Exploratory Extended Time-mean Sea Level Projections to 2300 (cm)

Please note this dataset supersedes previous versions on the Climate Data Portal. It has been uploaded following an update to the dataset in March 2023. This means sea level rise is approximately 1cm higher (larger) compared to the original data release (i.e. the previous version available on this portal) for all UKCP18 site-specific sea level projections at all timescales. For more details please refer to the technical note. What does the data show? The exploratory extended time-mean sea-level projections to 2300 show the amount of sea-level change (in cm) for each coastal location (grid-box) around the British Isles for several emission scenarios. Sea-level rise is the primary mechanism by which we expect coastal flood risk to change in the UK in the future. The amount of sea-level rise depends on the location around the British Isles and increases with higher emission scenarios. Here, we provide the relative time-mean sea-level projections to 2300, i.e. the local sea-level change experienced at a particular location compared to the 1981-2000 average, produced as part of UKCP18. For each grid box the time-mean sea-level change projections are provided for the end of each decade (e.g. 2010, 2020, 2030 etc) for three emission scenarios known as Representative Concentration Pathways (RCP) and for three percentiles. The emission scenarios are: RCP2.6 RCP4.5 RCP8.5 The percentiles are: 5th percentile 50th percentile 95th percentile Important limitations of the data We cannot rule out substantial additional sea-level rise associated with ice sheet instability processes that are not represented in the UKCP18 projections, as discussed in the recent IPCC Sixth Assessment Report (AR6). These exploratory projections show sea levels continue to increase beyond 2100 even with large reductions in greenhouse gas emissions. It should be noted that these projections have a greater degree of uncertainty than the 21st Century Projections and should therefore be treated as illustrative of the potential future changes. They are designed to be used alongside the 21st Century projections for those interested in exploring post-2100 changes. What are the naming conventions and how do I explore the data? The data is supplied so that each row corresponds to the combination of a RCP emissions scenario and percentile value e.g. 'RCP45_50' is the RCP4.5 scenario and the 50th percentile. This can be viewed and filtered by the field 'RCP and Percentile'. The columns (fields) correspond to the end of each decade and the fields are named by sea level anomaly at year x, e.g. '2050 seaLevelAnom' is the sea level anomaly at 2050 compared to the 1981-2000 average. Please note that the styling and filtering options are independent of each other and the attribute you wish to style the data by can be set differently to the one you filter by. Please ensure that you have selected the RCP/percentile and decade you want to both filter and style the data by. Select the cell you are interested in to view all values. To understand how to explore the data please refer to the user guide. What are the emission scenarios? The 21st Century time-mean sea level projections were produced using some of the future emission scenarios used in the IPCC Fifth Assessment Report (AR5). These are RCP2.6, RCP4.5 and RCP8.5, which are based on the concentration of greenhouse gases and aerosols in the atmosphere. RCP2.6 is an aggressive mitigation pathway, where greenhouse gas emissions are strongly reduced. RCP4.5 is an intermediate ‘stabilisation’ pathway, where greenhouse gas emissions are reduced by varying levels. RCP8.5 is a high emission pathway, where greenhouse gas emissions continue to grow unmitigated. Further information is available in the Understanding the data page and the RCP Guidance on the UKCP18 website. What are the percentiles? The UKCP18 sea-level projections are based on a large Monte Carlo simulation that represents 450,000 possible outcomes in terms of global mean sea-level change. The Monte Carlo simulation is designed to sample the uncertainties across the different components of sea-level rise, and the amount of warming we see for a given emissions scenario across CMIP5 climate models. The percentiles are used to characterise the uncertainty in the Monte Carlo projections based on the statistical distribution of the 450,000 individual simulation members. For example, the 50th percentile represents the central estimate (median) amongst the model projections. Whilst the 95th percentile value means 95% of the model distribution is below that value and similarly the 5th percentile value means 5% of the model distribution is below that value. The range between the 5th to 95th percentiles represent the projection range amongst models and corresponds to the IPCC AR5 “likely range”. It should be noted that, there may be a greater than 10% chance that the real-world sea level rise lies outside this range. Data source This data is an extract of a larger dataset (every year and more percentiles) which is available on CEDA at https://catalogue.ceda.ac.uk/uuid/a077f4058cda4cd4b37ccfbdf1a6bd29 Data has been extracted from the v20221219 version (downloaded 17/04/2023) of three files: seaLevelAnom_marine-sim_rcp26_ann_2007-2300.nc seaLevelAnom_marine-sim_rcp45_ann_2007-2300.nc seaLevelAnom_marine-sim_rcp85_ann_2007-2300.nc Useful links to find out more For a comprehensive description of the underpinning science, evaluation and results see the UKCP18 Marine Projections Report (Palmer et al, 2018). For a discussion on ice sheet instability processes in the latest IPCC assessment report, see Fox-Kemper et al (2021). Technical note for the update to the underpinning data: https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/research/ukcp/ukcp_tech_note_sea_level_mar23.pdf. Further information in the Met Office Climate Data Portal Understanding the data page.请注意本数据集取代了气候数据门户（Climate Data Portal）上的先前版本。本数据集于2023年3月完成更新后上传。这意味着，针对所有英国气候预测2018（UK Climate Projections 2018, UKCP18）的沿海站点海平面预测，在所有时间尺度下，海平面上升幅度均较本门户此前发布的初始版本高出约1厘米。如需了解更多详情，请参阅技术说明。 数据内容说明 本数据展示了截至2300年的探索性扩展时间平均海平面预测，涵盖不列颠群岛周边各沿海区域（网格单元）在多种排放情景下的海平面变化量（单位：厘米）。海平面上升是未来英国沿海洪涝风险变化的核心驱动机制。海平面上升幅度因不列颠群岛周边的地理位置而异，且随排放情景强度提升而增大。 此处我们提供了截至2300年的相对时间平均海平面预测，即相较于1981-2000年平均值，特定地点所经历的局地海平面变化，该数据集作为UKCP18的组成部分生成。针对每个网格单元，我们提供了各十年末（如2010年、2020年、2030年等）的时间平均海平面变化预测，涵盖三种被称为典型浓度路径（Representative Concentration Pathways, RCP）的排放情景，以及三个百分位数值。 排放情景包括：RCP2.6、RCP4.5、RCP8.5 百分位数值包括：第5百分位、第50百分位、第95百分位 数据重要局限性 我们无法排除UKCP18预测中未涵盖的冰盖不稳定过程引发的显著额外海平面上升，正如近期政府间气候变化专门委员会第六次评估报告（Intergovernmental Panel on Climate Change Sixth Assessment Report, AR6）中所讨论的那样。 这些探索性预测显示，即使温室气体排放量大幅减少，海平面仍将在2100年之后持续上升。需注意的是，相较于21世纪海平面预测，本预测的不确定性更高，因此仅应用于展示潜在的未来变化。本数据集专为希望探索2100年后变化的用户设计，可与21世纪海平面预测配套使用。 数据命名规则与浏览方式 本数据集的每行对应一种RCP排放情景与百分位数值的组合，例如"RCP45_50"代表RCP4.5情景与第50百分位数值。可通过"RCP与百分位"字段对数据进行查看与筛选。 各列（字段）对应各十年末的海平面距平，字段命名格式为“年份x 海平面距平”，例如"2050 seaLevelAnom"代表相较于1981-2000年平均值，2050年的海平面距平。 请注意，样式设置与筛选选项相互独立，可将数据样式化所依据的属性设置为与筛选所依据的属性不同。请确保已选择需要同时用于筛选和样式化的RCP/百分位数值与十年。点击感兴趣的网格单元即可查看所有对应数值。如需了解数据浏览的具体操作方法，请参阅用户指南。 排放情景说明 21世纪时间平均海平面预测采用了政府间气候变化专门委员会第五次评估报告（Intergovernmental Panel on Climate Change Fifth Assessment Report, AR5）中使用的部分未来排放情景，即基于大气中温室气体与气溶胶浓度的RCP2.6、RCP4.5和RCP8.5。 其中，RCP2.6为强减排路径，温室气体排放量将被大幅削减；RCP4.5为中等“稳定”路径，温室气体排放量将按不同幅度削减；RCP8.5为高排放路径，温室气体排放量将在无减排措施的情况下持续增长。 更多信息可参阅UKCP18官网的“了解数据”页面与RCP指南。 百分位数值说明 UKCP18的海平面预测基于大规模蒙特卡洛（Monte Carlo）模拟，该模拟涵盖了45万个全球平均海平面变化的可能结果。蒙特卡洛模拟旨在采样海平面上升各组成部分的不确定性，以及在给定排放情景下，跨耦合模型比对项目第五阶段（Coupled Model Intercomparison Project Phase 5, CMIP5）气候模型的预估增温幅度。 百分位数值用于基于45万个独立模拟成员的统计分布，表征蒙特卡洛预测的不确定性。例如，第50百分位代表模型预测的中心估计值（中位数）；第95百分位意味着95%的模型分布结果低于该值，同理，第5百分位意味着5%的模型分布结果低于该值。第5至第95百分位的区间代表模型间的预测范围，对应AR5中的“可能范围”。需注意的是，实际海平面上升超出该区间的概率可能超过10%。 数据来源 本数据集为更大规模数据集的子集（包含更多年份与百分位数值），完整数据集可在英国气候与环境数据中心（Centre for Environmental Data Analysis, CEDA）获取，链接为：https://catalogue.ceda.ac.uk/uuid/a077f4058cda4cd4b37ccfbdf1a6bd29 本数据从3个文件的v20221219版本（2023年4月17日下载）中提取得到，文件名分别为： seaLevelAnom_marine-sim_rcp26_ann_2007-2300.nc seaLevelAnom_marine-sim_rcp45_ann_2007-2300.nc seaLevelAnom_marine-sim_rcp85_ann_2007-2300.nc 更多了解渠道 如需了解支撑本数据集的科学原理、评估方法与结果详情，请参阅《英国气候预测2018沿海预测报告》（Palmer等，2018）。如需讨论最新IPCC评估报告中的冰盖不稳定过程，请参阅Fox-Kemper等（2021）。 本基础数据更新的技术说明：https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/research/ukcp/ukcp_tech_note_sea_level_mar23.pdf。 更多信息可参阅英国气象局气候数据门户的“了解数据”页面。