IPCC AR6 Synthesis Report LR Figure 3.4 (a): Sea level rise: observations and projections 2020-2100, 2150, 2300 (relative to 1900)

Global mean sea level change in metres relative to 1900. The historical changes (black) are observed by tide gauges before 1992 and altimeters afterwards. The future changes to 2100 and for 2150 (coloured lines and shading) are assessed consistently with observational constraints based on emulation of CMIP, ice-sheet, and glacier models, and median values and likely ranges are shown for the considered scenarios. Relative to 1995–2014, the likely global mean sea level rise by 2050 is between 0.15–0.23 m in the very low GHG emissions scenario (SSP1-1.9) and 0.20– 0.29 m in the very high GHG emissions scenario (SSP5-8.5); by 2100 between 0.28–0.55 m under SSP1-1.9 and 0.63– 1.01 m under SSP5-8.5; and by 2150 between 0.37–0.86 m under SSP1-1.9 and 0.98–1.88 m under SSP5-8.5 (medium confidence). Changes relative to 1900 are calculated by adding 0.158 m (observed global mean sea level rise from 1900 to 1995–2014) to simulated changes relative to 1995–2014. The future changes to 2300 (bars) are based on literature assessment, representing the 17th–83rd percentile range for SSP1-2.6 (0.3–3.1 m) and SSP5-8.5 (1.7–6.8 m). Red dashed lines: Low-likelihood, high-impact storyline, including ice sheet instability processes. These indicate the potential impact of deeply uncertain processes, and show the 83rd percentile of SSP5-8.5 projections that include low-likelihood, high impact processes that cannot be ruled out; because of low confidence in projections of these processes, this is not part of a likely range.

相对于1900年的全球平均海平面变化（单位：米）。历史变化（黑色曲线）的观测数据：1992年前采用验潮仪获取，1992年后采用卫星高度计获取。针对2100年及2150年的未来变化（彩色线条及阴影区），基于耦合模式比较计划（CMIP）、冰盖及冰川模型的仿真结果，并结合观测约束开展一致性评估，针对所考虑的排放情景给出了中位数及可信区间。以1995-2014年为基准，在极低温室气体排放情景（SSP1-1.9）下，预计到2050年全球平均海平面上升的可信区间为0.15~0.23米；在极高温室气体排放情景（SSP5-8.5）下则为0.20~0.29米。到2100年，SSP1-1.9情景下的可信区间为0.28~0.55米，SSP5-8.5情景下为0.63~1.01米；到2150年，SSP1-1.9情景下为0.37~0.86米，SSP5-8.5情景下为0.98~1.88米（置信度中等）。相对于1900年的海平面变化量，通过将以1995-2014年为基准的模拟变化量加上0.158米（1900年至1995-2014年间观测到的全球平均海平面上升值）计算得到。针对2300年的未来变化（柱状图）基于已发表文献评估得到，对应SSP1-2.6情景下17%~83%百分位数区间（0.3~3.1米）以及SSP5-8.5情景下17%~83%百分位数区间（1.7~6.8米）。红色虚线：代表低可能性、高影响的情景路径，包含冰盖不稳定性过程。该类情景反映了深度不确定过程的潜在影响，展示了纳入无法排除的低可能性、高影响过程的SSP5-8.5情景投影的83%百分位数结果；由于对该类过程的投影置信度较低，因此未纳入可信区间范围。