The steep terrain area in the eastern slope of the Tibetan Plateau is a large deviation area for climate models in the processes of simulating land precipitation, and this deviation has not been effectively improved for a long time. Based on the daily precipitation of 17 global climate models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), the ability of the latest climate models to simulate precipitation climatological characteristics and their intraseasonal evolution over the eastern slope of the Tibetan Plateau during the warm season (May to September) from 2000 to 2014 was assessed. The results show that the positive precipitation deviation in the eastern slope of the Tibetan Plateau exists in most CMIP6 models, and the false precipitation center mainly comes from the over-simulation of the heavy rainfall (precipitation≥6 mm/d), and the simulation of the weak rainfall (precipitation<6 mm/d) is smaller than that of TRMM observation. Although there is a consistent over-simulation of the warm season precipitation in the eastern slope of the Tibetan Plateau, there are large differences in the simulation of precipitation for different months between models. The analysis based on the circulation field shows that the intraseasonal evolution of the heavy rainfall in the eastern slope of the Tibetan Plateau is closely related to the evolution of southerly wind anomalies in the mid-troposphere in the eastern slope of the Tibetan Plateau and east to it. The above results indicate that although the simulation of the mid-tropospheric circulation is not the main factor causing the positive deviation of the simulation of heavy rainfall in the eastern slope of the Tibetan Plateau, the reasonable simulation of the intraseasonal variation of the circulation is a key factor for a model to reproduce the month-to-month variation of heavy rainfall on the eastern slope of the Tibetan Plateau.
Regional Continuity Rainstorm Proceses (RCRP) were analyzed by using the idea of continuous rainstorm tracking and the daily precipitation data of 2481 meteorological stations in China from 1961 to 2019. According to the duration, sphere of influence, maximum daily precipitation and maximum process precipitation of the RCRP, the hazard assessment model and risk regionalization were established and improved. The results show that a total of 2294 RCRP occurred in China from 1961 to 2019, and the risk of each of the top 10 RCRP ranked by the comprehensive intensity index was consistent with the historical record. The spatial distribution of RCRP' risk is similar to the distribution of climate precipitation in China, and it gradually decreases from southeast to northwest. The high risk areas of RCRP in China are located in South China and Jiangnan region. The seasonal spatial distribution of the risk is related to the characteristics of precipitation in the same season. The high risk level of spring RCRP in South China reflects the influence of the first flood season in South China. The risk of RCRP in North China and Northeast China in summer is higher than that in other seasons, and the high risk in coastal areas reflected the influence of typhoon and rainstorm. The high risk of autumn RCRP mainly reflects the influence of autumn rain in West China. The single RCRP risk regionalization represents the distribution of the rainstorm and flood disaster degree, and can intuitively judge the distribution of the rainstorm and flood disaster caused by the RCRP. The study enhances the understanding of the evolution of RCRP and is of great significance in predicting the intensity of regional risk in different seasons and sub-seasons of RCRP in the future, and preventing the risk of rainstorm and flood disasters it might bring about.
Based on the latest provincial flood disaster loss data and observational precipitation data of meteorological stations in China, the spatial-temporal characteristics of flood disaster losses and the related hazards from 2001 to 2020 were studied. During 2001-2020, floods have caused an annual average of more than 100 million affected population, with direct economic losses of CNY 167.86 billion yuan. Despite the increasing trend of direct economic losses, the affected population and crop area, fatalities, damaged houses and proportion of direct economic losses to gross domestic product all show decreasing trend in the recent 20 years. The areas are more seriously affected by floods in the upper and middle reaches of the Yangtze River basin, Heilongjiang, Hebei, Gansu, and Guangxi provinces. The fatalities and damaged houses are decreasing while the direct economic losses are increasing in most of China. However, the affected population and crop area show different trend distribution, increasing in northern China while decreasing in southern China. In the past decade, flood losses except fatalities have increased compared to the previous decade in most parts of northern China, especially in Hebei and Heilongjiang provinces. At the same time, total precipitation increases in most parts of northern China, and the amount of heavy rainfall and rainstorm days increase greatly in Heilongjiang and Hebei provinces, which further increases the risk of floods in the relatively vulnerable northern China.
China is a country in the world where landslides disasters have caused serious casualties. Due to the impact of climate change, the occurrence of extreme precipitation frequency and intensity is projected to be on the rise, which will increase the population risk of landslide disasters. This paper coupled the future precipitation data of multiple models in different RCPs scenarios and the population data in SSPs scenario into an established landslides risk model to quantitatively assess the projected changes in China landslides population risk. The results showed that compared with the baseline period (1970-2000), the high-landslide-hazard zones is projected to increase by 5.5% and 7.9%, respectively under the RCP4.5 and RCP8.5 scenarios in the middle 21st century (2031-2060). The Qinghai-Tibet Plateau has the most significant growth. The population risk of landslides disasters in China shows increasing trend and then decreases under the RCPs-SSPs scenarios. Compared with the RCP4.5/SSP2, the average annually casualty of landslide disasters will increase from 639 to 956 under the RCP8.5/SSP3 in the middle 21st century. In the end of the 21st century (2071-2100), due to the decline of exposure population, the average annual casualties of landslide disasters will decrease to 737. In the future, Zhejiang, Guangdong, Sichuan, Yunnan, and Tibet will always be the provinces with the highest casualties of landslides disaster. Therefore, it is necessary to increase risk prevention measures to reduce the population risk of landslides disaster.
According to the target and the peak time of carbon emissions under SSPs scenarios, SSPs were divided into “double carbon” pathway (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP4-3.4, SSP4-6.0) and “high carbon” pathway (SSP3-7.0, SSP5-8.5). The runoff evolution characteristics of Ganjiang River basin were analyzed in two periods of peak carbon dioxide emissions (2028-2032) and carbon neutral (2058-2062) based on the SWAT hydrological model. The results are as follows. (1) Annual mean temperature in the Ganjiang River basin from 1961 to 2017 showed a significant upward trend with a rate of 0.17℃/(10 a), while the precipitation increase slightly with a rate of 17 mm/(10 a). Under the “double carbon” and “high carbon” pathways, the Ganjiang River basin will be in a warm and wet state from 2021 to 2100, with temperature rising and precipitation increasing. (2) In the periods of peak carbon dioxide emissions and carbon neutral, annual runoff shows increasing tendency during “double carbon” pathway. In “double carbon” pathway, monthly runoff shows increasing tendency in all scenarios in flood season, while increasing tendency in SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP4-3.4 and decreasing tendency in SSP4-6.0 in dry season. The intensity of extreme hydrological events under the “double carbon” pathway will be less than under the “high carbon” pathways.
Different from the traditional bottom-up approach, a combination of bottom-up and top-down methods was used to measure the Beijing high spatial resolution CO2 emission inventory. From the bottom-up approach, based on the data of nearly 13000 facilities (power station boilers, industrial kilns, heating boilers), the fossil energy consumption and carbon dioxide emissions of fixed sources were calculated. From the top-down approach, the energy consumption of boilers in different industries were verified using the energy consumption sheet by sectors, thus the systematic errors of the emission inventory were controlled at a macro level. It's found that the central urban area was still the region with the highest carbon density and intensity. To formulate a low-carbon policy for the next stage, Beijing needs to pay more attention to carbon emissions from road traffic, commercial buildings and residents' lives.
Air transport is the fastest-growing sector for carbon dioxide (CO2) emissions in the transportation field. In this study, typical aircrafts of super-large, large, medium, and small size were selected to calculate aviation CO2 emission factors, based on the change of engine fuel consumption rate, time consumption and fuel consumption of different aircraft during take-off, climb out, cruise, approach and taxiing stages. Meanwhile, the per capita CO2 emissions of passengers (CO2 emission factor per passenger turnover) on different aircraft were evaluated according to the CO2 emission characteristics, rated passenger capacity and passenger load of different aircraft. The results showed that the average CO2 emission factors of super-large, large, medium, and small size aircraft within their maximum mileage are 49.8, 31.7, 16.2 and 8.5 kg CO2/km, respectively, and the average CO2 emission factors per passenger turnover are 102.6, 95.2, 81.7 and 112.4 g CO2/(person∙km). Because the engine fuel consumption rate during take-off and climb out is about 2.6-3.4 times and 2.0-2.8 times of the cruise fuel consumption rate, the aviation CO2 emission factor decreases with the flight mileage increase. Air transport is a high carbon emission passenger transport mode, and its per capita CO2 emissions is significantly higher than that of high-speed railway and on-road motor vehicles under the same mileage. It is an effective way to reduce aviation CO2 emissions by improving engine fuel efficiency, reducing short-distance transport, improving the passenger loads and reducing midway transfers.
In this study, a demonstration center of a near-zero energy building in a cold region was selected as a case to carry out the life-cycle carbon emissions accounting of the near-zero energy building. Numerical simulation method was used to select the type of building thermal insulation material, thickness of thermal insulation material, window type, window-wall area ratio, form of heating and air conditioning and building service life, and analyze the influencing factors of carbon emissions in the whole life cycle of the building. The results show that the carbon emissions in the production and transportation, construction, operation and demolition and cleaning stages of building materials account for 51.3%, 1.3%, 47.3% and 0.1%, respectively, in the whole life cycle of near-zero energy buildings. Compared with other buildings, it is found that with the improvement of building energy saving requirements, carbon emissions in the production stage of building materials account for more and more; One-third of the life cycle carbon emissions of near-zero energy buildings are about one-third of ordinary buildings, and one-third of green ones; Through the use of low-carbon environmental protection materials, insulation material thickness between 160-260 mm, window-wall area ratio between 0.1-0.2, solar+ground source heat pump energy supply mode and prolonging the service life of the building can reduce the carbon emissions in the whole life cycle of the building.
Achieving China's goals of carbon dioxide peaking before 2030 and carbon neutrality before 2060 requires a large amount of financial support, and it is urgent to build a climate finance system to match the goals. The Monitoring, Reporting and Verification (MRV) system, an important part of the climate finance system, can not only effectively monitor and report the sources, usage and effectiveness of climate finance, but also make full use of the existing climate finance resources and leverage more money to the climate change field. This paper summarizes and analyzes the latest progress of the international climate finance MRV system and its implications for China through extensive literature review and expert consultation. Since 2010, with the increasing channels and quantity of international climate finance flows, a complete MRV system of bilateral and multilateral public finance has been established, and the MRV system covering more sources, such as private and domestic funds, is further being developed. At the same time, the MRV system of climate finance effects has been gradually established in terms of climate benefits such as climate change mitigation and adaptation effects, and non-climate benefits such as consistency with the Paris Agreement financial targets, contribution to sustainable development goals, etc. China is still at the early stage of climate finance MRV system, and should improve it in terms of top-level design, policy and standards, measurement and reporting, capacity building and international communication and cooperation in the near future.
Nationally Determined Contributions (NDC) is the core central arrangement of Paris Agreement, which reflects the evolution of global climate governance mode from “top-down” to “bottom-up”. 92 communicated or updated NDC by July 1, 2021 were analyzed with comparing method in this research. Seven types of updating patterns were found: increasing the values of quantitative mitigation targets, adjusting the types and coverage of mitigation targets, adding adaptive goals and policies strategy, increasing the 2050 carbon-neutral vision, proactively applying NDC information and accounting guidance, reporting the progress of NDC implementation, supplementing the policy and measures for achieving the goals. It is found that the updated NDCs in some countries have showed some problems that may affect the effectiveness of global climate governance, including increasing the target number but the actual mitigation efforts is regressing, proposing the long-term target to avoid the enhancement of the near-future ambition for target and implementation, and insufficient financial support for NDC implementation, etc. Global climate governance should respect different updating patterns of NDC, to consolidate the “bottom-up" arrangement of the Paris Agreement, and establish a comprehensive and reasonable “ambition view” with enhancing ambition not only on the target, but also on implementation and support.
China's carbon neutrality, aligned with the global 2℃/1.5℃ target, has become a programmatic target to guide China's medium and long-term sustainable development. Through the literature review, the discussion about the important proposition that “carbon neutrality is a broad and profound systematic socio-economic revolution” is presented from two aspects of target connotation interpretation and feasible pathway description. Indeed, China's carbon neutrality aims to net-zero GHG emissions. China should formulate a medium-term action plan based on the phased emission reduction performance to gradually achieve the long-term carbon neutral. And China needs to focus on the alternative transition directions of “zero carbon landscape” dominated by high-share non-fossil energy and “net zero landscape” represented by decarbonization of fossil energy, which likely creates a contradictory picture. Collaborative carbon neutral solutions necessitates the joint support of top-level design from government, cooperation among industries and enterprise practice, with the strong external force of market-oriented tools such as “power market, carbon market, finance market”, to strengthen the collaborative exploration, innovation and application of feasible and affordable zero-carbon, low-carbon and decarbonization technologies, which can relief the transition barriers and the cost of emission reduction as much as possible. In terms of carbon neutralization technology path, energy efficiency technologies, new energy and digitization will run through the process of carbon neutralization. In the short term, the critical task is to strengthen the application of flexible resources such as energy storage and demand response and boost the terminal electrification. In the medium term, it is necessary to strengthen energy interconnection and promote the demonstration application of low-carbon materials and negative emission technologies. And in the long term, it is necessary to evaluate a practical and affordable comprehensive carbon neutralization method to ensure the safety, low-cost and reliability of carbon neutral transition.
This paper reviews three global disaster databases focused on meteorological disasters including Emergency Events Database (EM-DAT) of Belgium, NatCat of Munich Re (NatCat) and Sigma of Swiss Re (Sigma). The differences in purposes, criteria and classification of disaster types across global databases are compared. EM-DAT is mostly used globally due to its free accessibility while NatCat and Sigma are more advantageous on economic loss assessment. The global disaster databases have some bias in the collection of early historical disasters and disasters in undeveloped areas as well as ignoring some small-scale disasters. In the future, it is necessary to further improve the reliability and fineness of disaster data, the standards and specifications of databases, and strengthen the cross-checking of multiple disaster databases in order to lay a solid foundation of data for studying the links between climate change, human activities and meteorological disasters.