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At the beginning of 21st century, a study suggested that Northwest China’s climate is becoming warmer and more humid. However, there were doubts about this conclusion because the humidification changes on a small scale only last for a short period, and also suspicions about the development, duration, and impact of the warming-wetting trend in this region. This paper sets out several factors, such as the area, intensity of humidification, and comprehensiveness of the wetness index, to characterize the wetting degree. Furthermore, by using measured climate data, CRU data, climate scenario predictions, and ecological and hydrological data, we systematically analyze temporal and spatial evolution of the warming-wetting trend in Northwest China. Studies have shown that Northwest China has experienced two warming periods during the last century, i.e., the 1940s, and the period from the 1960s to the present (the current warming period). The latter is more substantial. The precipitation in the west and east part of Northwest China has a seesaw change process in many periods. However, humidification has simultaneously occurred in both regions since the beginning of this century. The current precipitation in the west part of Northwest China has far exceeded any period over the past 100 a. In contrast, the east part’s recent rainfall is still currently lower than that of the 1950s and 1960s. Since 1961, Northwest China’s west region has experienced consistent humidification, which has been more pronounced since 1987. Simultaneously, the east part was drying from 1961 to 1997, and has become humid since 1997. The temperature, precipitation, and aridity index changes in the west part show the same patterns. In most periods, the west part was either cold-dry or warm-wet. In comparison, such consistency of the temperature, precipitation, and aridity changes does not exist in the east region. Before this century, warm-wet climates rarely occurred in the east region, having become more frequent. This is probably due to the different dominant temperatures and precipitation processes in the west and east regions. From a spatial point of view, the temperature increases in the whole of Northwest China, and the precipitation increases in the west region and decreases in the east region. The area with increasing rainfall has become larger during the past three climatic periods, and currently covers the whole of Northwest China. The precipitation, aridity index, and comprehensive humidity index in Northwest China have a non-linear increasing trend. The expanding humidity trend has been significant since the beginning of this century. The current warming and humidification have not changed the basic climate pattern in Northwest China. However, if the current trend continues, they would change the climate pattern in the future. Such climate change may result from the simultaneous enhancement of the westerly circulation and the East Asian summer monsoon circulations in this century. The climate warming and humidification in Northwest China significantly impacted extreme weather events, water resources, ecological environment, and agriculture during this century. This research will provide a basis for decision-making on issues such as implementing the Western development strategy in the new era, the ecological protection and high-quality development of the Yellow River Basin, environmental construction planning, and water resources management policies in Northwest China.

During the second half of the 20th century, eastern Northwest China experienced a warming and drying climate change. To determine whether this trend has continued or changed during the present century, this study systematically analyzes the characteristics of warming and dry–wet changes in eastern Northwest China based on the latest observational data and World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 6 (CMIP6) collection data. The results show that eastern Northwest China has warmed continuously during the past 60 years with a sudden temperature change occurring in the late 1990s. However, the temperature in the 2000s decreased slowly, and that in the 2010s showed a warming trend. The amount of precipitation began to increase in the late 1990s, which indicates a contemporary climate transition from warm-dry to warm-wet in eastern Northwest China. The contribution of precipitation to humidity is significantly more than that of temperature. Long-term and interannual variations dominate the temperature change, with the contribution of the former much stronger than that of the latter. However, interannual variation dominates the precipitation change. The warming accelerates from period to period, and the temperature spatial consistently increased during the three most recent climatic periods. The precipitation decreased from 1961–1990 to 1981–2010, whereas its spatial consistency increased from 1981–2010 to 1991–2019. The significant warming and humidification that began in the late 1990s and is expected to continue until the end of the 21st century in the medium emission scenario. However, the current sub-humid climate will not easily be changed. The warming could cause a climate transition from warm temperate to subtropical by 2040. The dry-to-wet climate transition in eastern Northwest China could be related to synergistic enhancement of the East Asian summer monsoon and the westerly circulation. This research provides a scientific decision-making basis for implementing western development strategies, ecological protection, and high-quality development of the Yellow River Basin Area as well as that for ecological construction planning and water resource management of eastern Northwest China.

Jiang, C.; Wang, J.; Zhang, P.; Wang, Y.; Guo, X., and Zhu, L., 2020. Impact of rapid salinity variation on aquaculture organisms caused by water drainage from an estuary sluice. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 39–42. Coconut Creek (Florida), ISSN 0749-0208.Salinity is one of the most important factors affecting the survival and distribution of estuarine organisms. The construction of an estuarine gate will change the salinity of seawater and produces a direct impact on marine ecosystems. The variation of salinity and its influence on aquaculture organisms in the Yueqing Bay were revealed by on-site monitoring and comparative analysis during the flood water discharge period of the Jiangxia Drainage Project. The results showed that salinity declined rapidly after the sluice was opened, and the decreasing amplitude and duration were related to the intensity and lasting time of water drainage, as well as the distance to the gate. The seawater salinity could fall to 4‰ in an area where it is close to the gate. During neap tide, salinity's change along the waterway is greater and recovery time is longer than spring tide. Most of aquaculture organisms have limited tolerance to low salinity and its rapid variation. The decrease extent of seawater salinity often exceeds 10‰ during the drainage period, which is unbearable to Sinonovacula constricta and Scylla serrata, etc. Therefore, the construction of estuary sluice and water drainage will affect the growth and survival of marine life.

Increasing global temperatures and frequency of low precipitation have made drought a major natural disaster around the world. Drought is a major threat to China's food security. Thus, the recent abnormal characteristics of Chinese droughts warrant further study. We therefore examined daily air temperature and precipitation from 1961 to 2014 at 572 Chinese meteorological stations. We used an improved version of Meteorological Drought Composite Index (MCI) as a drought indicator to analyze the spatial variation and temporal changes of the drought severity, frequency, duration, and location. China's drought-affected area has expanded, and the severity and frequency have increased due to climate warming. The drought-affected areas are also changing, with drought intensifying in the north but increasing even more in the south, especially for severe drought. Drought was most widespread and sustained in the late 1990s and early 2000s, primarily in the southern Yellow River Basin and the northern Yangtze River Basin. Frequency analysis revealed >30% drought frequency (% of total years) in the western and eastern parts of northwestern China and in eastern, northern, and southwestern China. Drought frequency was higher in the Yangtze River and Yellow River basins. China's drought intensity, duration, and frequency were generally higher in the north and east than in the south and west; however, these parameters increased more rapidly in the south. Droughts occurred year-round in China, but the occurrence, range, duration, and frequency differed among years and regions. Our results offer insights into the development of drought in China and provide support for disaster risk assessment and response planning.