Background Of Global Warming Research Articles

Regional and Phased Vegetation Responses to Climate Change Are Different in Southwest China

Southwestern China (SW) is simultaneously affected by the East Asian monsoon, South Asian monsoon and westerly winds, forming a complex and diverse distribution pattern of climate types, resulting in a low interpretation rate of vegetation changes by climate factors in the region. This study explored the response characteristics of vegetation to climatic factors in the whole SW and the core area of typical climate type and the phased changes in response, adopting the form of “top-down”, using linear trend method, moving average method and correlation coefficient, and based on the climate data of CRU TS v. 4.02 for the period 1982–2017 and the annual maximum, 3/4 quantile, median, 1/4 quantile, minimum and average (abbreviated as P100, P75, P50, P25, P5 and Mean) of GIMMS NDVI, which were to characterize vegetation growth conditions. Coupling with the trend and variability of climate change, we identified four major types of climate change in the SW, including the significant increase in both temperature and precipitation (T+*-P+*), the only significant increase in temperature and decrease (T+*-P−) or increase (T+*-P+) of precipitation and no significant change (NSC). We then screened out nine typical areas of climate change types (i.e., core areas (CAs)), followed by one T+*-P+* area, which was located in the center of the lake basin of the Qiangtang Plateau. The response of vegetation to climatic factors in T+*-P+* area/T+*-P+ areas and T+*-P− areas/NSC areas were mainly manifested in an increase and a significant decrease, which makes the response characteristics of vegetation to climatic factors in the whole SW have different directionality at different growth stages. Our results may provide new ideas for clearly showing the complexity and heterogeneity of the vegetation response to climate change in the region under the background of global warming.

Modulation of sea surface temperature over the North Atlantic and Indian‐Pacific warm pool on interdecadal change of summer precipitation over northwest China

AbstractUnder the background of global warming, the summer precipitation over northwest China (NW) has experienced a significant interdecadal shift since the early 1990s, followed by a great increase in precipitation. This increase was mainly due to the anomalous water vapour input from the eastern boundary, whose transport has gradually become the main moisture transport belt affecting summer precipitation over NW in the past 30 years. Further research indicates that the anomalous easterly water vapour transport mainly originates from the Arctic and North Pacific Oceans. The interdecadal increase in precipitation and changes in water vapour transport pathways are related to the interdecadal warming of the North Atlantic (NA) and Indian‐Pacific warm pool (IPWP) in the mid‐1980s. The IPWP warming potentially weakens the land–sea thermal gradient, dampens the meridional circulation in East Asia, and thereby significantly reduces the southerly water vapour transport of the Asian summer monsoon, and generates anomalous northeasterly water vapour transport from high latitudes over East Asia. Moreover, the warmer sea surface temperature (SST) over the IPWP and NA can induce an anomalous teleconnection wave train, with anomalous anticyclones over Lake Baikal and the Aleutian Islands, and an anomalous cyclone over Japan. This type of teleconnection wave train contributes to anomalous northerly winds over eastern China and easterly winds over NW. The above‐mentioned anomalous circulation favours moisture transport from both the Arctic and North Pacific toward the NW, resulting in an increase in summer precipitation associated with the anomalous regional ascending motion.

The Climate Characteristics of the Northeast China Cold Vortex against the Background of Global Warming

In this study, by using the ERA5 data of the atmospheric circulation field that was re-analyzed by the ECMWF (European Centre for Medium-Range Weather Forecasts), we revealed the features of the Northeast China Cold Vortex (NCCV) from 1950 to 2020 (including active days, occurrence time of NCCV processes, and process durations). This study focused on a comparative analysis of the differences in the NCCV’s climate characteristics in the cold and warm periods to help future predictions. The results revealed the following: From 1950 to 2020, the NCCV occurred 2961 times on 9782 days. The average annual occurrence time of NCCV processes, annual average of cold vortex days, and average process duration of the NCCVs were 41.7 times, 137.8 days, and 3.6 days, respectively. These indicators of the NCCVs showed an increasing trend, but the trend was not significant. The NCCVs occurred most frequently in May, followed by June, and were located at the southernmost point in June. Therefore, it had the most active days and a relatively long process duration in May and June, significantly impacting Northeast China. During the cold period (1950–1980), the annual occurrence time of NCCV processes, number of cold vortex days, and the process duration of the NCCVs all showed an increasing trend, while in the warm period, these showed a decreasing trend. In addition, the durations of the NCCVs decreased significantly in the warm period, which indicated that the NCCV processes continued to weaken after climate warming. During the warm period (1981–2020), the frequency and active days of the NCCVs throughout the year and most months increased, and its general location was more southerly than in the cold period. Moreover, the annual average occurrence time of NCCV processes, number of active days, and average duration of the NCCV in the warm period were more than those in the cold period. Finally, the NCCVs continued for longer in autumn and winter than in spring and summer, and the durations of the NCCVs increased in warm periods.

A millennium ENSO-related droughts and floods occurrences documented by fossil phytoliths in core sediments of Poyang Lake, East China

Droughts and floods caused by extreme hydroclimatic events in East Asian monsoon area often have serious effects on human society. The Poyang Lake region has always been one of the most severe floods and droughts in East China. In order to explore the relationship between monsoon climate change and occurrence of drought/flood, this study rebuilt a high-resolution (~10 yr) of temperature and aridity change history of the past 1000 years. Phytolith assemblages together with the climatic indices revealed 3 phases of paleoenvironmental changes over the last millennium: (1) Medieval Warm Period (MWP) during 900–1370 AD witnessed increased monsoon precipitation and frequent floods corresponding to strong El Niño–like state; (2) Little Ice Age (LIA) during 1370–1800 AD experienced severe droughts coupling with decreased monsoon precipitation and intensive La Niña–like state; (3) Current Warm Period (CWP) during 1800–2003 AD encountered highly frequent floods related to the increased monsoon precipitation modulated by strong El Niño–like state. Our results confirmed that there is a connection between solar irradiance, ENSO activity and monsoon precipitation in the subtropical East China. On interannual-decadal timescales, due to the modulation of ENSO on the location of the Western Pacific Subtropical High (WPSH) and Meiyu Belt, the occurrences of droughts and floods affected by ENSO-related monsoon precipitation has significantly affected not only the sedimentary environment, but also human activities, which is significant for the prediction of future prevention of droughts and floods in the East Asian monsoon region against the background of global warming.

Effects of ambient temperature on hospital admissions for obstructive nephropathy in Wuhan, China: A time-series analysis

Under the background of global warming, it has been confirmed that heat exposure has a huge impact on human health. The current study aimed to evaluate the effects of daily mean ambient temperature on hospital admissions for obstructive nephropathy (ON) at the population level. A total of 19,494 hospitalization cases for ON in Wuhan, China from January 1, 2015 to December 31, 2018 were extracted from a nationwide inpatient database in tertiary hospitals according to the International Classification of Diseases (ICD)− 10 codes. Daily ambient meteorological and pollution data during the same period were also collected. A quasi-Poisson Generalized Linear Model (GLM) combined with a distributed lag non-linear model (DLNM) was applied to analyze the lag-exposure-response relationship between daily mean temperature and daily hospital admissions for ON. Results showed that there were significantly positive associations between the daily mean temperature and ON hospital admissions. Relative to the minimum-risk temperature (−3.4 ℃), the risk of hospital admissions for ON at moderate hot temperature (25 ℃, 75th percentile) occurred from lag day 4 and stayed to lag day 12 (cumulative relative risk [RR] was 1.846, 95 % confidence interval [CI]: 1.135–3.005, over lag 0–12 days). Moreover, the risk of extreme hot temperature (32 ℃, 99th percentile) appeared immediately and lasted for 8 days (RR = 2.019, 95 % CI: 1.308–3.118, over lag 0–8 days). Subgroup analyses indicated that the middle-aged and elderly (≥45 years) patients might be more susceptible to the negative effects of high temperature, especially at moderate hot conditions. Our findings suggest that temperature may have a significant impact on the acute progression and onset of ON. Higher temperature is associated with increased risks of hospital admissions for ON, which indicates that early interventions should be taken in geographical settings with relatively high temperatures, particularly for the middle-aged and elderly.

A Quick Detection of Lake Area Changes and Hazard Assessment in the Qinghai–Tibet Plateau Based on GEE: A Case Study of Tuosu Lake

Under the background of global warming, lake changes in the Qinghai–Tibet Plateau and their impacts have been widely concerned. To avoid downloading and preprocessing numerous remote sensing images, we used JavaScript to preprocess the Landsat OLI and Sentinel-2 MSI images based on the Google Earth Engine (GEE) platform and extract the water area of Tuosu Lake by combining NDWI, MNDWI, and SVM methods. The area changes of Tuosu Lake in 2000–2021, and their impact on the surrounding infrastructure were further analyzed. The results show that 1) in different methods of surface water extraction, the segmentation based on NDWI is the most efficient for delineating the Tuosu Lake, and the optimal threshold is 0.15 ± 0.03. 2) During 2000–2021, the area of Tuosu Lake increased by about 45.79 km2, which can be roughly divided into a slow growth period (2000–2013, 1.20 km2/a), a stable period (2013–2016, 0.49 km2/a), slow expansion period (2016–2017, 1.97 km2/a), and rapid expansion period (2017–2021, 7.43 km2/a). In particular, in 2019–2020, the lake area increased sharply by 9.22 km2. 3) Affected by the expansion of Tuosu Lake, the highway along the northern lake had been seriously threatened, and about 19.17 km (83.28%) of it was submerged by 2021. In addition, the distance between Tuosu Lake and the Qinghai–Tibet Railway has been shortened year by year, with the shortest distance of 0.85 km in 2021.

The Impact of Agricultural Production Efficiency on Agricultural Carbon Emissions in China

With the rapid development of China’s economy, China has become the world’s largest carbon emitter. China not only has an obvious growth rate of industrial carbon emissions but also the intensity of agricultural carbon emissions is hovering at a high level. The development of China’s agricultural economy has largely come at the expense of high emissions. Currently, under the background of global warming and difficulty in controlling greenhouse gas emissions, the development of low-carbon agriculture is an important way to realize the harmonious development of the ecological environment and economic growth and to promote the sustainable development of agriculture. The agricultural production efficiency is the main factor affecting the intensity of agricultural carbon emissions. Based on provincial panel data of China from 2010 to 2019, this paper establishes an indicator system and uses the super-efficiency SBM model to measure agricultural production efficiency. The regional agricultural carbon emissions were estimated using carbon-emission-related agricultural production activities. In order to study the nonlinear relationship between agricultural production efficiency and agricultural carbon emission intensity in the narrow sense, this paper uses a threshold regression model with agricultural carbon emissions as the threshold variable. Based on the analysis of China’s agricultural production efficiency and agricultural carbon emissions from 2010 to 2019, an empirical test is conducted through a threshold regression model. The results show an “inverted U-shaped” relationship between agricultural production efficiency and agricultural carbon emission intensity. In areas with high agricultural production efficiency, the improvement of production efficiency can suppress the intensity of agricultural carbon emissions; in areas with low agricultural production efficiency, the improvement of production efficiency increases the intensity of agricultural carbon emissions. Finally, based on the research conclusions, this paper provides feasible suggestions and countermeasures for China’s agricultural carbon emission reduction and improvement of agricultural production efficiency.

Identification and Spatial-Temporal Variation Characteristics of Regional Drought Processes in China

Based on the daily temperature and precipitation data from 1961 to 2021 obtained from 2019 national meteorological stations of China, and by means of Meteorological Drought Comprehensive Index (MCI) and some improved identification methods, we identified all drought event processes in all the seven regions of China in this paper. We also carefully analyzed these regional droughts and made following conclusions: drought was spreading towards southern China with an increasing frequency; consecutive drought year group occurred in all the seven regions of China with an increasing frequency under the background of global warming; both drought duration and comprehensive intensity consistently changed with the area affected by drought, with a correlation coefficient of 0.52–0.67 and 0.88–0.99 respectively, and passed the significance test of 0.05. The method used in this paper could be employed to effectively monitor and evaluate drought processes from multiple dimensions including duration, comprehensive intensity and area affected by drought. Thus, it actually provided a helpful decision-making basis for governments to prevent the risk of drought.

Changes of the sea ice and snow cover extent associated with temperature changes in the Northern and Southern Hemispheres in recent decades

Changes in snow cover and sea ice extents associated with temperature changes in the Northern and Southern Hemispheres for the period 1979-2020 are analysed using monthly-mean satellite and reanalysis data. Quantitative estimates of the relationship between the Antarctic and Arctic sea ice and changes in the surface air temperature were obtained. Overall increase of the Antarctic sea ice extent is associated with the regional manifestation of natural multidecadal climate modes with periods of up to several decades (against the background of global warming and a rapid decrease in the extent of sea ice in the Arctic). The results of correlation and cross-wavelet analyses show significant coherence and negative correlation of the surface air temperature in both Arctic and Antarctic with the respective sea ice extent in recent decades. Seasonal and regional features of the snow cover sensitivity to changes in the temperature regime in the Northern Hemisphere for the past four decades are noted. The features of snow cover variability in Eurasia and North America are presented.

The ecological and economic advantages of carbon reinforced concrete—Using the C3 result house CUBE especially the BOX value chain as an example

AbstractAgainst the background of global warming and the associated need to drastically reduce energy and resource consumption, action must also be taken in the building sector. Resource‐efficient construction methods must be used that nevertheless allow the increasing construction tasks in areas such as infrastructure and housing to continue to be fulfilled. In order to successfully introduce a new construction method to the market, the aspects of recyclability and economic efficiency are essential, in addition to important government requirements for climate neutrality and technical performance. Above all, the economic viability, that is, the economic advantageousness, as well as its simple applicability compared to competing systems, decides on the success and widespread use of a new technology. Carbon reinforced concrete, with its outstanding technical properties and simultaneous material efficiency, is an important building block toward climate neutrality in the construction industry. It is a promising technology that still has to prove its economic advantages and robust applicability under market conditions. In addition to the infrastructure sector, there is great potential in the area of housing creation, which needs to be tapped for carbon reinforced concrete. For this challenge, it is necessary to design a competitive value chain that allows the realization of marketable products in mass production on existing plant technology. The article gives a short overview of the economic and ecological status quo in the field of prefabricated construction with carbon concrete, using the example of the C3‐result building CUBE. In particular, the CUBE‐BOX, which is made of prefabricated and semi‐prefabricated parts, is examined in more detail and the carbon reinforced concrete components used are compared with classic reinforced concrete constructions in terms of sustainability. In this context, the conceivable global climate protection contribution of the carbon reinforced concrete construction method is forecast based on potential market segments.

Evolution Characteristics of Sand-Dust Weather Processes in China During 1961–2020

The spring sand-dust weather can be disastrous in China. It seriously endangers agricultural production, transportation, air quality, people’s lives and property, and is a subject of sustained and extensive concern. Currently, few studies have been conducted to analyze sand-dust events in North China from the perspective of sand-dust processes. Although there are a few studies on the spatio-temporal variation characteristics of sand-dust processes, they are mainly based on outdated data or case studies of major sand-dust events. In this study, the evolution characteristics of sand-dust processes in China over the last 60 years are studied based on the identification method and several characteristic quantities (including duration and impact range) of sand-dust weather processes defined in the Operational Regulations of Monitoring and Evaluation for Regional Weather and Climate Processes newly issued by the China Meteorological Administration in 2019. First, through statistics, we obtain the annual occurrence frequency, annual days, and the annual number of affected stations of sand-dust processes (including sand-dust storms, blowing sand, and suspended dust) from January 1961 to May 2021. Based on the Mann–Kendall test (MK) and Ensemble Empirical Mode Decomposition (EEMD), we analyzed evolution trends and probability distribution characteristics of annual occurrence frequency, annual days, and the annual number of affected stations of sand-dust processes. In addition, we investigate the start time of the first and the last dust processes in each of the past 60 years, as well as the seasonal distribution characteristics of sand-dust processes. The results show that under the background of global warming, the sand-dust weather in China tends to decrease significantly. Specifically, the annual occurrence frequency and annual days showed an upward trend before the 1980s and a significant downward trend after that, as well as the significant turnarounds in the annual number of dust processes that occurred in the 1990s and around 2010. Moreover, the sand-dust processes tend to start later and end earlier. The sand-dust processes are mainly concentrated between March and May, with the highest occurrence probability in April.

Evaluating Cumulative Drought Effect on Global Vegetation Photosynthesis Using Numerous GPP Products

The increasing trend in drought events under the background of global warming makes it more important to understand the drought effect on vegetation photosynthesis. While diverse global gross primary production (GPP) datasets were adopted to investigate the drought impact on photosynthesis, few studies focused on the discrepancies of drought response among different GPP datasets, especially for the cumulative drought impact. Therefore, a total of twenty-six global GPP datasets based on process, machine learning (ML), and light-use efficiency (LUE) model schemes were obtained to appraise the cumulative impact of drought stress on photosynthesis from 2001 to 2010. Moreover, a relatively reliable global pattern of drought’s cumulative effect on vegetation photosynthesis was acquired from these global GPP products through probability analysis. The results illustrated that the cumulative impact of drought existed in 52.11% of vegetation cover land with the cumulative time scales dominantly at a short term (1–4 months, 31.81%). Obvious heterogeneity of the drought cumulative effect in space and different vegetation functional types was observed, as the reliability of the drought effect decreased with latitude decreasing and a higher sensitivity to drought in herbaceous vegetation than woody plants. Our findings highlighted the importance of ways in characterizing moisture conditions across vegetation types among various GPP models and the necessity of GPP dataset selection in investigating drought effect on photosynthesis.

Significant Increase in Population Exposure to Extreme Precipitation in South China and Indochina in the Future

Extreme precipitation events cause severe economic losses and can seriously impact human health. Therefore, it is essential to project possible future changes in the population’s exposure to precipitation extremes against the background of global warming. On the basis of model outputs from phase 6 of the Coupled Model Intercomparison Project, our study shows that both the frequency and intensity of extreme precipitation are likely to increase in the South China and Indochina region in the coming century, especially under the business-as-usual Shared Socioeconomic Pathway (SSP) scenario, SSP5-8.5. The largest population exposure can be expected under the SSP2-4.5 scenario, both in South China and Indochina. If early adoption of mitigation measures via the SSP1-2.6 scenario can be achieved, it may be possible to limit the average population exposure in South China to a relatively low level, while Indochina’s may even be smaller than it is currently. In terms of spatial distribution, the maximum population exposure is most likely to be centered in southern South China. This study also reveals that the contribution of the population–climate interaction to population exposure is likely to increase in the future, and different contributions from the factors of climate and population correspond to different emission policies. Under SSP2-4.5, the importance of climate change and the population–climate interaction is more likely to increase.

Deficit Irrigation at Pre-Anthesis Can Balance Wheat Yield and Water Use Efficiency under Future Climate Change in North China Plain.

Simple SummaryAdopting deficit irrigation (DI) to improve crop production and safeguard groundwater resources is of great importance in water scarce regions, e.g., the North China Plain (NCP). Under the background of global warming, it is worth investigating whether DI continues to play such a key role under future climate change scenarios. Thus, we studied the effect of DI on wheat yield and water use efficiency under future climate change scenarios. We found that moderate deficit irrigation (DI3, ≤0.4 PAWC at sowing to flowering stage) under the N3 (150 kg N ha−1) condition was identified as the optimum irrigation schedule for the study site under future climate change scenarios. However, the compensation effect of DI3 on yield and water use efficiency (WUE) became weak in the future. To conclude, in water scarce regions of NCP, DI remains an effective strategy to maintain higher yield and enhance water use under future climate scenarios.Background. Deficit irrigation (DI) is a feasible strategy to enhance crop WUE and also has significant compensation effects on yield. Previous studies have found that DI has great potential to maintain crop production as full irrigation (FI) does. Therefore, adopting DI to improve crop production and safeguard groundwater resources is of great importance in water scarce regions, e.g., the North China Plain (NCP). Under the background of global warming, it is worth investigating whether DI continues to play such a key role under future climate scenarios. Methods. We studied the response of winter wheat yield and WUE to different DI levels at pre-anthesis under two Shared Socioeconomic Pathways (SSPs) scenarios (SSP245 and SSP585) using the Agricultural Production Systems Simulator (APSIM) model driven by 21 general circulation models (GCMs) from the Coupled Model Inter-Comparison Project phase 6 (CMIP6). Additionally, we explored the effects of different nitrogen (N) fertilizer application rates on DI. Results. We found that simulated wheat yield would increase by 3.5–45.0%, with WUE increasing by 8.8–46.4% across all treatments under future climate change. Moderate deficit irrigation (DI3, ≤0.4 PAWC at the sowing to flowering stage) under the N3 (150 kg N ha−1) condition was identified as the optimum irrigation schedule for the study site under future climate change. However, compensation effects of DI3 on yield and WUE became weak in the future, which was mainly due to increased growing season rainfall projected by GCMs. In addition, we found that N fertilizer application could mitigate the effect of DI3. Conclusions. We highlight that in water scarce regions of NCP, DI remains an effective strategy to maintain higher yield and enhance water use under future climate scenarios. Results strongly suggest that moderate deficit irrigation under a 150 kg N ha−1 condition could mitigate the contradiction between production and water consumption and ensure food safety in the NCP.

Seasonal Variation of Vegetation and Its Spatiotemporal Response to Climatic Factors in the Qilian Mountains, China

The purpose of this study is to reveal the seasonal difference in vegetation variation and its seasonal response to climate factors in the Qilian Mountains (QM) under the background of global warming. Based on the MOD13 A2 normalized difference vegetation index (NDVI) data and meteorological data, this study analyzed the spatiotemporal dynamics and stability of vegetation in different seasons by using the mean value method, trend analysis and stability analysis method, and discussed their seasonal responses to climatic factors based on the correlation analysis method. The results show that the vegetation cover in the QM experienced a significant upward trend in the past 21 years, but there were obvious spatial differences in vegetation change in different seasons. The growth rate of vegetation in summer was the fastest, and summer vegetation provided the most significant contribution to the growing season vegetation. The order of vegetation stability in the QM among the seasons was growing season > summer > spring > autumn. The vegetation change was obviously affected by temperature in spring, while it was mainly controlled by precipitation in the growing season and summer. The response of vegetation to climatic factors was not significant in autumn. Our results can provide important data support for ecological protection in the QM and socioeconomic development in the Hexi Corridor.

Hypoxia Induces Oxidative Injury and Apoptosis via Mediating the Nrf-2/Hippo Pathway in Blood Cells of Largemouth Bass (Micropterus salmoides)

Investigating how aquatic animals respond to hypoxia brought about by changes in environmental temperature may be of great significance to avoid oxidative injury and maintain the quality of farmed fish in the background of global warming. Here, we investigated the effects of hypoxia on oxidative injury and environment-sensing pathway in blood cells of Micropterus salmoides. The total blood cell count (TBCC) and Giemsa staining showed that hypoxia could lead to damage of blood cells. Flow cytometry analysis confirmed that the apoptosis rate, Ca2+ level, NO production and ROS of blood cells were significantly increased under hypoxia stress. Environment-sensing pathways, such as Nrf2 pathway showed that hypoxia resulted in significant up-regulation of hiF-1 alpha subunit (Hif-1α), nuclear factor erythroid 2-related factor 2 (Nrf2) and kelch-1ike ECH- associated protein l (Keap1) expression. Meanwhile, the expression of Hippo pathway-related genes such as MOB kinase activator 1 (MOB1), large tumor suppressor homolog 1/2 (Lats1/2), yes-associated protein/transcriptional co-activator with PDZ-binding motif (YAP/TAZ), protein phosphatase 2A (PP2A) were significantly increased in blood cells after hypoxia exposure. In addition, hypoxia stress also increased the expression of catalase (CAT) and glutathione peroxidase (GPx), but decreased the expression of superoxide dismutase (SOD). Consequently, our results suggested that hypoxia could induce oxidative injury and apoptosis via mediating environment-sensing pathway such as Nrf2/Hippo pathway in blood cells of M. salmoides.

MaxEnt Modeling to Estimate the Impact of Climate Factors on Distribution of Pinus densiflora

Pinus densiflora is an important evergreen coniferous species with both economic and ecological value. It is an endemic species in East Asia. Global climate warming greatly interferes with species survival. This study explored the impact of climate change on the distribution of this species and the relationship between its geographical distribution and climate demand, so as to provide a theoretical basis for the protection of P. densiflora under the background of global warming. This research used 565 valid data points and 19 typical climatic environmental factors distributed in China, Japan, and South Korea. The potential distribution area of P. densiflora in East Asia under the last glacial maximum (LGM), mid-Holocene, the current situation and two scenarios (RCP 2.6 and RCP 8.5) in the future (2050s and 2070s) was simulated by the MaxEnt model. The species distribution model toolbox in ArcGIS software was used to analyze the potential distribution range and change of P. densiflora. The contribution rates, jackknife test and environmental variable response curves were used to assess the importance of key climate factors. The area under the receiver-operating characteristic curve (AUC) was used to evaluate model accuracy. The MaxEnt model had an excellent simulation effect (AUC = 0.982). The forecast showed that the Korean Peninsula and Japan were highly suitable areas for P. densiflora, and the area had little change. Moreover, during the LGM, there was no large-scale retreat to the south, and it was likely to survive in situ in mountain shelters. The results suggested that Japan may be the origin of P. densiflora rather than the Shandong Peninsula of China. The distribution area of P. densiflora in the mid-Holocene and future scenarios was reduced compared with the current distribution, and the reduction of future distribution was greater, indicating that climate warming will have certain negative impacts on the distribution of P. densiflora in the future. The precipitation of the warmest quarter (Bio18), temperature seasonality (Bio4), mean annual temperature (Bio1) and mean temperature of the wettest quarter (Bio8) had the greatest impact on the distribution area of P. densiflora.

Chromosome-level genome assembly of the diploid blueberry Vaccinium darrowii provides insights into its subtropical adaptation and cuticle synthesis

Vaccinium darrowii is a subtropical wild blueberry species that has been used to breed economically important southern highbush cultivars. The adaptive traits of V. darrowii to subtropical climates can provide valuable information for breeding blueberry and perhaps other plants, especially against the background of global warming. Here, we assembled the V. darrowii genome into 12 pseudochromosomes using Oxford Nanopore long reads complemented with Hi-C scaffolding technologies, and we predicted 41 815 genes using RNA-sequencing evidence. Syntenic analysis across three Vaccinium species revealed a highly conserved genome structure, with the highest collinearity between V. darrowii and Vaccinium corymbosum. This conserved genome structure may explain the high fertility observed during crossbreeding of V. darrowii with other blueberry cultivars. Analysis of gene expansion and tandem duplication indicated possible roles for defense- and flowering-associated genes in the adaptation of V. darrowii to the subtropics. Putative SOC1 genes in V. darrowii were identified based on phylogeny and expression analysis. Blueberries are covered in a thick cuticle layer and contain anthocyanins, which confer their powdery blue color. Using RNA sequencing, we delineated the cuticle biosynthesis pathways of Vaccinium species in V. darrowii. This result can serve as a reference for breeding berries whose colors are appealing to customers. The V. darrowii reference genome, together with the unique traits of this species, including its diploid genome, short vegetative phase, and high compatibility in hybridization with other blueberries, make V. darrowii a potential research model for blueberry species.

Synergistic Effects of PDO and IOD on Water Vapor Transport in the Preflood Season over South China

It is urgent to improve the prediction accuracy of precipitation in the preflood season (PFS) over South China (SC) under the background of global warming, and thus the research of water vapor conditions is the key. For the period of 1960–2012, using the daily precipitation data from 60 meteorology stations in SC and National Centers for Environmental Prediction (NCEP) reanalysis data, the synergistic effect of PDO (the Pacific Decadal Oscillation) &IOD (the Indian Ocean Dipole Mode) on water vapor transport process to frontal/monsoon precipitation is revealed, based on the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT_4.9). For the frontal precipitation, the positive PDO phase (PDO+) compared with the negative PDO phase (PDO−), there is more water vapor over the West Pacific (WP), the northern South China Sea (SCS), and the Bay of Bengal (BOB). Water vapor for frontal precipitation mainly comes from WP and SCS. When PDO and IOD are in phase resonance, the water vapor transport tracks from the SCS, WP are shorter and westward, so more water vapor is transported to SC, the precipitation efficiency of water vapor to PFS precipitation is higher too. For the summer monsoon precipitation, the tropical Indian Ocean (IO)-BOB is rich in water vapor, especially for PDO−& IOD+. The main water vapor transport tracks are the cross-equatorial flows in the IO, BOB and SCS. The precipitation efficiency of water vapor from the IO-BOB is higher for the positive IOD phase (IOD+) than that for the negative IOD phase (IOD−); however, the precipitation efficiency of water vapor from SCS is higher for the IOD− than that for IOD+. Compared with frontal precipitation, the strong westerly anomaly in the northern IO increases the water vapor transport from the north IO, BOB to SC during monsoon precipitation. For the PDO+&IOD+, the stronger Indian Low and cyclonic anomaly in the WP increases the water vapor transported from the IO-BOB to SC, improving the precipitation efficiency of water vapor. Understanding the synergistic effect of the PDO and IOD on water vapor transport will help to improve the accuracy of precipitation prediction, and reduce the negative impact of drought and flood disasters.

Impact of High-Speed Rail Construction on the Environmental Sustainability of China’s Three Major Urban Agglomerations

Under the background of global warming, it is of great significance to explore how to realize environmentally sustainable development. This paper takes China’s three major urban agglomerations as the research objects: Yangtze River Delta, Beijing–Tianjin–Hebei, and Pearl River Delta. Generally, we use carbon emission efficiency to represent the sustainable development of the environment. Then we use the city-level panel data of the three urban agglomerations from 2006 to 2019 to construct the slacks-based measure integrating data envelopment (SBM-DEA) model for calculating each city’s carbon dioxide emission efficiency. Finally, we construct the spatial difference-in-differences (SDID) model to explore the impact of high-speed rail construction on each urban agglomeration’s carbon dioxide emission efficiency and its internal mechanism. The findings are as follows: (1) On the whole, high-speed rail construction improves urban agglomerations’ carbon dioxide emission efficiency. Meanwhile, it has a positive spatial spillover effect on surrounding areas. (2) In terms of urban agglomerations, high-speed rail construction has significantly promoted carbon emission efficiency in the Beijing–Tianjin–Hebei region. However, it has had negative external effects on the surrounding areas. (3) From the perspective of mechanism analysis, the construction of high-speed rail has promoted manufacturing agglomeration in the Pearl River Delta region and, at the same time, has had a negative impact on the local carbon dioxide emission efficiency. This study has strong policy implications for promoting the sustainable development of the three major urban agglomerations.