Using hourly sea level data from four tide gauges, the changes of the extreme sea level in the Bohai Sea were analyzed in this work. Three components (i.e., mean sea level, tide and surge) as well as the tide–surge interaction were studied to find which component was important in the changes of extreme sea levels. Significant increasing trends exist in the mean sea level at four tide gauges from 1980 to 2016, and the increase rate ranges from 0.2 to 0.5 cm/year. The mean high tide levels show positive trends at four tide gauges, and the increasing rate (0.1 to 0.3 cm/year) is not small compared with the long-term trends of the mean sea levels. However, the mean tidal ranges show negative trends at Longkou, Qinhuangdao and Tanggu, with the rate from about −0.7 to −0.2 cm/year. At Qinhuangdao and Tanggu, the annual surge intensity shows explicit long-term decreasing trend. At all four tide gauges, the storm surge intensity shows distinct inter-annual variability and decadal variability. All four tide gauges show significant tide–surge interaction, the characteristics of the tide–surge interaction differ due to their locations, and no clear long-term change was found. Convincing evidence implies that the extreme sea levels increase during the past decades from 1980 to 2016 at all tide gauges, with the increasing rate differing at different percentile levels. The extreme sea level changes in the Bohai Sea are highly affected by the changes of mean sea level and high tide level, especially the latter. The surge variation contributes to the changes of extreme sea level at locations where the tide–surge interaction is relatively weak.

Li, W.; Xiang, W.; Wang, H.; Dong, J.; Xu, H.; Zhang, J.; Zuo, C.; Liu, Q.; Lv, J., and Xie, Q., 2023. Preliminary coastal vulnerability assessment for Guangdong province, Southeast China. Journal of Coastal Research, 39(3), 509–518. Charlotte (North Carolina), ISSN 0749-0208. Accelerating sea level rise and intensifying extreme marine and weather events pose unprecedented challenges to coastal areas in the context of climate change. As a hotspot of marine disasters, Guangdong has been suffering from severe marine disasters including storms, flooding, coastal erosion, and saltwater intrusion in the last decades. It is essential for coastal management authorities to distinguish vulnerable areas and optimize coastal planning. To help identify the coastal vulnerability patterns of the Guangdong coast, the coastal vulnerability index was used based on integrated physical and socio-economic indicators including relative sea level rise, mean tide range, significant wave height, coastal slope, geomorphology, population, land use, and coastal gross domestic product. Each indicator was assigned five vulnerability classifications from very low to very high (1–5). Results show that about 36.7% of the coastline in Guangdong is highly vulnerable, of which 18.3% of the coastline is very highly vulnerable. About 63.3% of the coastline is in moderate to low vulnerability. In particular, the coastal areas in east of Zhanjiang, Maoming, Yangjiang, Zhuhai, Zhongshan, Guangzhou, west of Shenzhen, east Shanwei, and Chaozhou are more vulnerable to sea level rise, which calls for urgent planning and protective measures.

Global warming has been altering the East Asian climate at an unprecedented rate since the 20th century. In order to evaluate the changes in the East Asian winter climate (EAWC) and support policy-making for climate mitigation and adaptation strategies, this paper utilizes the multimodel ensemble from the Couple Model Intercomparison Project 6 and a temperature threshold method to investigate the EAWC changes during the period 1979–2100. The results show that the EAWC has been undergoing widespread and robust changes in response to global warming. The winter length in East Asia has shortened and will continue shortening owing to later onsets and earlier withdrawals, leading to a drastic contraction in length from 100 days in 1979 to 43 days (27 days) in 2100 under SSP2-4.5 (SSP5-8.5). While most regions of the East Asian continent are projected to become warmer in winter, the Japan and marginal seas of northeastern Asia will face the risks from colder winters with more frequent extreme cold events, accompanied by less precipitation. Meanwhile, the Tibetan Plateau is very likely to have colder winters in the future, though its surface snow amounts will significantly decline. Greenhouse gas (GHG) emissions are found to be responsible for the EAWC changes. GHG traps heat inside the Earth’s atmosphere and notably increases the air temperature; moreover, its force modulates large-scale atmospheric circulation, facilitating an enhanced and northward-positioned Aleutian low together with a weakened Siberian high, East Asian trough, and East Asian jet stream. These two effects work together, resulting in a contracted winter with robust and uneven regional changes in the EAWC. This finding highlights the urgency of curbing GHG emissions and improving forecasts of the EAWC, which are crucial for mitigating their major ecological and social impacts.