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This paper deals with climate change and nomadic migration relationships at a long-term and wide geographical scale using a statistical approach in the vein of Bai and Kung (Rev Econ Stat 93:970–981 2011). More precisely, it presents a reassessment of these relationships in a nonlinear world using threshold regressions, time varying-copula, and nonlinear causality tests. The large amount of historical records in China enables us to re-interpret the link between climate and historical social dynamics (Hsiang et al., Science 341:1235367 2013) through different regimes of temperature and precipitation. Our nonlinear results have confirmed the role of climatic factors on migration. However, we find that climatic factors have affected the migration flows only during some sub-periods (especially 300–500 AD and 1050–1300 AD). As a consequence, the importance of the precipitation effect on migration has probably been slightly overestimated whereas the role of temperature anomalies has been underestimated. [ABSTRACT FROM AUTHOR]

The current nationally determined contributions, pledged by the countries under the Paris Agreement, are far from limiting climate change to below 2 ∘C temperature increase by the end of the century. The necessary ratcheting up of climate policy is projected to come with a wide array of additional benefits, in particular a reduction of today's 4.5 million annual premature deaths due to poor air quality. This paper therefore addresses the question how climate policy and air pollution–related health impacts interplay until 2050 by developing a comprehensive global modeling framework along the cause and effect chain of air pollution–induced social costs. We find that ratcheting up climate policy to a 2 ∘ compliant pathway results in welfare benefits through reduced air pollution that are larger than mitigation costs, even with avoided climate change damages neglected. The regional analysis demonstrates that the 2 ∘C pathway is therefore, from a social cost perspective, a "no-regret option" in the global aggregate, but in particular for China and India due to high air quality benefits, and also for developed regions due to net negative mitigation costs. Energy and resource exporting regions, on the other hand, face higher mitigation cost than benefits. Our analysis further shows that the result of higher health benefits than mitigation costs is robust across various air pollution control scenarios. However, although climate mitigation results in substantial air pollution emission reductions overall, we find significant remaining emissions in the transport and industry sectors even in a 2 ∘C world. We therefore call for further research in how to optimally exploit climate policy and air pollution control, deriving climate change mitigation pathways that maximize co-benefits. [ABSTRACT FROM AUTHOR]

Using case study analysis across three sectors in China (cement, electric vehicles and coal fired electricity generation) and theoretical insights from the innovation studies literature, this paper analyses the development of China's technological capabilities in low carbon technologies and the ways in which public policies have contributed to developing these capabilities. It finds that China has developed significant capabilities via a strategic approach. The paper's findings have significant implications for international policies designed to support low carbon technology transfer to developing countries and broader processes of low carbon technological change and development. Such policies should go beyond the traditional focus on the transfer of technology hardware to focus on the development of low carbon technological capabilities in developing country firms. [ABSTRACT FROM AUTHOR]

Farmers' perceptions of the local climate reflect their own judgments of climate change and may thus affect their adaptation behavior. However, the mechanisms between the provision of early warning information and farmers' perceptions and adaptation behavior are under-researched. To address this gap in the literature, this study uses original household survey data from nine provinces in China to examine the major factors influencing farmers' perceptions of drought and examines how perceptions affect adaptation behavior. The results show that over half of the sample farmers perceived that drought severity had increased during the past 10 years. Moreover, econometric analysis indicates that about 8% more farmers will adopt surface pipes in response to drought if early warning information about drought is provided. Farmers that perceived increasing drought severity are more likely to attempt to adapt by adopting water-saving technologies. The paper concludes by offering some policy implications for the presented results. [ABSTRACT FROM AUTHOR]

China is the largest wheat-producing country in the world. Wheat is one of the two major staple cereals consumed in the country and about 60% of Chinese population eats the grain daily. To safeguard the production of this important crop, about 85% of wheat areas in the country are under irrigation or high rainfall conditions. However, wheat production in the future will be challenged by the increasing occurrence and magnitude of adverse and extreme weather events. In this paper, we present an analysis that combines outputs from a wide range of General Circulation Models (GCMs) with observational data to produce more detailed projections of local climate suitable for assessing the impact of increasing heat stress events on wheat yield. We run the assessment at 36 representative sites in China using the crop growth model CSM-CropSim Wheat of DSSAT 4.5. The simulations based on historical data show that this model is suitable for quantifying yield damages caused by heat stress. In comparison with the observations of baseline 1996-2005, our simulations for the future indicate that by 2100 the projected increases in heat stress would lead to an ensemble-mean yield reduction of −7.1% (with a probability of 80%) and −17.5% (with a probability of 96%) for winter wheat and spring wheat, respectively, under the irrigated condition. Although such losses can be fully compensated by CO fertilization effect as parameterized in DSSAT 4.5, a great caution is needed in interpreting this fertilization effect because existing crop dynamic models are unable to incorporate the effect of CO acclimation (the growth-enhancing effect decreases over time) and other offsetting forces. [ABSTRACT FROM AUTHOR]

China has a large economic and demographic exposure to extreme events that is increasing rapidly due to its fast development, and climate change may further aggravate the situation. This paper investigates China's socioeconomic risk from extreme events under climate change over the next few decades with a focus on sub-national heterogeneity. The empirical relationships between socioeconomic damages and their determinants are identified using a hierarchical Bayesian approach, and are used to estimate future damages as well as associated uncertainty bounds given specified climate and development scenarios. Considering projected changes in exposure, we find that the southwest and central regions and Hainan Island of China are likely to have a larger percentage of population at risk, while most of the southwest and central regions could generally have higher economic losses. Finally, the analysis suggests that increasing income can significantly decrease the number of people affected by extremes. [ABSTRACT FROM AUTHOR]

This paper studies the interplay between climate, health, and the economy in a stylized world with eleven heterogeneous regions, with special emphasis on USA, Europe, China, India, and Africa. We introduce health impacts into a simple economic integrated assessment model where both the local cooling effect of S O and the global warming effect of C O are endogenous, and investigate how these factors affect the equilibrium path. Regions do not respond in the same way to climate change. In particular, emission abatement rates and health costs depend on the economic and geographical characteristics of each region. Two policy scenarios are considered, Nash and Optimal, for which we present both global and regional results. Results for Africa and China are highlighted. [ABSTRACT FROM AUTHOR]

Climate change has substantial impacts on regional hydrology in the major river basins. To figure out such latent hydrological impacts of changing climate, more reliable hydrological simulations are imperative. In this study, we evaluated the impacts of climate change on hydrological regime in the Upper Yangtze River Basin based on four downscaled and bias-corrected Global Climate Model outputs from Coupled Model Intercomparison Project Phase 5 under four Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) driving three hydrological models. Two model evaluation approaches were applied: simple and comprehensive. The comprehensive approach was used to evaluate models in the historical period, optimizing objective function at four gauges, and hydrological models were weighted for impact assessment based on their performance. In such a way, projected streamflow time series are obtained under different emission scenarios. Results show that the annual average discharge is projected to increase by 4.1–10.5% under the RCP scenarios at the end of twenty-first century relative to the reference period (1970–1999). Moreover, the high flow is projected to increase and the low flow to decrease indicating a higher probability of flood and drought occurrence in the basin. The severity of floods and droughts may increase. In comparison with the simple one-site model evaluation approach, the comprehensive method reveals that the anticipated extreme flow events would be less severe, and annual mean discharge slightly lower. The projected results imply that application of the comprehensive model evaluation approach could narrow the simulated spreads of projections significantly, and might provide more credible results. [ABSTRACT FROM AUTHOR]

Drought, which negatively affects crop yields, is expected to intensify in the future and will continue to threaten food security. Understanding crop yield responses to drought is essential for seeking more effective strategic adaptations and for reducing the risk of yield failure. However, how to regionally quantify drought-induced yield loss rates remains unclear. We addressed this gap through studying summer maize cultivated in the Huang-Huai-Hai farming region of China during 1981–2010. By incorporating yearly phenological data and dividing the growing season into the vegetative stage and reproductive stage, we used the standardized precipitation evapotranspiration index (SPEI) that is specific to different growth stages to reflect drought conditions. The spatial-temporal characteristics of drought conditions were further depicted, and the drought-induced yield loss rate was analyzed. The results showed that drought was unevenly and spatially distributed throughout the whole region, and extreme drought mostly occurred in the northern and northwestern regions even though they have a lower drought frequency. However, the drought tendency was alleviated across the maize growing season since the accumulated precipitation and average daily maximum temperature together determined the direction of drought severity. The drought-induced yield loss rate is related to both the intensification of extreme drought and the local precipitation conditions. These findings highlight the potential incentive of the drought-induced yield loss rate, and emphasize that innovation on farming activity is urgently needed to enhance maize productivity in regions with overexploited groundwater. [ABSTRACT FROM AUTHOR]

Landslides result in a significant number of casualties every year in China. The frequency and intensity of extreme precipitation are expected to increase due to climate change, leading to a change in landslide occurrence. This study focuses on climate change impacts on event rainfall characteristics that are commonly linked to landslide occurrence in China. A modelling framework was proposed to quantitatively assess the spatiotemporal change in event rainfall characteristics influencing landslide occurrences in China under future scenarios. First, an algorithm was used to extract the rainfall events from observed precipitation data and the 21 Global Circulation Models dataset. Then, the cumulative event rainfall-rainfall duration (E-D) threshold was identified and used as a proxy of landslide occurrence. Finally, the historical (1971–2000) and future (2031–2060 and 2066–2095) data of 21 GCMs were then applied to determine the E-D threshold in areas highly susceptible to landslides in China to assess the impact of climate change. Landslide occurrence is projected to increase potentially under all GCMs, by amounts ranging from 19.9% to 33.2% in the late 21st century compared to the historical period under the RCP4.5 and RCP85 scenarios, respectively. There are regional differences in the impact of climate change. Future landslide increases in the Northwest region and the Qinghai-Tibet region are the most significant, with consistency among multiple GCMs. However, there is only a slight increase in the South China region with high uncertainty. The monthly variations in landslides are bimodal, with the largest increases in spring and autumn. The results indicate that using a single GCM to assess climate change impacts may have biases, and consideration of median trends and variations among multiple GCMs is suggested. However, the study is a first hint on how climate change may affect landslide occurrence in the future, as the assessment of the effect of climate change on landslides is not straightforward based on only the precipitation-related proxy. The influence on air temperature and soil moisture and the selection of projection datasets and proxies should be carefully considered when applying the presented methods for climate change impacts on landslide studies. [ABSTRACT FROM AUTHOR]

There are clear signs that milk production growth is leveling off, and recently even declining, in China. Heat stress is one of the main reasons for the recent reduction in milk production. In this study, we computed the change in milk production as a result of heat stress in major milk production areas in China. We constructed a temperature–humidity index (THI) spatial layer to understand the monthly distribution of heat and moisture. We documented specific areas in northern China where cattle were at high risk to heat stress in specific months. THI values exceeded the threshold above which milk production declines during months of June, July, and August. Especially during July, the THI value was higher than the production threshold in recent years (2008 to 2016) and in projected future scenarios (2050 and 2070). THI-based milk yield losses were up from 0.7 to about 4 kg per cow per day in July 2016. These losses are projected to increase from 1.5 to 6.5 kg in 2050 and 2 to 7.2 kg in 2070 (representing production losses between 15 and 50%). These results suggest that climate change will have significant consequences for the dairy sector in major milk-producing areas in China. Our results are useful in identifying areas susceptible to heat stress where adaptive livestock management practices are needed to prevent significant production decreases. [ABSTRACT FROM AUTHOR]

Investigating oasis effects of different oasis-town configurations is key to understanding the ecological stability of the oasis. However, previous studies have not considered the impacts of oasis–town configurations on oasis effects. In this study, the Weather Research and Forecasting (WRF) model was used to conduct a series of 1-km-resolution simulations of the Hami Oasis, Xinjiang of China, to examine how different oasis–town configurations influenced the oasis effects. The actual landscape and four hypothetical landscapes were considered. Results indicated that the WRF model effectively reproduced the trends of the surface temperature, 2-m air temperature, 2-m relative humidity, and 10-m wind speed. It was also found that the effects of the town on the oasis were substantially greater when the former was located at the center of the oasis, rather than on the margin. At 850 hPa, the center of the temperature field was downstream from that of the wind field, whereas both coincided at lower levels. When the size of the town was doubled, the convergence center over the town weakened the strength of the divergent low-level winds from the oasis. This facilitated the infiltration of dry air from the surrounding desert into the oasis, which is detrimental to the healthy development of the oasis. Placing a town at the margin of the oasis is therefore advantageous to the development of the cold island, whereas a town at the center of the oasis is beneficial to the comfort of the residents. [ABSTRACT FROM AUTHOR]

A persistent concern about the social consequences of climate change is that large, vulnerable populations will be involuntarily displaced. Existing evidence suggests that changes in precipitation and temperature can increase migration in particular contexts, but the potential for this relationship to evolve over time alongside processes of adaptation and development has not been widely explored. To address this issue, we link longitudinal data from 20 thousand Chinese adults from 1989 to 2011 to external data on climate anomalies and use this linked dataset to explore how climatic effects on internal migration have changed over time while controlling for potential spatial and temporal confounders. We find that temperature anomalies initially displaced permanent migrants at the beginning of our study period, but that this effect had reversed by the end of the study period. A parallel analysis of income shares suggests that the explanation might lie in climate vulnerability shifting from agricultural to non-agricultural livelihood activities. Taken together with evidence from previous case studies, our results open the door to a potential future in which development and in situ adaptation allow climate-induced migration to decline over time, even as climate change unfolds. [ABSTRACT FROM AUTHOR]

Studies about climate change and the variation of the spatial pattern of war are extremely scarce in academia at present. Therefore, the temperature series and battle coordinates in imperial China from AD 5 to 1911 are integrated in this research, and their long-term quantitative relationship is examined by employing mathematical statistics such as one-way ANOVA, as well as the spatial analytical tool, standard deviational ellipse (SDE) in ArcGIS. Meanwhile, the temperature sequence is divided into three multicentennial warm–cold cycles, which are combined with different types of war (all war, agri-nomadic conflict, and rebellion) to reveal the spatial disparity of war under the influence of secular and periodic temperature change. Results show that (1) battle longitude and battle latitude are significantly different between warm and cold phases. (2) SDEs stretch toward the north/west/northwest in warm intervals but retreat south-/east-/southeastward in cold stages. (3) SDEs generally shift southeastward over time, and the variation of latitude is more evident than that of longitude, which corresponds to the overall cooling trend throughout the past 2000 years. Based on these research findings, we conclude that temperature fundamentally regulates the spatial difference of war in imperial China via controlling agricultural and pastoral productivity. This innovative study provides a robust climatological explanation of the historical conundrum why wars in ancient China distribute with specific directions, and it also lays a foundation for spatiotemporal investigations of climate change and human responses at long-term scales in the future. [ABSTRACT FROM AUTHOR]

Using multiple proxy data of historical hydroclimate variations, this study first selects the five heaviest megadrought decades in North China during the last millennium and then depicts the spatial pattern of hydroclimate over the Northern Hemisphere through these five megadrought decades. The results shows that abnormally dry conditions existed in East Asia, North America, and Europe when megadroughts in North China during the last millennium. The intensity of dry conditions in North America was stronger than that in Europe. Then, through comparing the spatial patterns of hydroclimate from proxy data with ensemble modeling of nine CMIP5/PMIP3 models, we find that such megadroughts in North China, and the contemporaneously abnormal dry conditions over the Northern Hemisphere were very likely mainly induced by external forcing, i.e., large volcanic eruptions and weakened solar irradiation. These external forcing may lead to climate cooling and, hence, air motion downward at mid-lower layer of troposphere, inducing a much more stable troposphere; as well as, the land-ocean pressure differences were weakened, and, hence, there would be decreased water vapor flux from ocean to land. Both of intensified stability of troposphere and weakened vapor transportations to land would lead to precipitation decline and, as a result, would be favorable for drought. It is therefore necessary to consider these external forcing into future climate change predicting to improve our ability of predicting megadrought. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau constitutes unique mountain ecosystems that can be used for early detection of the impacts of climate change on ecosystem functions. We use the MAPSS-CENTURY 2 (MC2), a dynamic global vegetation model, to examine the potential responses of terrestrial ecosystems to climate change in the past (1961–2010) and future (2011–2080) under one medium-low warming scenario (RCP4.5) at a 1-km spatial resolution in the Upper Heihe River Basin (UHRB), northwestern China. Results showed that 21.4% of the watershed area has experienced changes in potential natural vegetation types in the past and that 42.6% of the land would undergo changes by the 2070s, characterized by a sharp increase in alpine tundra at the cost of cold barren land. Net primary productivity (NPP) and heterotrophic respiration (RH) have increased sharply since the mid-1980s and are projected to remain at reduced rates in the future. Overall, UHRB switched from carbon neutral to a carbon sink in 1961–2010, and the sink strength is projected to decline after 2040. Additionally, future climate change is projected to drive a decrease in water yield due to a slight decrease in precipitation and an increase in evapotranspiration (ET). Furthermore, we find large spatial variations in simulated ecosystem dynamics, including an upward trend of NPP, RH, and ET in the alpine zone, but a downward trend in the mid-elevation forest zone. These results underscore the complexity of potential impacts of climate change on mountain watersheds that represent the headwaters of inland river systems in an arid environment. [ABSTRACT FROM AUTHOR]

Climatic variation within a typical dry-valley area located in the southern Hengduan Mountains of China is studied, and the potential regional climate influences of large reservoirs in the area are discussed. Six meteorological stations near a reservoir are identified and classified into two categories (dry and non-dry valleys) to compare their level of climate change. Temperatures tended to increase since 1990 with a precipitation shift toward the dry season in both dry and non-dry valleys. Wavelet analysis shows that temperature and precipitation have significant variation with periods of 3.6 and 16.5 years, respectively. The standardized precipitation evapotranspiration index (SPEI) shows that dry valleys have multiple drought trends. Temperature in non-dry valleys changed more than that in dry valleys, but the variations of other indices in the two categories of valleys are not statistically different. The climatic variation of one station is in accordance with the reservoir filling, which is related to the orientation of the reservoir in the prevailing wind direction especially during summer. This study provides a profile of the climate change of dry valleys and documents the influence of large artificial reservoirs on regional climate. [ABSTRACT FROM AUTHOR]

Given the severe impacts of hot summers on human and natural systems, we attempt to quantify future changes in extreme hot summer frequency in China using the Coupled Model Intercomparison Project Phase 5 (CMIP5) projections. Unlike previous studies focusing on fixed future time slices, we investigate the changes as a function of global mean temperature (GMT) rise. Analyses show that extreme hot summers (June-July-August mean temperature higher than 90 % quantile of 1971-2000 climatology) are projected to occur at least 80 % of the time across China with a GMT rise of 2 °C. The fraction of land area with extreme hot summers becoming the norm (median of future summer temperatures exceed the extreme) will increase from ~15 % with 0.5 °C of GMT rise to ~97 % with 2.5 °C GMT rise, which is much greater than for the global land surface as a whole. A distinct spatial pattern of the GMT rise threshold over which the local extreme hot summer first becomes the norm is revealed. When averaged over the country, the GMT rise threshold is 0.96 °C. Earth system models exhibit comparable results to climate system models, but with a relatively larger spread. Further analysis shows that the concurrence of hot and dry summers will increase significantly with the spatial structure of responses depending on the definition of drying. The increase of concurrent hot and dry conditions will induce potential droughts which would be more severe than those induced by only precipitation deficits. [ABSTRACT FROM AUTHOR]

China has embarked on an ambitious pathway for establishing a national carbon market in the next 5-10 years. In this study, we analyze the distributional aspects of a Chinese emissions-trading scheme from ethical, economic, and stated-preference perspectives. We focus on the role of emissions permit allocation and first show how specific equity principles can be incorporated into the design of potential allocation schemes. We then assess the economic and distributional impacts of those allocation schemes using a computable general equilibrium model with regional detail for the Chinese economy. Finally, we conduct a survey among Chinese climate-policy experts on the basis of the simulated model impacts. The survey participants indicate a relative preference for allocation schemes that put less emissions-reduction burden on the western provinces, a medium burden on the central provinces, and a high burden on the eastern provinces. Most participants show strong support for allocating emissions permits based on consumption-based emissions responsibilities. [ABSTRACT FROM AUTHOR]

The article presents a study related to integrated assessment of China's adaptive capacity to climate change. Topics discussed include effects of climate changes and temperature rises in socio-economic systems, rise in atmospheric greenhouse gas (GHG) concentrations and need of direct capital investment from China towards vulnerable areas.

Assessment of agricultural vulnerability to climate change is a prerequisite for developing effective adaptation options and strategies for the future. While assessment approaches vary across sectors and countries, there is a need to devise an effective method to assess agricultural vulnerability and provide information to policy-makers and stakeholders so that they can take appropriate adaptation actions. Agricultural vulnerability is analyzed as a function of exposure, sensitivity and adaptive capacity using a multi-indicator approach. Spatial and temporal assessment is undertaken through constructing maps of agricultural vulnerability in China. The results indicate that using multiple indicators is very practical for assessing agricultural vulnerability and that agricultural vulnerability is already significant in Guizhou, Guangxi and Yunnan provinces in China and will become more serious in the 2040s. It was also found that adaptive capacity was generally underdeveloped in poor regions, such as Guizhou, Yunnan and Gansu. We recommend that policy-makers increase investment in improving irrigation infrastructure and provide more opportunities for the education of farmers and stakeholders together with developing the economy in vulnerable areas. [ABSTRACT FROM AUTHOR]