine is the most important link in the climate change influence on transmission chains regulated by socio-economic factors. Famine reflects both poor harvests due to the natural production subsystem and a lack of grain allocation by the socio-economic subsystem or the government’s ability to eliminate famine. Thus, there may be another pathway of transmission, such as climate change → agricultural yield/grain production → economic prosperity → famine relief (social vulnerability).

The present study aims to compare quantitatively the similarities and differences of transmission processes extending from climate change to grain harvests and economies (macro-economy and fiscal balance) between the Han (206 BC–AD 220) and Tang (AD 618–907) dynasties of China. It is found that both the Han and Tang periods displayed close positive correlations among temperature, grain harvest, macro-economy and fiscal balance and conveyed a positive feedback–oriented transmission pattern with the upgrade of climatic impact level from grain harvest to economic system. Compared with the Han period, the overall linkages among indicators weakened during the Tang period, particularly for the correlation between grain harvest and fiscal balance. The mean temperature during the Tang period was slightly higher but had greater multidecadal variability, coinciding with better performance (and less variations) of macro-economy and fiscal balance (particularly for cold units) and higher variations of grain harvest. It displayed relatively little difference for the main pathways that could be interpreted as climatic impacts during the warm units between the Han and Tang periods, and both approximately 33% of the decades for warm units (100%) ending with fiscal balance/surplus were more likely to be associated with the impacts of temperature change. The difference mainly lies in cold units in the links of ‘cold → poor harvest’ and ‘poor harvest → macro-economic depression’ through the pathway of ‘cold → poor harvest → macro-economic depression/normal economy → fiscal deficiency’. Overall, macro-economy and fiscal system of the Tang period displayed less sensitivity to temperature change and agriculture production in cold period. Those patterns might be related with the unique socio-economic situations such as agricultural fragmentation, southward shift of economic resource and tax system reform during the later Tang Dynasty.

By merging reconstructed phenological series from published articles and observations of China Phenology Observation Network (CPON), the first blooming date of Amygdalus davidiana (FBA) in Beijing between 1741 and 2000 is reconstructed. The Butterworth method is used to remove the multi-year variations for generating the phenological series of annual variations in the first blooming date of A. davidiana. The extreme delay years in the phenological series are identified using the percentage threshold method. The characteristics of the extreme delays and the correspondence of these events with natural forcings are analysed. The main results are as follows. In annual phenological series, the extreme delays appeared in single year as main feature, only A.D.1800-1801, 1816-1817 and 1983-1984 were the events of two consecutively extreme years. Approximately 85% of the extreme delays occurred during 1-2 years after the large volcanic eruptions (VEI ≥ 4) in the eastern rim or the western rim of the Pacific Ocean, as the same proportion of the extreme delays followed El Niño events. About 73% years of the extreme delays fall in the valleys of sunspot cycles or the Dalton minimum period in the year or the previous year. According to the certainty factor (CF), the large eruptions have the greatest influence to the extreme delays; sunspot activity is the second, and ENSO is the last one. The extreme phenological delayed year is most likely to occur after a large eruption, which particularly occurs during El Niño year and its previous several years were in the descending portion or valley of sunspot phase.

Relic archeological settlement is used to indicate the development of agriculture. We extracted 8865 relic archeological settlements from theAtlas of Chinese Cultural Relicsto analyze how the spatiotemporal distribution of archaeological settlements was influenced by temperature changes and social factors during the last millennium. During the Liao dynasty (AD 916–1125) and Jin dynasty (AD 1115–1234) in the Medieval Warm Period (MWP), a large number of settlements indicated the development of agriculture as far north as 47°N. The warm climate of the MWP provided sufficient heat resources to promote the implication of positive policies of the Liao and Jin dynasties to develop agriculture and settlements. By contrast, during the dynasties of Yuan (AD 1279–1368), Ming (AD 1368–1644), and Qing (AD 1644–1911) in the Little Ice Age (LIA), the number of settlements declined drastically, and the northern boundary of the settlement distribution retreated by 3–4 degrees of latitude to modern Liaoning Province. Although the southward retreat of the settlements and related agriculture occurred in the cold climate of the LIA, it could not be completely explained by the drop in temperature. Social factors including nomadic customs, ethnic policies, and postal road systems played more important roles to the northern boundaries of the settlement distributions during the Yuan, Ming, and Qing dynasties.

As a direct result of climate change and extreme weather events, refugee migration has attracted worldwide concern. In this study, we select the North China Plain (NCP) as the case area, where the capital (Beijing) is located during the late Qing dynasty (1790–1911). Based on records of porridge charity, public order (inside Beijing), and revolt events (outside Beijing) in ancient official documents, the interaction between behavior of refugees and the governmental management after floods and droughts is analyzed. The main conclusions can be summarized as follows. (1) Flood/drought has become an important triggering factor of refugee migration during 1790–1911 besides the social factors (e.g., man-land contradiction, fiscal crisis). (2) A negative interaction has existed between the government and refugees throughout the late nineteenth century, which leads to social disorder in the mid-1890s in Beijing and large-scale revolt (the Boxers Movement) in 1900 in the NCP. (3) The negative interaction has been finally ended by the adjustment of migration policy at the beginning of the twentieth century, which officially permits the refugees from the NCP to emigrate to Manchuria and Mongolia outside the Great Wall. The historical case study may provide valuable lessons for the successful adaptation of human societies to future similar occurrences, and will enhance our understanding of the interactions between climate change and social vulnerability.

A novel highly controllable process of Carbon Encapsulated Magnetic Nanoparticles (CEMNs) synthesis in arc discharge plasma has been developed. In this work, both the size distribution and the purity of the CEMNs have been made more controllable by adding an external magnetic field. It is shown that with the increase of the external magnetic field, the CEMNs get a better separation from the carbon impurities and the size distribution become narrower. This conclusion is valid for Fe, Ni and Fe+Ni CEMNs synthesis. In order to assess biomedical potential of these CEMNs, the cytotoxicity has also been measured for the human breast adenocarcinoma cell line MDA-MB-231. It was concluded that the CEMNs with the concentration in cell of about 0.0001-0.01ug/ml are not toxic.

The study on the relationship of abandoned settlements and climate change in the oases could provide a historical reference for understanding human responses to present and future global warming in the arid zone. A total of 554 abandoned historical settlements in Xinjiang Uygur Autonomous Region, China, were used to examine the relationship between abandoned settlements and temperature change over the past 2000 years. The analysis covered dynastic epochs from the Han Dynasty (206BC–220AD) to the Qing Dynasty (1644AD–1911AD) in the oases of Xinjiang. Greater density of settlements was found at the oases larger than 2000 km2, which were more stable and less sensitive to climate change compared to smaller oases. Settlements flourished at small oases and the middle and lower reaches of rivers during warm periods and shrank back to piedmont basins and upstream alluvial fans during cold periods. These results demonstrated responses of oasis agriculture to climate change.

In this study, 89 records of spring phenophases of plants and lake melting dates in Beijing from A.D. 1741 to 1832 were extracted from the poems written by the Qianlong, Jiaqing, and Daoguang emperors during the Qing Dynasty. Based on a phenology transformation model, all of these spring phenological records were converted into the first blooming date of Amygdalus davidiana for A.D. 1741–1832. Then, a springtime temperature anomaly series for A.D. 1741–1832 was reconstructed based on modern (1951–1980) correlation between the first blooming date of A. davidiana and the mean springtime (March–May) temperature. The main results are as follows. (1) The spring phenological and temperature series for Beijing were successfully dated back to A.D. 1741. (2) A.D. 1790 was the turning point of the spring phenology change between 1741 and 1832; specifically, the average first blooming date of A. davidiana had advanced by 4.84 days compared to the present (A.D. 1951–1980), during 1741 to 1789, and was delayed by 0.14 days during 1790 to 1832. (3) The mean springtime temperature in A.D. 1741–1789 was about 0.48 °C warmer than the present (A.D. 1951–1980) in Beijing. (4) The annual-scale variation of the phenological series during A.D. 1790–1832 was greater than that in A.D. 1741–1789.

Articular cartilage repair and regeneration are a challenging problem worldwide due to the extremely weak inherent regenerative capacity of cartilaginous tissue. As an emerging tissue engineering scaffold fabrication technology, 3D bioprinting has shown great promise in fabricating customizable artificial tissue matrices with hierarchical structures. The goal of the present study is to investigate 3D bioprinted graphene oxide (GO)-doped gelatin–based scaffolds for promoting chondrogenic differentiation of human bone marrow mesenchymal stem cells (MSCs). In the current study, GO-gelatin methacrylate (GelMA)–poly (ethylene glycol) diacrylate (PEGDA) was prepared as a biocompatible photopolymerizable bioink. GO, a multifunctional carbon based nanomaterial, was incorporated into the bioink for promoting chondrogenic differentiation. Finally, the 3D printed GelMA-PEGDA-GO scaffold with hierarchical structures was fabricated via our novel table-top stereolithography-based printer. Results showed that GelMA-PEGDA-GO scaffolds greatly promoted the glycosaminoglycan, and collagen levels after GO induced chondrogenic differentiation of hMSCs. Moreover, the Collagen II, SOX 9, and Aggrecan gene expressions associated with chondrogenesis were greatly promoted on the scaffolds. This study demonstrated that customizable 3D printed GelMA-PEGDA-GO scaffolds are excellent candidates for promoting chondrogenic differentiation of hMSCs and are therefore promising candidates for future cartilage regenerative medicine applications.

This study is intended to investigate the patterns for the temporal and spatial changes of catastrophic river floodings which took place in the Lower Yellow River, based on the available records collected from historical documents, and rearranged in a GIS database. A series of catastrophic river floodings from AD 960 to 1938 was reconstructed, and their temporal and spatial variations were analyzed, which leads to the conclusions, among others. (1) The increasing trend of frequency of catastrophic river floodings in the Lower Yellow River is not so significant in the past 1000 years. (2) Most dike breachings and overtoppings occurred near the apex of the Yellow River Alluvial Fan, and the number of dike breaching and overtopping was gradually reduced as the elevation decreased. (3) Under different spatio-temporal backgrounds, dike breaching and overtopping developed either downstream or upstream, which is evidenced by both the downstream movement for large temporal and spatial scales in dike breaching and overtopping places in AD 1128–1344 and 1391–1447 and the upstream movement for small temporal and spatial scales in AD 960–969, 1730–1761, and 1807–1819.

Arc discharge is one of the most efficient and environmental friendly method to synthesize Single Wall Carbon Nanotube (SWCNT). However, due to the ultra-fast synthesis procedure, localization of the SWCNT synthesis in an arc discharge plasma volume in situ has been a long standing problem. This relates to the ability of controlling volumetric synthesis of nanostructures in plasmas in general. In order to better understand the mechanism of the nanotube growth in plasma, we have developed an actuator driven high-speed system that is able to extract material from the arc plasma volume during the synthesis procedure. The majority of the SWCNTs produced using arc discharge method are semiconducting with diameter of about 1.5 nm. It is shown that the growth region of SWCNTs is between 3 mm and 11 mm away from the center of the arc discharge. Dependent on the origin, the length of SWCNTs increases non-monotonically up to 500 nm, while diameter and chirality only slightly depend on the growth position.

The quality of global cropland products could affect our understanding of the impacts of cropland reclamation on global changes. With the advancement of remote sensing technology, several global land cover products and synergistic datasets have been developed in recent decades. However, there are still some disagreements among the global cropland datasets. In this paper, we proposed a new synergistic method that integrates the reliability of spatial distribution and cropland fraction on a pixel scale, and developed a modern (around 2000 C.E.) fractional cropland dataset with a 1 km × 1 km spatial resolution on the basis of the spatial consistency of cropland reclamation intensity derived from multi-sets of global land cover products. The main conclusions are shown as follows: (1) The accuracy of spatial distribution assessed by validation samples in this synergistic dataset reaches 87.6%, and the dataset also has a moderate amount of cropland pixels when compared with other products. (2) The reliability of cropland fraction on the pixel scale had been highly improved, and most cropland pixel has a higher fraction (over 90%) in this dataset. The “L” shape of the histogram of pixel numbers with different reclamation intensities is reasonable because it is consistent with the up-scaling results derived from satellite-derived products with high spatial resolutions and the expert knowledge on cultivation. (3) The cropland areas in this non-calibrated result are generally closer to that of FAOSTAT on scales from global to national when compared to other non-calibrated synergistic datasets and original satellite-derived products. (4) The reliability of the synergistic result developed by this method might be decreased to some degree in the regions with high discrepancies among the original multi-sets of cropland datasets.

Continuous detection of dispersion and residence of volcanic plumes in troposphere and lower stratosphere is vitally important for improving the understanding on the role of volcano eruptions in climate change. We report a 3-month continuous detection of dispersion and residence of volcanic plumes in the troposphere and stratosphere generated from the volcanic SO2 erupted by Nabro in Eritrea on June 12th, 2011 observed by the OMI sensor. The background SO2 concentration of 3 different height layers in troposphere and lower stratosphere were estimated by the 3-year-average daily concentration of monthly SO2 in 2005, 2007 and 2013, when there were no large explosive volcanic eruptions occurring. We also traced the diffusion path and the concentration of volcanic SO2 for the first 3 months after Nabro's eruption, and detected the appearance and dissipation of sulfate aerosols, which is a product converted from volcanic SO2. The results show that after Nabro erupted on June 12th, the volcanic plumes spread to middle latitudes (30 degrees N -60 degrees N) of Northern Hemisphere and loading by westerly jet. The volcanic SO2 in middle troposphere layer (TRM) and lower troposphere layer (TRL) stopped eastward spreading, and dissipated over the western Pacific Ocean on June 23rd. On June 26th, the volcanic SO2 in upper troposphere and lower stratosphere (STL) reached Mexico in Central America, and almost encircled the low latitudes and parts of middle latitudes. On June 28th, the volcanic SO2 plume showed an even distribution in STL. 37 days after the eruption, the volcanic SO2 in STL encircled the Northern Hemisphere evenly, sulfate aerosols in STL largely covered the low and middle latitudes and the daily concentration of SO2 was still higher than the background value. One month after the eruption, the global mean daily concentration of SO2 dropped to the normal value, but the daily concentration of SO2 and sulfate aerosols in low latitudes remained high, and dissipated not earlier than 3 months after the eruption of Nabro.

This chapter introduces, by literature reviews, the issue of the links and processes behind climate change, environmental change, and socio-culture change in the past at the ancient Silk Road region. Analyses of the changes of the socio-environment system in this area enhance our understanding on the regular patterns of coupled natural and social evolution, and is thus of important theoretical and practical significance. We argue that the cross-cutting theme has been to reach beyond simple explanations of environmental or human determinism, but social resilience under environmental impacts. Studies indicate both that climate conditions significantly influence human socio-cultural systems and that the socio-culture systems are certainly resilient to climate impacts. This chapter also summarizes the scope of all chapters in this book by illustrating the specific topics, research areas, focused periods and their inner relationships. The conclusion further summarizes the recent research states on past socio-environmental dynamics and the findings achieved in this book, as well as some outlooks.