By using the NUIST Earth system model v1 (NESM v1) with a constant external forcing, 40-year global tropical cyclone activities were simulated, and the simulation data were compared with the observations (1977-2016). The results show that NESM v1 can simulate vortex structure similar to tropical cyclones in the area where tropical cyclones are active, The spatial distribution and impact range of simulated tropical cyclones are basically consistent with the observations, but the numbers of tropical cyclones in various areas are different from the observations. In addition to North Indian Ocean, the numbers of tropical cyclones in different seasons are similar to the observations. The model has the best simulation in the Northwest Pacific Ocean, it can simulate the formation area and prevailing path of tropical cyclones. The simulation results in the North Indian Ocean are poor. NESM model simulates relative vorticity different from observation, so it cannot simulate the bimodal characteristic in North Indian.
Based on the Hadley Center sea surface temperature data, NCEP/NCAR reanalysis data from 1970 to 2016 and numerical modeling simulation (ECHAM4), the possible effects of sea surface temperature anomalies (SSTA) in 1998 and 2016, which are the super El Ni?o attenuation years, on tropical cyclone (TC) formation and large-scale circulation in the Western North Pacific in August were studied. It is suggested that the SSTA, which was almost opposite in the tropical Indian Ocean and the Atlantic Ocean in 1998 and 2016, is one of the main reasons for the significant difference in the TC genesis number. Tropical and North Pacific SSTA can exert low pressure cyclonic circulation in the Pearl River Delta and south of Japan respectively in August 1998 and August 2016. The anomalous anti-cyclonic response of the tropical Indian Ocean and Atlantic SSTA in 1998 was stronger than the cyclonic anomaly generated by the Pacific SSTA. Therefore, the Western North Pacific Ocean is subject to anti-cyclonic circulation, which makes the TC genesis number less. In 2016, under the combined action of three oceans, the anomalous cyclone in the Western North Pacific led to more TC genesis number. The Pacific meridional mode structure forced an east-west overturning circulation anomaly in the subtropical North Pacific, and the response over the Western Pacific Ocean was opposite to that observed. Therefore, the Pacific meridional model has no positive contribution to the TC genesis number in the Western North Pacific.
Based on the predicted results of 21 global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under RCP4.5 and RCP8.5 scenarios, the annual and seasonal variation characteristics of temperature were analyzed over the Tibetan Plateau (TP hereafter) at global warming threshold of 1.5℃ and2℃. The results show that, when global warming reaches 1.5℃ and 2℃, the warming of the TP are both more notable than global warming. The annual warming is high both in the west and southwest but low in the northeast, while spring warming and winter warming are high in the south but low in the north, and summer warming and autumn warming are both high in the west but low in the east from the spatial distribution, respectively. The increase of mean, maximum and minimum temperature is 2.11℃/2.10℃ and 2.96℃/2.85℃, 2.02℃/2.02℃ and 2.89℃/2.77℃, 2.34℃/2.34℃ and 3.20℃/3.14℃over the TP under RCP4.5/RCP8.5 scenario when the global warming reaches 1.5℃ and 2℃, respectively. Besides, the winter warming over the TP (2.19℃/2.31℃ and 3.13℃/3.05℃) is more remarkable than that of other seasons. There are also regional differences in temperature response at the same warming threshold over the TP under RCP4.5 and RCP8.5 scenarios. The differences of annual and seasonal mean temperature between the two periods when global warming reaches 1.5℃ and 2℃ under two scenarios all exceed 0.5℃, with regional and seasonal differences.
Future changes of climate extremes in the 21st century over Xiongan New Area and Jing-Jin-Ji district were investigated based on high resolution (6.25 km) combined statistical and dynamical downscaling datasets, which were produced using the observation of CLDAS, five sets of regional climate change simulations by RegCM4.4, and statistical downscaling with quantile mapping. Of that, the RegCM4.4 simulations were conducted over East Asia under RCP4.5 scenario driven by five different CMIP5 global climate models of CSIRO-Mk3-6-0, EC-EARTH, HadGEM2-ES, MPI-ESM-MR and NorESM1-M. Validations of the present climate show that the multi-model ensemble mean can well reproduce the spatial distribution of most climate extremes, and better performance can be found in the temperature-related climate extremes. However, some biases can also be observed, especially for the consecutive drought days (CDD). In the context of global warming, increased extreme warm events, decreased extreme cold events and consecutive drought days and increased extreme heavy precipitation events are projected in Xiongan New Area and the whole Jing-Jin-Ji district. In specific, increased TXx (Maximum value of daily maximum temperature) and TNn (Minimum value of daily minimum temperature) can be found, with the value exceeding 2.4℃ and 3.2℃, respectively. More pronounced increase of SU (Number of summer days) over the mountainous areas compared with the plain is observed, while greater increase of TR (Number of tropical nights) is found over the plain. The increase of SU and TR are in the range of 20 ? 40 d and5 ? 40 d, respectively. Both the FD (Number of frost days) and ID (Number of icing days) will decrease, with the decline above 10 d and 5 d, respectively. Precipitation-related climate extremes including CDD, R1mm (Annual count of days when daily precipitation≥1mm) and R10mm (Annual count of days when daily precipitation≥10 mm) are mainly on decrease with small values of ?10% ? 0 while increase of RX5day (Maximum consecutive 5-day precipitation), SDII (Simple precipitation intensity index) and R20mm (Annual count of days when daily precipitation≥20 mm) are found in most areas with the values in the range of 0 ? 25%. Regional mean changes show that the linear trends are more significantly in temperature-related climate extremes compared with those in precipitation-related climate extremes. Comparing the two regions, greater uncertainty of the simulations in Xiongan New Area can be found, which indicates the deficiency of the model in local scale areas.
Grassland ecosystem is a complex social-ecological system. Permafrost, as an important factor to maintain the structure and function of alpine grassland ecosystem, is an important aspect to describe the ecological carrying capacity of alpine grassland objectively. The impact of permafrost on the ecological carrying capacity of alpine grassland is poorly understood. In this study, using the structural dynamics method, we established a numerical model to estimate the ecological carrying capacity of alpine grassland. Variation of the grassland ecological carrying capacity of the permafrost regions of the Qinghai-Tibetan Plateau (QTP) was analyzed, while the contribution of the permafrost active layer to the ecological carrying capacity of alpine grassland was also quantified. Results show that the ecological carrying capacity of alpine grassland in permafrost regions displayed an increasing trend, especially after 1998, due to increases of precipitation, air temperature, net primary productivity during growing season of grassland, and the establishment of ecological protection projects. The thickness variation of permafrost active layer is negatively correlated with ecological carrying capacity of alpine grassland. The mean contribution of permafrost active thickness to the ecological carrying capacity of alpine grassland was 10% in the QTP during 1980?2013. That is, for every 1 unit increase in the thickness of the permafrost active layer, the ecological carrying capacity of the alpine grassland will be reduced by 0.1 units. Owing to the significant spatial differences over the QTP and the uncertainty of climate change, this result is only a rough estimate of role of permafrost in the ecological carrying capacity.
Under the influence of climate change the reliable design and safe operation of hydraulic engineering has become a hot issue for decision makers, researchers and the public. Taking the Qingjiang River Basin as the research target, and using fuzzy set analysis method to classify the daily rainfall data generated under different greenhouse emission scenarios (e.g., A2, A1B and B1), the extreme precipitation series were simulated by generalized extreme value distribution (GEV) function. The results show that climate change has changed the precipitation structure, and its seasonal shift directly affects the flood season division. Under the three emission scenarios, the main flood season in the future will be postponed and shortened compared with the baseline period. The extreme precipitation in the future (e.g., 2011-2030, 2046-2065 and 2080-2099) is less than the baseline period, and this difference increases with the increase of the return period. The extreme precipitation in the main flood season is notably larger than that in the pre-flood season and post flood season. For extreme precipitation, the differences between periods are remarkably greater than those of emission scenarios.
With the awareness of global climate change and its possible consequences for humanity, climate resilience has become a key concept in our efforts to deal with the challenges induced by climate change. This paper describes and discusses the essences of the climate resilience concept and other existing key concepts that are closely linked to it with a focus on their interlinkages. Based on this theoretical discussion and a systematic assessment of the historical evolution of the resilience concept, a framework to implement climate resilience is presented. Although climate resilience entails different aspects for actors and priorities for different sectors and/or at different levels/scales, the generic nature of the framework should be useful for practices aiming at achieving climate resilience for different levels/scales/sectors. Finally, taking extreme climate resilience as an example, we further illustrate the application of the framework through reviewing the report entitled Resilience to Extreme Weather released by The Royal Society and analyzing the management framework of China’s response to extreme weather and climate disasters.
The adaptation of cryosphere change is a new research direction in the field of cryosphere science, and a typical representative of the interdisciplinary cross-integration research of natural and social sciences nowadays. The study on the adaptation of cryosphere changes in China, which started in 2007, has experienced a ten-year development. At present, the emphasis of the study has changed from the evaluation of vulnerability into the quantification of impacts of the cryosphere change with the improvement of knowledge level. The content of the study, including impacts, risks, vulnerability and adaptation of cryosphere change, is more perfect and systematic. The study method breaks through the shortcomings of the traditional index system weighting method and realizes the quantification preliminarily. The reasonable combination of research results of impacts, risks, vulnerability and adaptation in cryosphere change makes the adaptation measures of the cryosphere change more targeted. In the future, the existing theoretical system of the cryosphere changes adaptation in China should be expanded, improved and deepened, the coupling model of the cryosphere and the society economy should be constructed in order to scientifically quantify the effects of the change of the whole cryosphere elements, and a new research model involving different stakeholders and scientists should be established to cope with and adapt to the cryosphere changes and their effects.
As a potent greenhouse gas with high global warming potential, methane emission measurement and inventory are the major challenges for the oil and gas industry in China to achieve greenhouse gas emission control and reduction. In this paper, recommendations on greenhouse gas inventory were raised based on the comparison among various inventory methods worldwide, and the methane emission studies during oil and gas production. Suggestions were made to improve the greenhouse gas inventory based on the status quo of the oil and gas production in China. For fugitive methane emission, it is recommended to update the emission factor embracing the change in oil and gas production process, such as reduced flaring period, application of green well completion, and distinguish between onshore and offshore production, etc., and encourage oil and gas companies to update the methane emission factors based on component level calculations or actual measurements. Both top-down and bottom-up methods are encouraged during methane emission measurements so as to make the measurements verifiable and repeatable. It should be cautious to extrapolate the local-based measurements to regional or national levels.
To improve the estimation accuracy, a set of models based on ASIF (activity-modal structure-energy intensity-emission factor) methodology were established to evaluate the benefits of energy saving and emissions reduction from container handling equipment upgrades at port terminals, by introducing the ideas of life cycle assessment and cost benefit analysis. Next, the Ningbo-Zhoushan Port was taken for case study. The results show that the container handling equipment upgrades at Ningbo-Zhoushan Port can save 19.11 thousand tons of coal equivalent, reduce 61.75 thousand of tons of carbon dioxide, and cut 69.6 millions Yuan RMB of annual average cost. In addition, neglecting energy’s well-to-wheel (WTT) emissions would significantly affect the accuracy of CO2 emissions reduction, with a 8.65% of underestimation or a 40.83% of overestimation. The cost savings would be considerably overestimated by 59.63% without equipment upgrades cost but slightly underestimated by 2.30% without carbon trading cost. Moreover, the potentials of energy saving and CO2 emissions reduction are greatly influenced by container throughput, and the corresponding elasticity coefficients are larger than or equal to 1, respectively. The maximum potential of cost saving results from diesel’s price change, with a elasticity coefficient of 2.73. Consequently, the findings could provide technical support for evaluating the effect of port greening policies on energy saving and emissions reduction.
The negotiation on rule book of Paris Agreement faces challenges as soon as it was started. Nevertheless, the negotiation was generally done in Katowice climate conference by passing the rule book by which the rule-based climate regime is enhanced. Meanwhile, the rule book injects more attribution of ‘top-down’ to Paris Agreement which is characterized by ‘bottom-up’ and loose mechanisms, as a result the legal position of Paris Agreement is promoted. However, the conference also witnessed further separation of the climate world, shown as the union or re-grouping of negotiation groups, the degradation of major parties, arguments from interest groups, disagreements on latest sciences output. All these made no progress in ambition promotion. The road from Paris to Katowice shows we can’t simultaneously pursue governance efficiency, national self-determination, and global climate governance. Future negotiation should convert unified rules to real actions.
