In this study, based on daily gauge precipitation data of 2480 stations from 1961 to 2016, the summer extreme precipitation event was defined using the 95th percentile, and the changes in persistent (last for at least 2 d) and non-persistent (1 d) extreme event in China were analyzed. The results indicate that under global warming, the contribution of extreme precipitation to total precipitation increased in most of China, but it decreased in the central part of Inner Mongolia and the Sichuan Basin. In North China and Southwest China, both persistent and non-persistent extreme precipitation totals decreased; the decreasing trend of persistent extreme precipitation was more significant; extreme precipitation event occurred as non-persistent event. Meanwhile, in the Yangtze River Basin and South China, both extreme precipitation totals increased; especially persistent extreme precipitation increased obviously; extreme precipitation events occurred more as persistent ones.
Based on the daily precipitation data from 66 stations in the Meiyu area of Yangtze-Huai River Basin and the NCEP/NCAR reanalysis data from 1960 to 2014, several extreme precipitation indices were used to explore the spatial and temporal variation characteristics and influencing factors of regional summer extreme precipitation with the help of trend analysis, EOF analysis and composite analysis. The main results are as follows: (1) The summer extreme precipitation indices mainly show an upward trend, and the significant ascending zone is mainly located in the eastern part of the region. (2) The first eigenvector of these indices shows a uniform “+” distribution pattern but it’s stronger in the north area, and the second has a “positive in the northwest and negative in the southeast” distribution pattern. Temporal coefficient of the first mode shows an upward trend but the second temporal coefficient has no obvious trend. (3) In the typical years of strong (weak) summer extreme precipitation, the location of the Western Pacific Subtropical High extends westward (eastward), and the mid-latitude region shows the meridional (zonal) circulation characteristics, which is favorable (unfavorable) for the occurrence of the extreme precipitation in the Yangtze-Huai River region. Meanwhile, the intensity of the summer extreme precipitation in the Meiyu area is abnormally strengthened (weakened) when the ascending motion is enhanced in the middle and lower troposphere (when the airflow divergence in the middle troposphere is enhanced), and the water vapor flux is enhanced and convergent (weakened and divergent), leading to more (less) extreme precipitation.
To understand the energy balance and physical attributes of different profile process of alpine grassland soil freeze-thaw period furtherly, the methods of heat transfer, the amplitude and phase on soil heat flux of the different depth were calculated in this paper, and the parameters of soil thermodynamic characteristics during different years were analyzed. The results showed that the method of heat transfer could well describe the variation characteristics of soil heat flux of different soil layers. Average soil temperature of different depths from the surface to the depths gradually showed the hysteresis effects, meanwhile, the surface (T0cm) maximum temperature appeared about July, however, the highest temperature occurrence time of the deeper soil T160cm and T320cm appeared August and September, respectively. With the increase of soil depths, its amplitude decreased and the phase delayed. The fitting effect of the measured temperature and the simulation was the best in the middle soil layers, and the correction coefficients were 0.9361, 0.9509 and 0.9133, respectively. In addition, the phase change trends of soil total heat flux and the convective heat flux were similar, but in contrast to the conduction heat flux. Therefore, seasonal change was the dominant factor of affecting on the heat transfer process and the transfer direction of soil profiles.
Circulation feature and water vapor transport of winter precipitation anomaly were studied by using the ERA-Interim reanalysis data and the daily rainfall observations of 49 meteorological stations in winter in Northern Xinjiang during 1979-2016. The analyzed results showed that two routes of water vapor transport had an effect on winter precipitation in Northern Xinjiang. The west water vapor passage was Mediterranean Sea-Black Sea-Caspian Sea-Aral Sea-Balkhash Lake-Northern Xinjiang, the southwest water vapor passage was Red Sea-Persian Gulf/southern Caspian Sea-Balkhash Lake-Northern Xinjiang. Two of the passages, the west water vapor passage was more important. The reasons for more (less) winter rainfall in Northern Xinjiang were that, on 500 hPa, high (Low) pressure was anomaly active in high latitude, transient low-pressure disturbance (high pressure) was unusually active in Siberia and high-pressure ridge (low-pressure trough) was unusually in Iranian plateau. The reasons for more (less) winter rainfalls in the northwest of Northern Xinjiang were that, on 500 hPa, positive (negative) anomaly was active in Scandinavian Peninsula, negative (positive) anomaly was active in Siberia-Iranian plateau, and low-pressure trough (high-pressure ridge) was unusually active in Mediterranean. The reasons for more (less) winter rainfalls in the west of Northern Xinjiang were that, on 500 hPa, negative (positive) anomaly was active in the southwest side of the Balkhash Lake, positive (negative) anomaly was active in Siberia. Three of the distributions, the most main distribution pattern was consistent in wintertime precipitation in Northern Xinjiang.
Under the background of global warming, heat wave events have frequently occurred around the world and increased the mortality risk greatly. Based on the daily meteorological data from 1951 to 2015 and daily mortality data from 2007 to 2013 in three cities (Nanjing, Chongqing, Guangzhou), a heat wave intensity index was firstly designed to quantify the heat waves, and then a distributed lag non-linear model (DLNM) was used to develop the vulnerability models of population under the heat wave events. Finally, Monte Carlo simulation method was run to assess the probabilistic heat wave risk and rated the premiums for heat wave life insurance. The results show that, the heat wave mortality risks and pure premium rates for the elder are both 9 to 28 times that of the young and the pure premium rates are inversely proportional to the level of socioeconomic development. The results in this study can provide guidance for developing weather index-based individual life/health insurance products and give support for the government to adopt comprehensive risk management measures to reduce public health risks.
More frequent high temperature extremes caused by climate change may significantly increase urban water demand and consequently the vulnerability of urban water distribution systems (WDSs). A methodology was developed to quantify the impact of high temperature extremes on urban water demand and WDSs by integrating the methods of climate analogy, end use modeling and WDS hydraulic simulation. A case study on a new development area in Beijing showed that high temperature extremes could lead to an increase in total water demand by 5.7%, equivalent to an increase in per capita daily water demand by 19.83 L, as compared with normal summer. Furthermore, significant increases in water demand were found during morning and evening peak hours, which caused the failure of another 13 percentage points nodes of the WDS to meet the pressure requirement of 28 m.
The change of rice growth period is dominated by the climatic conditions and variety renewal as well as the corresponding field managements. Thirteen agro-meteorological stations data in Northeast China from 1992 to 2012 were used to analyze the changes of rice growth period and its relationship with the warming trend and the adjustment of rice varieties. The results show that the mean temperature and more than 10℃ cumulative temperature of rice growing season increased significantly from 1992 to 2001, the maximum value of the difference in ≥10℃cumulative temperature could reach as high as 500℃?d, then the warming trend slowed down and slightly declined from 2002. Corresponding to the warming trend, it shows an overall opposite feature of the changes of rice phenology in 2002-2012 vs. 1992-2001, the heading stage, milky maturing stage and maturing stage were obviously advanced from 1992 to 2001 by 3.1, 2.9, 4.5 d/10a, respectively, while the transplanting, tillering and maturing stages delayed by 4.6, 4.7, 2.0 d/10a, respectively, in 2002-2012. Though the changes of growth period were affected by many factors, but the sowing to transplanting period and milky maturity to maturing period were shortened by 0.7, 1.6 d/10a in 1992-2001, respectively, and were prolonged by 2.9, 2.8 d/10a, respectively, in 2002-2012. In general, the whole rice growth period was prolonged by 3.7 d/10a in 1992-2012, which was mainly attributed to the extension of vegetative growth periods. The analysis of 12 stations with complete experimental data shows that the rice variety adjustment is constantly implemented in Northeast China to adapt to the changes of climatic conditions, it is shown that over most of the selected stations there was a small deviation between the observed rice growth period and the certificated growth days of variety registration, which means that the selected rice variety could match the in situ climatic conditions for the effective utilization of the local climatic resources, however, there are still some stations (such as Yanji, Meihekou, and Tonghua) in which the deviation between the observed rice growth period and the certificated growth days of variety registration was getting larger due to the enhanced climatic variation, besides, in some stations (such as in Ning’an and Qian Gorlos) there were almost no changes for the certificated growth days of variety registration. Therefore, there is an urgent need for a systematic summary of the climate sciences and the lessons how to adapt the rice production to climate change in Northeast China, and then providing solid scientific support to climate change adaptation for rice production in Northeast China.
Based on the global carbon emissions data from the Carbon Dioxide Information Analysis Center, and population density data from the Socioeconomic Data and Applications Center, the ArcGIS spatial analysis tools were used to integrate population density as an economic-population composite indicator for weighted carbon emissions for 1950, 1980, and 2014. The resulting Global Population-Weighted Carbon Emissions Dataset (at 0.1° × 0.1° resolution) shows that: In 1950, the main carbon emission areas were the eastern part of the United States and Europe. In 1980, the eastern part of China, Japan, and South Korea were added as the main areas of global carbon emissions. In 2014, India and Southeast Asia were newly added as major emission areas. Carbon emissions have increased substantially in general and decreased slightly in a few areas, which is related to the different stages of industrial development. The dataset can reflect the change of global carbon emissions spatial distribution and provide basic data for global climate change research.
The transport sector has high potential for carbon emission growth in the mid- and long- term and has great impact on China’s low carbon transition. A bottom-up energy system model PECE-LIU2017 which includes detailed transport sector module was developed in this study. Three scenarios were developed to discuss different future transport development pathways: the business as usual (BAU) scenario, Nationally Determined Contribution (NDC) scenario and the low-carbon scenario. The low-carbon transition of the transport sector was explored by investigating the main driving factors trend and the impact. The results showed that China’s energy service demand for transport sector will continue to grow in the future. In NDC scenario, CO2 emissions in transport sector will peak at around the year of 2038 while in low-carbon scenario, CO2 emissions will be reduced dramatically from 3 billion tons in BAU to less than 600 million tons by 2050 and peak at around 2030, which will contribute 17.5% of total mitigations to the whole energy system. The total capital investment needs for transport sector during 2016-2050 will be around 15.7 trillion Yuan (RMB), accounting for 53% of national low carbon capital investment demand. By taking measures to improve fuel efficiency, promote new energy vehicles and encourage public travel, the transport sector is able to decarbonize its development pathway in a technical feasible way, and make a great contribution to realize China’s long-term low carbon development strategy.
To combat global climate change, developed countries should take lead in mitigating GHG emissions and provide financial support to developing countries. According to the UNFCCC and its outcomes, developed countries have committed quantified economy-wide emission reduction targets and pledged to mobilize annually US\$100 billion climate finance by 2020. Based on various data sources, a stock-take on the progress in achieving those targets has been conducted, and it shows that developed countries ’ 2020 mitigation targets are lack of ambition, the accounting rules of the targets are still unclear, and some of the developed countries are not on track to meet their 2020 targets; on finance, the definition and scope of climate finance are contentious. The current estimation of climate finance flows shows a significant gap comparing with the US $100 billion target. The finance mechanisms under the UNFCCC need to be further strengthened and the financial needs of developing countries are still rising. The gap in honoring 2020 targets of developed countries could harm the trust among Parties and could be seen as an intention to shift the obligations to developing countries. Therefore, in the UNFCCC process, China and its developing country allies should keep urging developed countries to honor their 2020 commitments and enhance ambition.
It has been acknowledged that the combined NDCs (Nationally Determined Contributions) are rather insufficient to stay within the emission ranges consistent with goals in the Paris Agreement, and a feasible benchmark is needed to set as a reference to guide the countries to strengthen their national contributions in an equitable manner. This paper systematically reviews the equity principles involved in mitigation efforts sharing, covering four dimensions of fairness, namely, emissions responsibility, economic capability, egalitarianism and sovereignty. Specifically, this paper reviews the research progress and allocation schemes that are based on different equity dimensions or combinations of several dimensions, and further classifies the divergent contradictions in this field into three levels, that is, the choice of fairness dimension, the design of allocation mechanism and the specific parameterizations. It is found that the “equitable allocation references” that were set to guide countries to increase NDC ambitions are still flawed in terms of comprehensiveness, consistency, and objectivity. In particular, those studies based on multi-bibliographic analysis as well as integrated allocation model led by developed countries fail to reflect the concerns of developing countries about “fairness”. This paper, therefore, points out that the research needs and new direction of studies of national contributions sharing in the future: it needs to systematically elaborate the allocation schemes from the perspective of developing countries, and also construct a comprehensive, balanced and objective integrated allocation model, so as to enhance China’s discourse power on this issue. Consequently, it will help China better play its role of contributors and leaders in the process of equitable realization of the temperature objectives in the Paris Agreement.
