An objective method is proposed to identify the regional rainstorm event by tracing contineously the rainstorm area, according to the extent of rainstorm area and the distance between the rainstorm areas on two consecutive days. Moreover, the comprehensive intensity assessing method is developed basing on the intensity, persistency and extent of the regional rainstorm event. Using the daily precipitation data from 2287 stations in China during 1961-2016, the historical regional rainstorm events are identified and the climatology and changing trends of the events are revealed. It is found that, China’s regional rainstorm process averages 38.5 times per year. The regional rainstorm event occurs in every month of the year but mainly from April to September. The frequency of the event is the most in July and August, while the duration is longer, the range is wider and the comprehensive intensity is stronger in June, which is related to the Meiyu phenomenon in the middle and lower reaches of the Yangtze River. Climatically, the average time of the first occurrence of regional rainstorm is March 6, and the average time of the last occurrence is November 14 in a year. From 1961 to 2016, the first occurrence date of regional rainstorm in China is obviously advanced, the last occurrence date is obviously backward, and the rainstorm period is obviously increased. The annual occurrence frequency increased slightly, but the frequency of strong regional rainstorm increased obviously. The coverage area and comprehensive intensity of the regional rainstorm show a significant increase. The variation trend of regional rainstorm of southern type is basically consistent with that of the whole country. The first occurrence date of the regional rainstorm of northern type is advanced, the last occurrence date is pushed back, the occurrence frequency is slightly decreased, and there is no significant change in coverage, duration and comprehensive strength.
The selection of different anomaly indicators will make a significant difference to study the long-term variation of precipitation in a wide range of areas using surface observation data. Daily precipitation data of 2139 national stations in the Chinese mainland were used to construct the regional average time series of precipitation, precipitation days and precipitation intensity, obtained from different indicators. These series were compared to explore the deviation of the long-term trend estimation in precipitation for western China, eastern China, and the entire China. The results shows that from 1951 to 1957, the regional average raw values of precipitation, precipitation days, and precipitation intensities in China had spuriously high biases due to the lack of data from stations in western China, which caused large deviations in the linear trend estimates from 1951 to 2016. In western China, the time series of the regional average precipitation anomaly percentages had excessive fluctuations. The changes in series of anomalies and normalized anomalies were reasonable in every region. The regional average time series of the original values and anomaly values of precipitation amount and days of the entire China basically reflected the precipitation changes in the humid regions in eastern China, while the precipitation anomaly percentages were mainly composed of the precipitation changes in the arid regions. Normalized anomaly could comprehensively reflect the precipitation changes in humid regions and arid regions.
Yalong River basin is an important hydropower base in China. The runoff variation of Yalong River basin under climate change scenarios in future will directly affect the operation safety and power generation dispatch of cascade reservoirs. Therefore, it is necessary to study the impact of climate change on the runoff of Yalong River basin. Firstly, the the monthly SWAT model of the watershed is established, then the meteorological data of each station is predicted by using SDSM from 2006 to 2100. Finally, the future runoff of Yalong River basin is simulated by using the calibrated SWAT model from 2006 to 2100. The results show that the runoff of Yalong River will increase in the future, and increase synchronously with the enhancement of radiation forcing. The annual average runoff growth rates of RCP2.6, RCP4.5 and RCP8.5 are 8.9%, 12.5% and 16.7% respectively, and the annual runoff of 2020S, 2050S and 2080S under three RCPs shows different trends. Under the RCP2.6, it increases gradually to the peak value and then decreases slightly. Under the RCP4.5, it increases gradually to the peak value and then stabilizes. While under the RCP8.5, it increases continuously. In terms of annual distribution of runoff, the proportion of runoff in flood season under three RCPs decreases first and then increases in the three periods of 2020S, 2050S and 2080S. The overall trend in the whole forecast period is decreasing. Under the RCP2.6, RCP4.5 and RCP8.5 concentration paths, the mean proportion of the whole forecast period decreases from 75.9% of the base period to 72.9%, 72.0% and 71.2%, respectively. The increase of runoff will have a greater impact on the flood characteristics of the basin. Therefore, the designed flood in the basin should be revised and flood control dispatching schemes adjusted to reduce the operational risk of cascade reservoirs and to improve the efficiency of power generation dispatching in the Yalong River basin due to climate change.
Based on the latest economic and demographic census and annual statistical yearbooks, development of national economy for 2010-2100 under the Shared Socioeconomic Pathways (SSPs) was predicted in China using Cobb-Douglas economic model by taking the “Universal Two-Child” policy into account. And contributions of three main influencing factors, namely, labor input, capital input and total factor productivity, to economy were analyzed. The results are as follows: (1) under SSPs, economy will continuously grow in China. The growth rate of GDP will remain around 6% before 2030, but a rapid decline is predicted in the 2030s-2060s. Since the 2070s, growth rate of GDP will be lower than 0.5% under SSP1 and SSP4, and be 0.5%-1.5% under SSP2, SSP3 and SSP5. (2) Among three main influencing factors of economic development, the labor input will reduce until the 2060s and then increase under SSP3. On the contrary, it will rise up to peaking in the 2020s and then decrease under other SSPs. When comes to the capital input, it will keep rising up and gradually become steady from the 2080s under SSP1 but will show an increase trend under SSP2、SSP3 and SSP5 with a slight decrease in the 2060s and 2070s under SSP4. Total factor productivity will increase under all SSPs. (3) Since the reform and opening up in 1978, capital input has been the most important factor affecting economy in China. In the future, total factor productivity will gradually become the main factor to economic development under SSP1 and SSP2. However, capital input will continuously play a major role in the economic development under SSP5.
In this study, cooling degree-day based on wet bulb temperature (WCDD) was proposed as an index to reflect building cooling energy consumption. The applicability of WCDD was validated by analyzing the relationships between cooling energy loads simulated by TRNSYS software and WCDD in four cities representing different climate zones from 1961 to 2012. The results showed that cooling degree-day based on dry bulb temperature (DCDD) cannot fully explain the variations of cooling loads except Shanghai, with only explaining 17%?60% of monthly cooling loads in Harbin, Tianjin and Guangzhou. On the contrary, WCDD can explain 67%?98% of monthly cooling loads in all selected cities, indicating that WCDD can be well reflect the variations of cooling energy consumption. In addition, there are great differences in the explanation of WCDD for cooling loads in different zones with different base wet-bulb temperatures. In Harbin and Tianjin, the WCDD with the base temperature of 16.85℃ can explain the monthly cooling loads best. However, there are no significant differences in the explanation of cooling loads by WCDD with three base temperatures in Shanghai and Guangzhou. This study verifies that WCDD can be well used to reflect the building cooling energy consumption in different climate zones as a reliable index. In addition, different optimal base temperatures in calculating WCDD should be taken to efficiently reflect the cooling energy consumption in different climate zones.
Based on MODIS MCD12Q2 data, this paper applied trend analysis and correlation analysis methods, combined with remote sensing precipitation and temperature data products, to explore the temporal and spatial variation of vegetation phenology and its relative factors in the Xinjiang Tianshan Mountains from 2001 to 2014. The start of season (SOS) at the Xinjiang Tianshan Mountains showed obvious vertical distribution characteristics, centralized from 10 March to the 15 May. The 14-year average of SOS over the whole area was 20 March; the end of season (EOS) had zonal distribution characteristics, centralized from 1 October to 25 October. The SOS in the Xinjiang Tianshan Mountains showed insignificant delay trend in the mountainous area, and insignificant advancing trend in the oasis and plain areas. The EOS presented insignificant advanced trend. Precipitation and temperature are important factors influencing the phenological period of Tianshan vegetation. The beginning of phenology is most affected by the spring temperature, and it is also affected by the winter precipitation in the previous year, which is positively correlated with precipitation and negatively correlated with temperature. Summer and autumn precipitation are the main influencing factors of the EOS of vegetation in Tianshan Mountains.
The long-term low greenhouse gas emission development strategy is another key document after the nationally determined contribution, both of which serve as measures of each Party’s mitigation efforts. This study compares and analyses the 12 long-term low-emission development strategies submitted to the UNFCCC secretariat, and summaries key findings from perspectives including the storylines, main contents and the challenges ahead. It is found that the long term emission reduction ambitions are very different among all countries and the breakdowns of national targets into targets by sector and by gas type are still very preliminary. At the same time, considering the big gap between the mid-to-long term mitigation ambitions and the needs to achieve the global temperature increase target, the very limited economic feasibility analysis on main tasks and measures, the gap between the climate finance assistance and the targets set by UNFCCC, there are still great challenges ahead regarding the implementation of the strategies. Based on the key findings, policy recommendations are proposed mainly from four perspectives, including keeping tracking analysis on the submitted long-term strategies and the related key strategies, enhancing analysis on the two-step mitigation targets and tasks in line with China’s two-step approach to build China into a great modern socialist country by the middle of the century, intensifying trimming researches and extended researches on the weakest parts regarding the mitigation pathway, reinforcing analysis on crosscutting strategic issues closely related to the long-term emission reductions.
The new rules of the enhanced transparency framework of the Paris Agreement adopted at the end of 2018 significantly enhance the requirements for greenhouse gas (GHG) inventories consistency for developing countries. The authors recalculated the 2005 GHG inventory, which is the base year of China’s nationally determined contribution, based on the requirements for recalculation of GHG inventories in the IPCC inventory guidelines. The emissions of recalculated 2005 national GHG inventory was 8.015 billion tons of CO2-eq (excluding LULUCF). It increased by 6.6% after recalculation, due to the addition of new sources or sinks, updating of some activity data and emission factors, and using updated methodologies. The energy sector has the greatest impact on the increase in total emissions after recalculation, with an increase of 426 million tons of CO2-eq. The increase in CO2 is mainly due to the revision of fossil fuel consumption in 2005 by the “third census”. The increase in CH4 and N2O emissions is mainly due to including new sources. In the future, China will carry out recalculations more frequently. It is suggested that the study of the time series consistency of China’s GHG inventory preparation should be strengthened in conjunction with the new guidelines to better support domestic climate change decision and to meet the compliance requirements under the future transparency framework.
Based on the economic development of the provinces and the characteristics of energy demand since the New Normal, this paper focuses on the national regional coordinated development strategy and adopts China Multi-Regional Computable General Equilibrium (CMRCGE) model to analyze the economic and social development, energy demand and carbon emissions of the provinces during the 14th Five-Year Plan (FYP) period (2021-2025). The main conclusions include: (1) Under the guidance of the regional coorlinated development strategy, it is estimated that by the end of the 14th FYP, 13 provinces/municipalities will have a per capita GDP of more than US\$15000, and 16 provinces/municipalities will have a per capita GDP of US\$10000?15000. All provincial economies are expected to achieve steady and rapid development by the end of the 14th FYP. (2) The total energy consumption of the provinces is expected to reach 5.45 billion tce in 2025 (excluding Tibet), and the average annual growth rate is about 1.5%. The growth of energy demand will remain in low speed. The focus of energy demand will gradually shift from the eastern to the middle area, while the proportion of energy use in the western provinces will remain basically stable, which is basically consistent with the economic development stage and regional coordinated development strategy. (3) The annual average carbon intensity (mainly considering energy use carbon emissions) during the 14th FYP will drop approximately 5.4%, with most provinces dropping by more than 4.0%. The trend of a significant decline in carbon intensity in recent years is expected to continue.
An assessment framework was established to improve the estimation accuracy of emission reduction potential of shifting containers from road to rail (SRR), based on the analysis of SRR’s emission reduction principle. To this end, the activity-modal structure-energy intensity-emission factor (ASIF) methodology was revised by integrating the parameters of activity type, emission category, equipment structure, and energies’ life-cycle emission factor, which considered the emissions from main haulage, loading and unloading, operations by electric vehicles and equipment, pre- and post-haulage, transshipment between road and rail for the door-to-door transport chain of both empty and loaded container movement. Then, the export container transportation between Yiwu and Ningbo Port Area was taken for case study, and the input data was collected by use of face-to-face interview and published literature. The results showed that the emission reduction rate of CO2 for one TEU SRR of transport demand would be overestimated by 0.50-36.73 percentage points, when necessary factors are ignored. In the best-case SRR scenario, the CO2 emissions will be reduced by 34.2 kt with a reduction rate of 13.58%. The findings could provide theoretical support for the relevant government departments to objectively evaluate SRR’s emission reduction potential and to make efficient SRR policy measures.
Taking the city of Guangzhou as a case study, a Long-range Energy Alternatives Planning (LEAP)-Guangzhou Transportation model was developed to simulate future energy consumption and CO2 emission trends during 2017-2050 under three scenarios: policy scenario (PS), low-carbon scenario (LCS), and green and low-carbon scenario (GLCS). Then the emission reduction potentials, the development direction and path of transportation sector were discussed. Results show that CO2 emission of transportation sector in Guangzhou will peak around 2035 under PS scenario, but with more stringent policies in the LCS and GLCS scenarios, the peak timing is expected to advance to 2025 and 2023, respectively. In order to promote the low-carbon development of urban transportation, it is necessary to develop railway and waterway transportation to form an integrated transportation system; fully implement the public transportation priority strategy to effectively control the number and the frequency of private cars; and promote the cleanliness of energy structure and the energy efficiency.
The transparency system, which mainly includes reporting and review of information submitted by Parties, is an important guarantee for the effective implementation of the Paris Agreement. The Paris Agreement established the enhanced transparency framework and adopted the implementation rules at the end of 2018, forming an enhanced transparency system. Building on existing transparency experiences and practices, this system applies common modalities, procedures, and guidelines while providing flexibility and support to developing countries to enhance transparency, reflecting common but differentiated obligation by Parties under the Paris Agreement. The system is conducive to improving the quality and comparability of Parties’ national reports, urging all Parties to fulfill their obligations and enhancing mutual trust in the multilateral mechanisms of global climate governance. However, compared with the current practice, this system has imposed a strong burden on developing countries while not strengthening respective support, and the overall operational efficiency of the system itself remains to be seen. To this end, countries should prepare for domestic institutional mechanisms, and the international community should continue to support developing countries for their compliance and strengthen their corresponding capacity building.
Climate change, as a typical “non-traditional security” issue, whose position in national security affairs has been debated for a long time. Securitization theory is an important method to analyze the non-traditional national security. The securitization factor method proposed by the Copenhagen School is used to compare the Sino-U.S. climate securitization level in this paper. The results are as follows. Security is an inter-subject phenomenon. China is in the process of “securitization” with political and scientific authority as main body, and the U.S. is in “non-securitization” process caused by political authority. Inter-subjectivity is identification degree of main body to “existential threat”. It is inharmonious between inter-subjective and progress of climate securitization in China. The top political leader has a higher level of climate securitization than the public. The means of expression of climate existential threat is a restrictive factor to public climate securitization level, which includes single perspective and media of securitization. The modes of global perspective and inter-state graphical comparison are induced to enhance the expression effect of existential threat, which can propose method to promote climate securitization level of China.