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Hydroclimate variations over eastern China are affected by the Asian monsoon, exhibiting great variability and frequent extreme events occurrence. However, the driving mechanisms of their spatial and temporal variabilities are not fully understood due to the short period of available climate observation data. Here we used interpolated dry/wet grades dataset derived from Chinese historical documents and method of regional division to reconstruct a new annual hydroclimatic variation dataset dating back 1000 years, including nine regions of eastern China. This dataset reveals the spatial coverage and trend of long‐lasting extreme drought and flood events, and discloses the spatial patterns and similarities of interannual (2–7‐year) and interdecadal (15–35‐year) hydroclimate variations under the different temperature backgrounds of the Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and Current Warm Period. Although no obvious drying or wetting trends were detected in the past 1000 years, the frequencies of extreme flood and drought events during the two warm periods of 960–1300 and 1901–2000 were higher than those during the cold period of 1301–1900. There are 17 long‐lasting and even severe than 1637–1641 large spatial scale extreme drought events during the past 1000 years. The observed spatial dipole pattern of flooding in the south and drought in the north, or the opposite pattern, was rare during the historical period. However, it was the second leading mode explaining the low variances in the principal component analysis for 2–7‐year hydroclimatic variations, which were not related to temperature change. Moreover, the stability of the teleconnection between the hydroclimate over eastern China and the climatic modes of Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation was further discussed. [ABSTRACT FROM AUTHOR]

Climate change has a significant impact on agrometeorological conditions. We analysed the winter wheat overwintering indices for the northern winter wheat production areas of China (NWPA), which include the percentage of extreme low‐temperature (daily minimum temperature ≤−22 °C) years, the first day of the overwintering period (FDO), sowing date (SD) and precipitation before winter (PBW). Then, we compared the differences of the four indices between the forecast period 2021–2050 and the baseline period 1961–1990 under the RCP4.5 scenario, which were based on the 0.5° × 0.5° grid daily meteorological data output provided by the Inter‐Sectoral Impact Model Intercomparison Project. The results showed that the occurrence of extreme cold winters decreases the NWPA, which will result in the northern boundary of winter wheat moving north by 1–2 latitudes and in an increase in the potentially safe overwintering areas by 8.5%. The FDO will be delayed in 2021–2050 by an average of 7.7 days. Climate warming will change the meteorological conditions for winter wheat overwintering in the Huang‐Huai winter wheat area, especially near the southern boundary of the winter wheat planting area, and the areas and years with no obvious overwintering periods will experience an increase by 50% and 56%, respectively. The SD will be postponed by 8.6–9.0 days. The PBW will decrease as the accumulated temperature increases, especially in the Huang‐Huai winter wheat area. In the future, the possible northern boundary for winter wheat planting may move northward, and the northernmost tip may reach 46°N. South of the Huang‐Huai region, winter wheat planting may change from a semi‐winter to a spring variety. These findings will provide a reference for generating wheat planting and management strategies in China. Climate change has significantly influenced the winter wheat planting in northern China. In 2021–2050, climate warming would decrease the occurrence of extreme cold winters in the regions near northern planting boundary, which would result in the possible northern boundary (red and green lines) moving northward, and the northernmost tip may reach 46°N. However, south of the Huang‐Huai region (black oval areas), wheat planting may change from a semi‐winter to a spring variety due to temperature increase and precipitation reduction. [ABSTRACT FROM AUTHOR]

The spatial patterns of precipitation anomalies in eastern China during both warm and cold periods over the past 2000 years were studied. Four warm periods (AD 650-750, AD 1000-1100, AD 1190-1290, and AD 1900-2000) and five cold periods (AD 440-540, AD 780-920, AD 1390-1460, AD 1600-1700, and AD 1800-1900) were selected on a centennial timescale, referring to the synthesized temperature changes over China and Northern Hemisphere. The regional differences in precipitation were analysed and compared using a data set consisting of the grades in severity of floods and droughts as derived from Chinese historical documents. The results showed that there has been no fixed spatial pattern of precipitation anomalies during either cold or warm periods in eastern China over the past 2000 years. For the most of warm periods, there existed coherence of spatial pattern with dry condition only occurred over north of the Yangtze River, and the consistent spatial patterns were found between the periods 650-750 and 1190-1290, 650-750, and 1000-1100. For the cold periods, the precipitation showed various spatial patterns, and similarities were only presented in the two periods of 1600-1700 and 1800-1900 featured by meridional distribution. Comparing the spatial patterns between cold and warm periods, inverse pattern of 440-540 and 1900-2000 over the most study area can be detected, but similar pattern was also found between the periods 1800-1900 and 1900-2000, and 1600-1700 and 1900-2000. Our results implicated that the relationship between temperature and spatial pattern of precipitation anomaly has high complexity, which would be of significance to understanding the spatial pattern of precipitation in the future climate change study. [ABSTRACT FROM AUTHOR]

Lateral movement of soil organic carbon (SOC) induced by soil erosion and runoff changes spatial distributions of SOC, and further changes the land‐atmosphere CO2 exchange and terrestrial carbon budget. However, current ecosystem models do not or only poorly integrate the process of SOC lateral movement and cannot simulate the impacts of soil erosion on the carbon cycle. This study integrated SOC erosion and deposition processes into a process‐based ecosystem model (i.e., Integrated BIosphere Simulator (IBIS)), and separately simulated the lateral movements of dissolved organic carbon (DOC) and particulate organic carbon (POC). The model was evaluated in three river basins in Northeast China that are dominated by cropland, forest, and grassland. The results showed that the model reproduced well the production, erosion, and deposition of DOC and POC. The annual SOC lateral movement (1.34–7.22 g C m−2 yr−1) induced by erosion in the three tested basins was 0.27%–1.45% of the annual net primary production. The model developed in this study has great implications for simulating the lateral movements of SOC in terrestrial ecosystems, which can improve model performance in projecting the terrestrial carbon budget. Plain Language Summary: Lateral movement of soil organic carbon (SOC) with soil erosion and runoff is an important process in estimating land carbon budget. However, the current ecosystem models are not or poorly integrated this process, and cannot simulate the impacts of lateral movement of SOC on carbon cycle. This study integrates SOC erosion and deposition processes into a process‐based ecosystem model (Integrated BIosphere Simulator (IBIS)), and separately simulates the lateral movements of dissolved organic carbon (DOC) and particulate organic carbon (POC). The model was evaluated at three river basins in Northeast China dominated by cropland, forest and grassland, respectively. The results showed the model can reproduce well the production, erosion, deposition of DOC and POC. The model developed in this study has great implications for simulating the lateral movements of SOC in terrestrial ecosystem, which can improve model performance on projecting terrestrial carbon budget. Key Points: Current ecosystem models inadequately depict the lateral movement of SOC, causing uncertainties in terrestrial carbon cycle modelingWe integrated SOC erosion and deposition into a process‐based ecosystem model and evaluated it in three Chinese river basinsModel simulations well represented observed data for the production, erosion, and deposition of organic carbon [ABSTRACT FROM AUTHOR]

This study discusses the interannual variation of spring precipitation in Northeast China (NECSP) from 1980 to 2016 and its relationship with Arctic sea ice based on observation data and numerical experiments. The observed results reveal that the leading mode of NECSP mainly exhibits a homogenous pattern with a significant interannual variation. The NECSP has a significant negative correlation with the preceding winter Barents Sea ice concentration (BSIC) at the interannual scale. In the preceding winter, the decreased BSIC resulted in positive geopotential height anomalies over the polar region, which could weaken the polar vortex and westerly winds, forming a cyclonic anomaly indirectly over West Siberia. The circulation anomalies resulted in a zonal dipole pattern of preceding winter snow water equivalent (SWE) anomalies in the mid‐high latitudes of Eurasia with less SWE over Eastern Europe and more SWE over West Siberia. The SWE anomalies in winter could persist to the subsequent spring and facilitate more precipitation over Northeast China (NEC) by local thermal processes affecting circulation anomalies over Eurasia. On the other hand, the negative preceding winter BSIC anomalies can persist to spring, increasing the NECSP by strengthening the cyclonic anomalies over NEC. In this study, the response of the atmosphere to the thermal effect of SWE is further verified by using the linear baroclinic model (LBM). The response of NECSP to BSIC loss is tested by using the Community Atmosphere Model version 5.3 (CAM5.3). [ABSTRACT FROM AUTHOR]

Zheng, J., Ding, L., Hao, Z. & Ge, Q. 2012 (January): Extreme cold winter events in southern China during AD 1650-2000. Boreas, Vol. 41, pp. 1-12. 10.1111/j.1502-3885.2011.00225.x. ISSN 0300-9483. We defined extreme cold winter events as those with occurrence probabilities lower than the 10th percentile of the probability density function, based on observed winter temperatures in southern China since 1951. Subsequently, we constructed impact severity levels using documentary evidence for those events during 1951-2000, considering three indexes for the freezing of rivers/lakes, widespread snow/ice storms, and cold damage to subtropical/tropical crops. Using these criteria we identified 50 extreme cold winters for the period AD 1650-1949 based on ∼4000 pieces of comparable information extracted from local gazettes in southern China, after verification using data from three weather stations with long records. It was found that the frequencies of the extreme cold winter events since 1650 varied over time. The most frequent occurrences were found during AD 1650-1699 and in the first and second halves of the 19th century, with frequencies twice as high as in the second half of the 20th century. In contrast, the frequencies of extreme winters during the 18th century were close to that in the second half of the 20th century. High frequencies of extreme cold winters in AD 1650-1720 and AD 1795-1835 occurred during the sunspot Maunder and Dalton Minima. The intensities of some historical cold events, such as those during 1653-1654, 1670, 1690, 1861, 1892 and 1929, exceeded those of the coldest winter events since 1951. [ABSTRACT FROM AUTHOR]

Technological advances have the potential to balance climate change mitigation and economic development. However, it remains unclear how much technological advances alone can mitigate climate change and the associated economic losses in the future. Through designing a suite of technological advances scenarios and using an earth system model with an integrated assessment model, we illustrate that rapid technological progress without production control might achieve the 2°C global warming target in the 2100s. Relative to a world of stagnant technology, the frequency (intensity) of extreme warm events at the end of the 21st century (2081–2100) would be reduced by ∼21% (5.5°C) via rapid technological advances, with a reduction in extreme precipitation (droughts) by ∼41% (10 times). Furthermore, fast technological advances may reduce the global economic losses linked with climate change at 2081–2100 by ∼21% and those in China related to floods (droughts) by 86% (67%). Our results highlight the potential of technological advances to fill the emission gap between the Paris Agreement and unconditional Nationally Determined Contributions and hence to efficiently mitigate global warming. [ABSTRACT FROM AUTHOR]

Modern meteorological observations in South China from 1960 to 2009 show a strong correlation between winter temperatures and two snowfall parameters, the southern boundary of the snow and the number of snowy days. Based on this relationship, the variation in annual winter mean temperature in South China from 1736 to 2009 was reconstructed using data acquired from Chinese historical documents dating from the Qing dynasty, such as memos and local gazettes. The reconstructed time series were used to analyse variations in winter temperature in South China. Significant interannual and interdecadal changes were found. The maximum temperature difference between neighbouring years was 3.1 °C for 1958-2009 and 3.0 °C for 1736-1957, whereas the maximum temperature difference between adjacent decades was 0.8 °C for the 1960s-2000s and 0.6 °C for the 1740s-1950s. The 2000s was the warmest decade; the mean temperature was 1.6 °C higher than that of the 1870s, which was the coldest decade between the 1740s and the 2000s. The mean winter temperature was warmer in the 18th and 20th centuries and coldest in the 19th century. [ABSTRACT FROM AUTHOR]