This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation ...This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation in China has exhibited significant 50–70-yr, 100–120-yr, and 200–250-yr cycles. Results also show that the amplitudes of decadal and centennial temperature variation were 1.3℃ and 0.7℃, respectively, with the latter significantly correlated with long-term changes in solar radiation, especially cold periods, which correspond approximately to sunspot minima. The most rapid warming in China occurred over AD 1870–2000, at a rate of 0.56°± 0.42℃（100 yr）^（-1）; however, temperatures recorded in the 20 th century may not be unprecedented for the last 2000 years, as data show records for the periods AD 981–1100 and AD1201–70 are comparable to the present. The ensemble means of dryness/wetness spatial patterns in eastern China across all centennial warm periods illustrate a tripole pattern： dry south of 25°N, wet from 25°–30°N, and dry to the north of 30°N. However, for all centennial cold periods, this spatial pattern also exhibits a meridional distribution. The increase in precipitation over the monsoonal regions of China associated with the 20 th century warming can primarily be attributed to a mega El Nino–Southern Oscillation and the Atlantic Multidecadal Oscillation. In addition, a significant association between increasing numbers of locusts and dry/cold conditions is found in eastern China. Plague intensity also generally increases in concert with wetness in northern China, while more precipitation is likely to have a negative effect in southern China.展开更多
A pollen study was conducted on an alpine marsh sediment in the Son Kul Basin and was allowed to reconstruct changes in vegetation dynamics and climatic information in the western Tianshan Mountains during the past 20...A pollen study was conducted on an alpine marsh sediment in the Son Kul Basin and was allowed to reconstruct changes in vegetation dynamics and climatic information in the western Tianshan Mountains during the past 2000 years.Pollen diagram reveals that regional vegetation is dominated by alpine meadow in the past 2000 years,being similar with modern vegetation components in the basin.The Artemisia/Chenopodiaceae-indicated moisture exhibits a warm-dry Roman Warm Period(RWP,~0-~500 AD),a cold-dry Dark Ages Cold Period(DACP,~500-~800 AD),a warm-wet Medieval Warm Period(MWP,~800-~1350 AD),a cold-dry Little Ice Age(LIA,~1350-~1850 AD)and a warm-dry Current Warm Period(CWP,since~1850 AD).Our pollen-based moisture reconstructions are supported by other nearby moisture records.Combined with other pollen data in the western Tianshan Mountains,we found that the vegetation was relatively stable before~1650-~1750 AD and the anthropogenic activities obviously intensified afterwards(especially at the middle-elevation sites).Further work involving more and higher-resolution palaeovegetation records would contribute to fully understand the information on the complex links between environmental,climatic and anthropogenic changes in the western Tianshan Mountains.展开更多
The Fourth Assessment Report of IPCC(IPCC AR4)concluded that average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than that of any other 50-year period in the las...The Fourth Assessment Report of IPCC(IPCC AR4)concluded that average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than that of any other 50-year period in the last 500 years and likely the highest in at least the past 1300 years.However,after evaluating Global or Northern Hemisphere temperature change series derived from ice cores,tree rings,展开更多
The historical movements of relative sea level(RSL)reflect the geomorphological dynamics around coastal regions in the past,and reconstructing the RSL curve contributes to the prediction of future RSL movements.On the...The historical movements of relative sea level(RSL)reflect the geomorphological dynamics around coastal regions in the past,and reconstructing the RSL curve contributes to the prediction of future RSL movements.On the basis of the sediment sequence and optical stimulated luminescence(OSL)dating data of three boreholes in the Yellow River Delta(YRD),the positions of paleo-coastlines and the movements of RSL in the last 2000 years were reconstructed.The main results are as follows:1)the YRD coast transformed from a tide-dominated silty coast to a wave-dominated sandy coast and back to a tide-dominated silty coast in the last 2000 years.2)The sand layers consisting of shell fragments indicated the locations of the coastline in 1855 AD,893 AD,and 40 BC,and their top elevations were close to the mean high water level in the corresponding years.3)The mean sea level elevation in 79 BC,1019 AD,and 1800 AD relative to the modern sea level was -4.52,-4.52,and-2.92 m,respectively.4)The RSL was almost stagnant during 79 BC-1019 AD,rose slowly during 1019-1800 AD due to the reverse change of global climate from the Little Ice Age to the Medieval Warm Period,and rose significantly after 1800 AD due to the warm period.5)The movement of RSL controlled the surface slope of YRD,which was a slope of approximately 0.022‰ at 893 AD,an inverted slope of 0.144‰ at 1855 AD,and a slope of 0.075‰ recently.These findings indicate that the modern YRD is far from being abandoned in the future,providing a historical geomorphological basis for the management of the Yellow River Estuary.展开更多
The spatial patterns of precipitation anomalies during five 30-yr warm periods of 691-720, 1231-1260, 1741-1770, 1921-1950, and 1981-2000 were investigated using a dryness/wetness grading dataset covering 48 stations ...The spatial patterns of precipitation anomalies during five 30-yr warm periods of 691-720, 1231-1260, 1741-1770, 1921-1950, and 1981-2000 were investigated using a dryness/wetness grading dataset covering 48 stations from Chinese historical documents and 22 precipitation proxy series from natural archives. It was found that the North China Plain （approximately 35^-40~N, east of 105~E） was dry in four warm periods within the centennial warm epochs of 600-750, the Medieval Warm Period （about 900-1300） and after 1900. A wet condition prevailed over most of China during 1741-1770, a 30-yr warm peak that occurred during the Little Ice Age （about 1650-1850）. The spatial pattern of the precipitation anomaly in 1981-2000 over East China （25^-40~N, east of 105~E） is roughly consistent with that in 1231 1260, but a difference in the precipitation anomaly appeared over the Tibetan Plateau. The spatial patterns of the precipitation anomalies over China varied between all five 30-yr warm periods, which implies that the matching pattern between temperature and precipitation change is multiform, and the precipitation anomaly could be positive or negative when a decadal warm climate occurs in different climate epochs. This result may provide a primary reference for the mechanism detection and climate simulation of the precipitation anomaly of the future warm climate.展开更多
The precipitation at 17 stations over the middle and lower reaches of the Yellow River is reconstructed during the period of 1736―1910, using the snow and rainfall records in the Qing Dynasty, together with the instr...The precipitation at 17 stations over the middle and lower reaches of the Yellow River is reconstructed during the period of 1736―1910, using the snow and rainfall records in the Qing Dynasty, together with the instrumental observation data of precipitation and farmland soil moisture content. The soil physics model related to rainfall infiltration and the surface water bal-ance equation are taken as main reconstruction methodology. The field infiltration experiment by artificial rainfall is conducted to check the reliability. And the precipitation series over the middle and lower reaches of the Yellow River and its 4 sub-regions are established, going back to 1736. Analysis of the time series indicates that the abrupt change of precipitation from high to low oc-curs around 1915 over the middle and lower reaches of the Yellow River. During the three peri-ods of 1791―1805, 1816―1830 and 1886―1895, the precipitation is markedly higher than the mean of the series. While both the periods of 1916―1945 and 1981―2000 are characterized by less precipitation. Three periodicities of 22―25a, 3.9a and 2.7a are shown in the precipitation fluctuation over the middle and lower reaches of the Yellow River. Moreover, the periodical signal of 22―25a becomes weaker and weaker since the abrupt change of 1915 and disappears in the late 1940s, and then the periodical signal of 35―40a appears instead.展开更多
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,...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 recon- struction 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, tem- perature variations for the last 1000 years are examined, with special focus placed on the characteris- tics of the Medieval Warm Period (MWP), the Little Ice Age (LIA), and Modern Warming (MW).展开更多
China is distinguished by a prominent monsoonal climate in the east of the country, a continental arid climate in the northwest and a highland cold climate on the Qinghai-Tibet Plateau. Because of the long history of ...China is distinguished by a prominent monsoonal climate in the east of the country, a continental arid climate in the northwest and a highland cold climate on the Qinghai-Tibet Plateau. Because of the long history of Chinese civilization, there are abundant and well-dated documentary records for climate variation over the whole of the country as well as many natural archives（e.g., tree-rings, ice cores, stalagmites, varved lake sediments and corals） that enable high-resolution paleoclimatic reconstruction. In this paper, we review recent advances in the reconstruction of climate and extreme events over the last 2000 years in China. In the last 10 years, many new reconstructions, based on multi-proxies with wide spatial coverage, have been published in China. These reconstructions enable us to understand the characteristics of climate change across the country as well as the uncertainties of regional reconstructions. Synthesized reconstructed temperature results show that warm intervals over the last 2000 years occurred in AD 1–200, AD 551–760, AD 951–1320, and after AD 1921, and also show that cold intervals were in AD 201–350, AD 441–530, AD 781–950, and AD 1321–1920. Extreme cold winters, seen between 1500 and 1900, were more frequent than those after 1950. The intensity of regional heat waves, in the context of recent global warming, may not in fact exceed natural climate variability seen over the last 2000 years. In the eastern monsoonal region of China, decadal, multi-decadal and centennial oscillations are seen in rainfall variability. While the ensemble mean for drought/flood spatial patterns across all cold periods shows a meridional distribution, there is a tri-pole pattern with respect to droughts south of 25°N, floods between 25° and 30°N, and droughts north of 30°N for all warm periods. Data show that extreme drought events were most frequent in the periods AD 301–400, AD 751–800, AD 1051–1150, AD 1501–1550, and AD 1601–1650, while extreme flood events were frequent in the periods AD 101–150, AD 251–300, AD 951–1000, AD 1701–1750, AD 1801–1850, and AD 1901–1950. Between AD 1551–1600, extreme droughts and flood events occurred frequently. In arid northwest China, climate was characterized by dry conditions in AD 1000–1350, wet conditions in AD 1500–1850, and has tended to be wet over recent decades. On the northeastern Qinghai-Tibet Plateau, centennial-scale oscillations in precipitation have occurred over the last 1000 years, interrupted by several multidecadal-scale severe drought events. Of these, the most severe were in the 1480 s and 1710 s. In southwest China, extreme droughts as severe as those seen in Sichuan and Chongqing in 2006 are known to have occurred during historical times.展开更多
The total 15 severe droughts are discovered with the aid of the 'RetrievalSystem of Chinese Historical Climate Records' for the last 1000 years. The droughts are extensive toenvelope more than 4 provinces and ...The total 15 severe droughts are discovered with the aid of the 'RetrievalSystem of Chinese Historical Climate Records' for the last 1000 years. The droughts are extensive toenvelope more than 4 provinces and persistent to cover 3 yr or more, and their severity isequivalent to or in excess of that in the 1930s in China. According to the documentary records andrestorations it can be inferred that most droughts are more severe than those in the last 50 years.The 15 droughts may either occur warm or in a cold climate background, with 11 of the 15 cases inthe cold phase. This indicates the difference in climate correspondence between China and northernAmerica, showing the severity of the events in China to be in a cold instead of a warm climatesituation. That is likely to relate to the monsoon climate in eastern Asia.展开更多
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 to...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 km^2, 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.展开更多
Objective: To study the effects of starting antiretroviral treatment (ART) prior the age of two years on the growth (height and weight) of HIV-infected children. Methodology: This was a retrospective cohort study. HIV...Objective: To study the effects of starting antiretroviral treatment (ART) prior the age of two years on the growth (height and weight) of HIV-infected children. Methodology: This was a retrospective cohort study. HIV-infected children on ART aged less than 15 years were divided into two groups Group 1 (G1) comprising children who started ART prior 2 years and Group (G2) those put on treatment thereafter. Main Measures: Percentage of children with growth retardation measured by Height for Age (H/A) and Weight for Age (W/A) Results: In total, we included 90 subjects. The median age was 10 years with a slight female predominance (51.2%). Most children were asymptomatic at the time of the study (96.6%), compliant with treatment (81%), 54.8% of children were on cotrimoxazole, 33% knew their status. At initiation, underweight was predominant in group 1 compared to group 2 (52% versus 29.5%;p = 0.015). Conversely, stunted growth predominated in G2 compared to G1 but without significant difference (38% versus 50%;p = 0.147). At the time of our study (median age of 10 years), catch-up height and weight predominated in G1 compared to G2;only a small proportion remained below −2SD (4% versus 18.2%;p = 0.015 and 9% versus 29.5%;p = 0.006 respectively for underweight and stunted growth). Conclusion and Global Health Implications: Growth retardation was common at ART initiation. Catch-up in height was more evident in the early treatment group. Initiation of ART before the age of 2 years rather influences children’s height than weight. The result of this study further emphasizes the need of early ART and closed clinical monitoring to better assess the impact of ART in areas with high rates of undernutrition.展开更多
In 1993,the World Bank released a global report on the efficacy of health promotion,introducing the disability-adjusted life years(DALY)as a novel indicator.The DALY,a composite metric incorporating temporal and quali...In 1993,the World Bank released a global report on the efficacy of health promotion,introducing the disability-adjusted life years(DALY)as a novel indicator.The DALY,a composite metric incorporating temporal and qualitative data,is grounded in preferences regarding disability status.This review delineates the algorithm used to calculate the value of the proposed DALY synthetic indicator and elucidates key methodological challenges associated with its application.In contrast to the quality-adjusted life years approach,derived from multi-attribute utility theory,the DALY stands as an independent synthetic indicator that adopts the assumptions of the Time Trade Off utility technique to define Disability Weights.Claiming to rely on no mathematical or economic theory,DALY users appear to have exempted themselves from verifying whether this indicator meets the classical properties required of all indicators,notably content validity,reliability,specificity,and sensitivity.The DALY concept emerged primarily to facilitate comparisons of the health impacts of various diseases globally within the framework of the Global Burden of Disease initiative,leading to numerous publications in international literature.Despite widespread adoption,the DALY synthetic indicator has prompted significant methodological concerns since its inception,manifesting in inconsistent and non-reproducible results.Given the substantial diffusion of the DALY indicator and its critical role in health impact assessments,a reassessment is warranted.This reconsideration is imperative for enhancing the robustness and reliability of public health decisionmaking processes.展开更多
Background: This study assessed the effect of a nutrition education intervention. This intervention aimed to improve the knowledge, attitudes, and practices of mothers on food safety in the peri-urban areas of Bobo-Di...Background: This study assessed the effect of a nutrition education intervention. This intervention aimed to improve the knowledge, attitudes, and practices of mothers on food safety in the peri-urban areas of Bobo-Dioulasso in Burkina Faso. Methods: A total of 243 mothers of children under 5 years in the peri-urban of Bobo-Dioulasso were administered the FAO questionnaire for food safety knowledge, attitudes, and practices assessment during two cross-sectional surveys, before and after the intervention, in January and October 2017. The intervention included two components consisting of a theoretical phase (counselling and discussion) and cooking demonstrations implemented for ten months. To account for the before-and-after design of the study, the McNemar’s test was used to assess the effect of the intervention on food safety KAP of mothers of children under 5 years. Results: The mean age of mothers was 29 ± 6.2 years and 50.6% of them were between 20 and 29 years old. One for knowledge (cooking thoroughly with, p-value = 0.0001) and another for attitudes (perceived benefits of reheating leftovers before eating them, p-value = 0.0001), significantly increased after the intervention. In terms of food safety practices, all the indicators (cleaning of dirty surfaces, plates and utensils and storage of perishable foods) significantly increased (all p = 0.0001 Conclusion: This study provided some evidence of an effective nutrition education intervention for improving maternal KAP on food safety for their child’s feeding.展开更多
Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of cl...Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change,especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which the reconstruction of the historical development of mangrove forests using an effective indicator has been regarded as a necessary strategy for designing a predictable model. As the primary product of mangrove forest, it is reasonable that the content of leaf fragments of mangrove(CLFM) buried in sediments in the form of sub-fossils potentially has the same indicative function for the development of mangrove forests as that of widely-used mangrove pollen. In this study, the leaf fragments of mangrove in two sediment cores(YLW02 and YLW03) drilled in the Yingluo Bay in Guangxi, Southwest China were picked out and weighted for calculation of CLFM, which was used as an indicator of mangrove development after examination of parallelism and a statistical correlation of the CLFM with the concentration of mangrove pollen. The results clearly show that the vertical distribution of the CLFM for the core taken from the landward margin of mangrove forests(YLW03) only parallels that of the local mangrove species(Rhizophora. stylosa) with a significantly positive correlation(R=0.56, P=0.05), while the vertical distribution of the CLFM for the core taken from the interface between seaward margin of mangrove forest and the trunk of tidal creeks of the bay(YLW02) parallels the summed concentration of mangrove pollen(SCMP) with a more positive correlation than that of YLW03(R=0.85, P=0.01), indicating that the trunk outlet of tidal creeks must have been the site where mangrove production gathered from the overall forest rather than from local production. The variations in the CLFM of both cores indicate that overall the mangrove forests in the Yingluo Bay have increasingly flourished over the last 130 years except for the interval of 1940–1950 AD in response to an increase in air temperature and decrease in rainfall, which would have resulted in an increase in seawater salinity;while the coupled extreme increases in air temperature and in rainfall in summer, which would have resulted in extreme decreases in seawater salinity, would be responsible for the relative degradation of mangrove forests in the interval of 1940–1950 AD.展开更多
By summarizing the results of debris flow studies in China and integating with the knowledge and experience gained by the authors in their research work, thes paper makes a review and outlook on debris flow studies in...By summarizing the results of debris flow studies in China and integating with the knowledge and experience gained by the authors in their research work, thes paper makes a review and outlook on debris flow studies in China in the last 30 years. Corresponding opinions and suggestions are proposed in view of the circumstances and disasters in China.展开更多
Using 24 proxy temperature series, the rates of temperature change in China are analyzed at the 30- to 100-year scales for the past 2000 years and at the 10-year scale for the past 500 years. The results show that, at...Using 24 proxy temperature series, the rates of temperature change in China are analyzed at the 30- to 100-year scales for the past 2000 years and at the 10-year scale for the past 500 years. The results show that, at the 100-year scale, the warming rate for the whole of China in the 20th century was only 0.6±1.6℃/100 a （interval at the 95% confidence level, which is used here- after）, while the peak warming rate for the period from the Little Ice Age （LIA） to the 20th century reached 1.1_＋1.2~C/100 a, which was the greatest in the past 500 years and probably the past 2000 years. At the 30-year scale, warming in the 20th century was quite notable, but the peak rate was still less than rates for previous periods, such as the rapid warming from the LIA to the 20th century and from the 270s-290s to 300s-320s. At the 10-year scale, the warming in the late 20th century was very evident, but it might not be unusual in the context of warming over the past 500 years. The exact timing, duration and magnitude of the warming peaks varied from region to region at all scales. The peak rates of the 100-year scale warming in the AD 180s-350s in northeastern China as well as those in the 260s-410s and 500s-660s in Tibet were all greater than those from the mid-19th to 20th century. Meanwhile, the rates of the most rapid cooling at scales of 30 to 100 years in the LIA were promi-nent, but they were also not unprecedented in the last 2000 years. At the 10-year scale, for the whole of China, the most rapid decadal cooling in the 20th century was from the 1940s to 1950s with a rate of -0.3±0.6℃/10 a, which was similar to rates for periods before the 20th century. For all regions, the rates of most rapid cooling in the 20th century were all less than those for previous periods.展开更多
The general characteristics of climate changes over the past 2000 years in China,regional differences and uncertainties were analyzed based on the recently peer-reviewed high time-resolution climatic reconstructions.T...The general characteristics of climate changes over the past 2000 years in China,regional differences and uncertainties were analyzed based on the recently peer-reviewed high time-resolution climatic reconstructions.The results showed that there exists four warm periods of the temperature variation in China since the Qin Dynasty,including the western and eastern Han Dynasties(200 BC-AD 180),the Sui and Tang dynasties(541-810),the Song and Yuan dynasties(931-1320),and the 20th century,and three cold phases involving the Wei,Jin,and North-South Dynasties(181-540),the late Tang Dynasty(811-930),and the Ming and Qing dynasties(1321-1920).The Song and Yuan warm period is consistent with the Medieval Warm Period over the Northern Hemisphere,and the cold phases of the North-South Dynasties and the Ming and Qing dynasties are paralleled to the Dark Ages Cold Period and the Little Ice Age,respectively.The 13th-15th century could be a shift to the wet condition of the climate,and the low precipitation variability is exhibited in western China prior to 1500.In the context of the climate warming,the pattern of the drought in north and flood in south is prevalent over the eastern China.In addition,the published reconstructions have a high level of confidence for the past 500 years,but large uncertainties exist prior to the 16th century.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA050800)the Key Program of the Chinese Academy of Sciences (Grant No. KJZD-EW-TZ-G10)the National Natural Science Foundation of China (Grant No.41671201 and 91525101)
文摘This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation in China has exhibited significant 50–70-yr, 100–120-yr, and 200–250-yr cycles. Results also show that the amplitudes of decadal and centennial temperature variation were 1.3℃ and 0.7℃, respectively, with the latter significantly correlated with long-term changes in solar radiation, especially cold periods, which correspond approximately to sunspot minima. The most rapid warming in China occurred over AD 1870–2000, at a rate of 0.56°± 0.42℃（100 yr）^（-1）; however, temperatures recorded in the 20 th century may not be unprecedented for the last 2000 years, as data show records for the periods AD 981–1100 and AD1201–70 are comparable to the present. The ensemble means of dryness/wetness spatial patterns in eastern China across all centennial warm periods illustrate a tripole pattern： dry south of 25°N, wet from 25°–30°N, and dry to the north of 30°N. However, for all centennial cold periods, this spatial pattern also exhibits a meridional distribution. The increase in precipitation over the monsoonal regions of China associated with the 20 th century warming can primarily be attributed to a mega El Nino–Southern Oscillation and the Atlantic Multidecadal Oscillation. In addition, a significant association between increasing numbers of locusts and dry/cold conditions is found in eastern China. Plague intensity also generally increases in concert with wetness in northern China, while more precipitation is likely to have a negative effect in southern China.
基金financially supported by Western Young Scholar Program-B of Chinese Academy of Sciences(No.2018-XBQNXZ-B-020)China Postdoctoral Science Foundation(No.2019M663864)+2 种基金National Natural Science Grants of China(No.41803024)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA20020101)Open Fund of State Key Laboratory of Loess and Quaternary Geology(No.SKLLQG2011)。
文摘A pollen study was conducted on an alpine marsh sediment in the Son Kul Basin and was allowed to reconstruct changes in vegetation dynamics and climatic information in the western Tianshan Mountains during the past 2000 years.Pollen diagram reveals that regional vegetation is dominated by alpine meadow in the past 2000 years,being similar with modern vegetation components in the basin.The Artemisia/Chenopodiaceae-indicated moisture exhibits a warm-dry Roman Warm Period(RWP,~0-~500 AD),a cold-dry Dark Ages Cold Period(DACP,~500-~800 AD),a warm-wet Medieval Warm Period(MWP,~800-~1350 AD),a cold-dry Little Ice Age(LIA,~1350-~1850 AD)and a warm-dry Current Warm Period(CWP,since~1850 AD).Our pollen-based moisture reconstructions are supported by other nearby moisture records.Combined with other pollen data in the western Tianshan Mountains,we found that the vegetation was relatively stable before~1650-~1750 AD and the anthropogenic activities obviously intensified afterwards(especially at the middle-elevation sites).Further work involving more and higher-resolution palaeovegetation records would contribute to fully understand the information on the complex links between environmental,climatic and anthropogenic changes in the western Tianshan Mountains.
文摘The Fourth Assessment Report of IPCC(IPCC AR4)concluded that average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than that of any other 50-year period in the last 500 years and likely the highest in at least the past 1300 years.However,after evaluating Global or Northern Hemisphere temperature change series derived from ice cores,tree rings,
基金supported financially by the National Natural Science Foundation of China(Nos.42330406 and 42476163)。
文摘The historical movements of relative sea level(RSL)reflect the geomorphological dynamics around coastal regions in the past,and reconstructing the RSL curve contributes to the prediction of future RSL movements.On the basis of the sediment sequence and optical stimulated luminescence(OSL)dating data of three boreholes in the Yellow River Delta(YRD),the positions of paleo-coastlines and the movements of RSL in the last 2000 years were reconstructed.The main results are as follows:1)the YRD coast transformed from a tide-dominated silty coast to a wave-dominated sandy coast and back to a tide-dominated silty coast in the last 2000 years.2)The sand layers consisting of shell fragments indicated the locations of the coastline in 1855 AD,893 AD,and 40 BC,and their top elevations were close to the mean high water level in the corresponding years.3)The mean sea level elevation in 79 BC,1019 AD,and 1800 AD relative to the modern sea level was -4.52,-4.52,and-2.92 m,respectively.4)The RSL was almost stagnant during 79 BC-1019 AD,rose slowly during 1019-1800 AD due to the reverse change of global climate from the Little Ice Age to the Medieval Warm Period,and rose significantly after 1800 AD due to the warm period.5)The movement of RSL controlled the surface slope of YRD,which was a slope of approximately 0.022‰ at 893 AD,an inverted slope of 0.144‰ at 1855 AD,and a slope of 0.075‰ recently.These findings indicate that the modern YRD is far from being abandoned in the future,providing a historical geomorphological basis for the management of the Yellow River Estuary.
基金Supported by the Innovation Project of the Chinese Academy of Sciences (KZCX2-YW-Q1-01, XDA05080100)National Basic Research and Development (973) Program of China (2010CB950100)+1 种基金National Science and Technology Support Program of China (2007BAC03A01)National Natural Science Foundation of China (41071029)
文摘The spatial patterns of precipitation anomalies during five 30-yr warm periods of 691-720, 1231-1260, 1741-1770, 1921-1950, and 1981-2000 were investigated using a dryness/wetness grading dataset covering 48 stations from Chinese historical documents and 22 precipitation proxy series from natural archives. It was found that the North China Plain （approximately 35^-40~N, east of 105~E） was dry in four warm periods within the centennial warm epochs of 600-750, the Medieval Warm Period （about 900-1300） and after 1900. A wet condition prevailed over most of China during 1741-1770, a 30-yr warm peak that occurred during the Little Ice Age （about 1650-1850）. The spatial pattern of the precipitation anomaly in 1981-2000 over East China （25^-40~N, east of 105~E） is roughly consistent with that in 1231 1260, but a difference in the precipitation anomaly appeared over the Tibetan Plateau. The spatial patterns of the precipitation anomalies over China varied between all five 30-yr warm periods, which implies that the matching pattern between temperature and precipitation change is multiform, and the precipitation anomaly could be positive or negative when a decadal warm climate occurs in different climate epochs. This result may provide a primary reference for the mechanism detection and climate simulation of the precipitation anomaly of the future warm climate.
基金This study was supported by the Key Project from the National Natural Science Foundation of China(Grant No.40331013)the project from the Chinese Academy of Sciences(Grant No.KZCX3-SW-321).
文摘The precipitation at 17 stations over the middle and lower reaches of the Yellow River is reconstructed during the period of 1736―1910, using the snow and rainfall records in the Qing Dynasty, together with the instrumental observation data of precipitation and farmland soil moisture content. The soil physics model related to rainfall infiltration and the surface water bal-ance equation are taken as main reconstruction methodology. The field infiltration experiment by artificial rainfall is conducted to check the reliability. And the precipitation series over the middle and lower reaches of the Yellow River and its 4 sub-regions are established, going back to 1736. Analysis of the time series indicates that the abrupt change of precipitation from high to low oc-curs around 1915 over the middle and lower reaches of the Yellow River. During the three peri-ods of 1791―1805, 1816―1830 and 1886―1895, the precipitation is markedly higher than the mean of the series. While both the periods of 1916―1945 and 1981―2000 are characterized by less precipitation. Three periodicities of 22―25a, 3.9a and 2.7a are shown in the precipitation fluctuation over the middle and lower reaches of the Yellow River. Moreover, the periodical signal of 22―25a becomes weaker and weaker since the abrupt change of 1915 and disappears in the late 1940s, and then the periodical signal of 35―40a appears instead.
基金Supported by the National Natural Science Foundation of China (Grant No. 40331010)
文摘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 recon- struction 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, tem- perature variations for the last 1000 years are examined, with special focus placed on the characteris- tics of the Medieval Warm Period (MWP), the Little Ice Age (LIA), and Modern Warming (MW).
基金Basic Research Project of the Ministry of Science and Technology,No.2011FY120300The "Strategic Priority Research Program" of the Chinese Academy of Sciences,No.XDA05080100Research Project from NSFC,No.41430528
文摘China is distinguished by a prominent monsoonal climate in the east of the country, a continental arid climate in the northwest and a highland cold climate on the Qinghai-Tibet Plateau. Because of the long history of Chinese civilization, there are abundant and well-dated documentary records for climate variation over the whole of the country as well as many natural archives（e.g., tree-rings, ice cores, stalagmites, varved lake sediments and corals） that enable high-resolution paleoclimatic reconstruction. In this paper, we review recent advances in the reconstruction of climate and extreme events over the last 2000 years in China. In the last 10 years, many new reconstructions, based on multi-proxies with wide spatial coverage, have been published in China. These reconstructions enable us to understand the characteristics of climate change across the country as well as the uncertainties of regional reconstructions. Synthesized reconstructed temperature results show that warm intervals over the last 2000 years occurred in AD 1–200, AD 551–760, AD 951–1320, and after AD 1921, and also show that cold intervals were in AD 201–350, AD 441–530, AD 781–950, and AD 1321–1920. Extreme cold winters, seen between 1500 and 1900, were more frequent than those after 1950. The intensity of regional heat waves, in the context of recent global warming, may not in fact exceed natural climate variability seen over the last 2000 years. In the eastern monsoonal region of China, decadal, multi-decadal and centennial oscillations are seen in rainfall variability. While the ensemble mean for drought/flood spatial patterns across all cold periods shows a meridional distribution, there is a tri-pole pattern with respect to droughts south of 25°N, floods between 25° and 30°N, and droughts north of 30°N for all warm periods. Data show that extreme drought events were most frequent in the periods AD 301–400, AD 751–800, AD 1051–1150, AD 1501–1550, and AD 1601–1650, while extreme flood events were frequent in the periods AD 101–150, AD 251–300, AD 951–1000, AD 1701–1750, AD 1801–1850, and AD 1901–1950. Between AD 1551–1600, extreme droughts and flood events occurred frequently. In arid northwest China, climate was characterized by dry conditions in AD 1000–1350, wet conditions in AD 1500–1850, and has tended to be wet over recent decades. On the northeastern Qinghai-Tibet Plateau, centennial-scale oscillations in precipitation have occurred over the last 1000 years, interrupted by several multidecadal-scale severe drought events. Of these, the most severe were in the 1480 s and 1710 s. In southwest China, extreme droughts as severe as those seen in Sichuan and Chongqing in 2006 are known to have occurred during historical times.
基金Supported by the Project (No. 2001BA611B-01) from the Ministry of Science and Technology of China.
文摘The total 15 severe droughts are discovered with the aid of the 'RetrievalSystem of Chinese Historical Climate Records' for the last 1000 years. The droughts are extensive toenvelope more than 4 provinces and persistent to cover 3 yr or more, and their severity isequivalent to or in excess of that in the 1930s in China. According to the documentary records andrestorations it can be inferred that most droughts are more severe than those in the last 50 years.The 15 droughts may either occur warm or in a cold climate background, with 11 of the 15 cases inthe cold phase. This indicates the difference in climate correspondence between China and northernAmerica, showing the severity of the events in China to be in a cold instead of a warm climatesituation. That is likely to relate to the monsoon climate in eastern Asia.
基金National Natural Science Foundation of China, No.41371201, No.41430528 Project of Global Change No.2010CB950103
文摘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 km^2, 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.
文摘Objective: To study the effects of starting antiretroviral treatment (ART) prior the age of two years on the growth (height and weight) of HIV-infected children. Methodology: This was a retrospective cohort study. HIV-infected children on ART aged less than 15 years were divided into two groups Group 1 (G1) comprising children who started ART prior 2 years and Group (G2) those put on treatment thereafter. Main Measures: Percentage of children with growth retardation measured by Height for Age (H/A) and Weight for Age (W/A) Results: In total, we included 90 subjects. The median age was 10 years with a slight female predominance (51.2%). Most children were asymptomatic at the time of the study (96.6%), compliant with treatment (81%), 54.8% of children were on cotrimoxazole, 33% knew their status. At initiation, underweight was predominant in group 1 compared to group 2 (52% versus 29.5%;p = 0.015). Conversely, stunted growth predominated in G2 compared to G1 but without significant difference (38% versus 50%;p = 0.147). At the time of our study (median age of 10 years), catch-up height and weight predominated in G1 compared to G2;only a small proportion remained below −2SD (4% versus 18.2%;p = 0.015 and 9% versus 29.5%;p = 0.006 respectively for underweight and stunted growth). Conclusion and Global Health Implications: Growth retardation was common at ART initiation. Catch-up in height was more evident in the early treatment group. Initiation of ART before the age of 2 years rather influences children’s height than weight. The result of this study further emphasizes the need of early ART and closed clinical monitoring to better assess the impact of ART in areas with high rates of undernutrition.
文摘In 1993,the World Bank released a global report on the efficacy of health promotion,introducing the disability-adjusted life years(DALY)as a novel indicator.The DALY,a composite metric incorporating temporal and qualitative data,is grounded in preferences regarding disability status.This review delineates the algorithm used to calculate the value of the proposed DALY synthetic indicator and elucidates key methodological challenges associated with its application.In contrast to the quality-adjusted life years approach,derived from multi-attribute utility theory,the DALY stands as an independent synthetic indicator that adopts the assumptions of the Time Trade Off utility technique to define Disability Weights.Claiming to rely on no mathematical or economic theory,DALY users appear to have exempted themselves from verifying whether this indicator meets the classical properties required of all indicators,notably content validity,reliability,specificity,and sensitivity.The DALY concept emerged primarily to facilitate comparisons of the health impacts of various diseases globally within the framework of the Global Burden of Disease initiative,leading to numerous publications in international literature.Despite widespread adoption,the DALY synthetic indicator has prompted significant methodological concerns since its inception,manifesting in inconsistent and non-reproducible results.Given the substantial diffusion of the DALY indicator and its critical role in health impact assessments,a reassessment is warranted.This reconsideration is imperative for enhancing the robustness and reliability of public health decisionmaking processes.
文摘Background: This study assessed the effect of a nutrition education intervention. This intervention aimed to improve the knowledge, attitudes, and practices of mothers on food safety in the peri-urban areas of Bobo-Dioulasso in Burkina Faso. Methods: A total of 243 mothers of children under 5 years in the peri-urban of Bobo-Dioulasso were administered the FAO questionnaire for food safety knowledge, attitudes, and practices assessment during two cross-sectional surveys, before and after the intervention, in January and October 2017. The intervention included two components consisting of a theoretical phase (counselling and discussion) and cooking demonstrations implemented for ten months. To account for the before-and-after design of the study, the McNemar’s test was used to assess the effect of the intervention on food safety KAP of mothers of children under 5 years. Results: The mean age of mothers was 29 ± 6.2 years and 50.6% of them were between 20 and 29 years old. One for knowledge (cooking thoroughly with, p-value = 0.0001) and another for attitudes (perceived benefits of reheating leftovers before eating them, p-value = 0.0001), significantly increased after the intervention. In terms of food safety practices, all the indicators (cleaning of dirty surfaces, plates and utensils and storage of perishable foods) significantly increased (all p = 0.0001 Conclusion: This study provided some evidence of an effective nutrition education intervention for improving maternal KAP on food safety for their child’s feeding.
基金The National Natural Science Foundation of China under contract Nos 41376075 and 41576061
文摘Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change,especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which the reconstruction of the historical development of mangrove forests using an effective indicator has been regarded as a necessary strategy for designing a predictable model. As the primary product of mangrove forest, it is reasonable that the content of leaf fragments of mangrove(CLFM) buried in sediments in the form of sub-fossils potentially has the same indicative function for the development of mangrove forests as that of widely-used mangrove pollen. In this study, the leaf fragments of mangrove in two sediment cores(YLW02 and YLW03) drilled in the Yingluo Bay in Guangxi, Southwest China were picked out and weighted for calculation of CLFM, which was used as an indicator of mangrove development after examination of parallelism and a statistical correlation of the CLFM with the concentration of mangrove pollen. The results clearly show that the vertical distribution of the CLFM for the core taken from the landward margin of mangrove forests(YLW03) only parallels that of the local mangrove species(Rhizophora. stylosa) with a significantly positive correlation(R=0.56, P=0.05), while the vertical distribution of the CLFM for the core taken from the interface between seaward margin of mangrove forest and the trunk of tidal creeks of the bay(YLW02) parallels the summed concentration of mangrove pollen(SCMP) with a more positive correlation than that of YLW03(R=0.85, P=0.01), indicating that the trunk outlet of tidal creeks must have been the site where mangrove production gathered from the overall forest rather than from local production. The variations in the CLFM of both cores indicate that overall the mangrove forests in the Yingluo Bay have increasingly flourished over the last 130 years except for the interval of 1940–1950 AD in response to an increase in air temperature and decrease in rainfall, which would have resulted in an increase in seawater salinity;while the coupled extreme increases in air temperature and in rainfall in summer, which would have resulted in extreme decreases in seawater salinity, would be responsible for the relative degradation of mangrove forests in the interval of 1940–1950 AD.
文摘By summarizing the results of debris flow studies in China and integating with the knowledge and experience gained by the authors in their research work, thes paper makes a review and outlook on debris flow studies in China in the last 30 years. Corresponding opinions and suggestions are proposed in view of the circumstances and disasters in China.
基金supported by Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-Q1-01)China Global Change Research Program (Grant No. 2010CB950101)+1 种基金National Natural Science Foundation of China (Grant No. 40625002)the IGSNRR Research Foundation (Grant No. 200905006)
文摘Using 24 proxy temperature series, the rates of temperature change in China are analyzed at the 30- to 100-year scales for the past 2000 years and at the 10-year scale for the past 500 years. The results show that, at the 100-year scale, the warming rate for the whole of China in the 20th century was only 0.6±1.6℃/100 a （interval at the 95% confidence level, which is used here- after）, while the peak warming rate for the period from the Little Ice Age （LIA） to the 20th century reached 1.1_＋1.2~C/100 a, which was the greatest in the past 500 years and probably the past 2000 years. At the 30-year scale, warming in the 20th century was quite notable, but the peak rate was still less than rates for previous periods, such as the rapid warming from the LIA to the 20th century and from the 270s-290s to 300s-320s. At the 10-year scale, the warming in the late 20th century was very evident, but it might not be unusual in the context of warming over the past 500 years. The exact timing, duration and magnitude of the warming peaks varied from region to region at all scales. The peak rates of the 100-year scale warming in the AD 180s-350s in northeastern China as well as those in the 260s-410s and 500s-660s in Tibet were all greater than those from the mid-19th to 20th century. Meanwhile, the rates of the most rapid cooling at scales of 30 to 100 years in the LIA were promi-nent, but they were also not unprecedented in the last 2000 years. At the 10-year scale, for the whole of China, the most rapid decadal cooling in the 20th century was from the 1940s to 1950s with a rate of -0.3±0.6℃/10 a, which was similar to rates for periods before the 20th century. For all regions, the rates of most rapid cooling in the 20th century were all less than those for previous periods.
基金supported by grants to IGSNRR from China Global Change Research Program of MOST (Grant No. 2010CB950101)the Chinese Academy of Sciences (Grant No. XDA05080100)National Natural Science Foundation of China (Grant No. 41071029)
文摘The general characteristics of climate changes over the past 2000 years in China,regional differences and uncertainties were analyzed based on the recently peer-reviewed high time-resolution climatic reconstructions.The results showed that there exists four warm periods of the temperature variation in China since the Qin Dynasty,including the western and eastern Han Dynasties(200 BC-AD 180),the Sui and Tang dynasties(541-810),the Song and Yuan dynasties(931-1320),and the 20th century,and three cold phases involving the Wei,Jin,and North-South Dynasties(181-540),the late Tang Dynasty(811-930),and the Ming and Qing dynasties(1321-1920).The Song and Yuan warm period is consistent with the Medieval Warm Period over the Northern Hemisphere,and the cold phases of the North-South Dynasties and the Ming and Qing dynasties are paralleled to the Dark Ages Cold Period and the Little Ice Age,respectively.The 13th-15th century could be a shift to the wet condition of the climate,and the low precipitation variability is exhibited in western China prior to 1500.In the context of the climate warming,the pattern of the drought in north and flood in south is prevalent over the eastern China.In addition,the published reconstructions have a high level of confidence for the past 500 years,but large uncertainties exist prior to the 16th century.
