| 摘要: |
| 人类活动引起的当代气候变暖已导致全球海平面显著上升，在21世纪全球气候继续变暖的背景下，东南沿海海平面的升高将对区域环境及社会可持续发展带来巨大挑战，但目前对未来区域海平面变化的预估尚存在较大的不确定性。本文基于筛选的国际耦合模式比较计划第5阶段（CMIP5）的10个模拟性能较好的气候模式输出结果，通过多模式集合预估了未来温室气体三种排放情景下21世纪东海和南海区域海平面高度的趋势变化，并分析了不同影响因子的贡献。通过计算海水热比容、盐比容和动力因子对海平面高度的影响，并在考虑冰川冰盖消融等因子的订正后，发现：21世纪东海和南海海平面高度都呈现连续上升趋势，东海和南海地区上升幅度略小于全球平均，南海上升幅度略大于东海。在温室气体低（RCP2.6）、中（RCP4.5）和高（RCP8.5）排放情景下，21世纪后期（2081—2100年）较前期（2006—2025年）东海/南海平均海平面分别上升0.26 [0.01—0.55] m/0.29 [0.05—0.55] m、0.38 [0.10—0.66] m/0.40 [0.14—0.67] m和0.52[0.15—0.89] m/0.52[0.23—0.83] m（方括号内为相应的不确定性范围）。随着温室气体排放的升高，海平面上升幅度也增大，东海海平面上升区由东南向西北扩展，南海海平面上升区由东北向西南扩展。统计分析还表明：在不同排放情景下，不同影响因子对海平面变化的贡献也不一样，随着排放强度从低到高变化，海洋比容加动力因子的相对贡献从28%—34%升高至46%—47%，而冰川冰盖消融等其他因子的相对贡献从 66%—72%降低至53%—54%。 |
| 关键词: 气候变暖 海平面高度 东海 南海 CMIP5 |
| DOI：10.7515/JEE202003 |
| CSTR：32259.14.JEE202003 |
| 分类号: |
| 基金项目:国家自然科学基金项目（41991254，41690115） |
| 英文基金项目:National Nature Science Foundation of China (41991254, 41690115) |
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| Projection of the 21st century sea level change in East China Sea and South China Sea based on CMIP5 model results |
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LIU Rui, LIU Xiaodong, LIU Heng
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1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Xi’an Institute for Innovative Earth Environment Research, Xi’an 710061, China
4. National Earth System Science Data Center, National Science & Technology Infrastructure of China, Beijing 100101, China
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| Abstract: |
| Background, aim, and scope As an important design indicator and safety parameter for engineering projects, sea levels have significantly risen in the past decades with global warming and increasing impact of human activities. In the context of global warming in the 21st century, the rate of sea level rise is expected to increase further in the future. This situation will pose great challenges to regional environments and the sustainable development of society in the southeast coastal areas of China. Therefore, projecting future sea level changes in the East China Sea and South China Sea has become an important scientific issue with practical significance. Materials and methods This study uses the results of 34 climate models from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) to select 10 models with good performance in simulating temperature and precipitation trends and patterns worldwide and in central-eastern China, projected trends and distributions of 21st century sea level changes in the East and South China seas under low (RCP2.6), medium (RCP4.5) and high (RCP8.5) greenhouse gas emission scenarios, and analyzes the contributions of thermosteric, halosteric, and dynamic factors. In addition, the effects of glacial and ice sheet melting and other factors on sea level rise are estimated according to the IPCC Fifth Assessment Report. Results When only steric sea level (including thermosteric sea level and halosteric sea level) and dynamic sea level changes are considered, the sea level of the East China Sea are projected to rise by 0.07 [−0.01—0.16] m, 0.15 [0.08—0.23] m and 0.24 [0.10—0.38] m in 2081—2100 compared with 2006—2025, and projected rise estimates in the South China Sea are 0.09 [0.03—0.16] m, 0.17 [0.11—0.24] m and 0.25 [0.17—0.33] m, under the RCP2.6, RCP4.5, and RCP8.5 emissions scenarios, respectively (ranges in the square brackets represent the uncertainties). Sea level rise projections due to factors related to glacial and ice sheet melting reach 0.19 [0.01—0.39] m, 0.22 [0.02—0.43] m, and 0.28 [0.05—0.52] m under the three emissions scenarios. Discussion Thermosteric, halosteric, and dynamic sea levels are all projected to increase throughout the 21st century under the three future emissions scenarios. Melting of glaciers and ice sheets is also an important contributor to sea level rise. Under the medium emissions scenario, the contribution of the steric plus dynamic factors is 41%—44%, while that of other factors including glacier and ice sheet melt is 55%—58%. Their relative contributions seem to change with emission intensity. Conclusions In the 21st century, sea levels in the East and South China seas will continue to rise, although within a slightly smaller range than the global average. Projected increases in the South China Sea are slightly larger than those in the East China Sea. Considering the effects of thermosteric, halosteric, and dynamic sea level changes, as well as glacier and ice sheet melting-induced sea level changes, the total sea level rise in the East China Sea for 2081—2100 compared with 2006—2025 is projected to be 0.26 [0.01—0.55] m, 0.38 [0.10—0.66] m, and 0.52 [0.15—0.89] m, and results for the South China Sea are 0.29 [0.05—0.55] m, 0.40 [0.14—0.67] m, and 0.52 [0.23—0.83] m, under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. Recommendations and perspectives This study uses the multi-model ensemble method to project regional sea level changes to reduce errors from a single model to a certain extent and improve the reliability of the projection results. However, due to the influence of many complex factors, there are still some uncertainties in our projection results. Therefore, further studies are needed in the future. |
| Key words: climate warming sea level East China Sea South China Sea CMIP5 |
