Sea level in the South Atlantic Ocean has only been measured at a small number of tide‐gauge locations, which causes considerable uncertainty in 20th‐century sea‐level trend estimates in this basin. To obtain a better‐constrained sea‐level trend in the South Atlantic Ocean, this study aims to answer two questions. The first question is: can we combine new observations, vertical land motion estimates, and information on spatial sampling biases to obtain a likely range of 20th‐century sea‐level rise in the South Atlantic? We combine existing observations with recovered observations from Dakar and a high‐resolution sea‐level reconstruction based on salt‐marsh sediments from the Falkland Islands and find that the rate of sea‐level rise in the South Atlantic has likely been between 1.1 and 2.2 mm year⁻¹ (5%–95% confidence intervals), with a central estimate of 1.6 mm year⁻¹. This rate is on the high side, but not statistically different compared to global‐mean trends from recent reconstructions. The second question is: are there any physical processes that could explain a large deviation from the global‐mean sea‐level trend in the South Atlantic? Sterodynamic (changes in ocean dynamics and steric effects) and gravitation, rotation, and deformation effects related to ice mass loss and land water storage have probably led to a 20th‐century sea‐level trend in the South Atlantic above the global mean. Both observations and physical processes thus suggest that 20th‐century sea‐level rise in the South Atlantic has been about 0.3 mm year⁻¹ above the rate of global‐mean sea‐level rise, although even with the additional observations, the uncertainties are still too large to distinguish a statistically significant difference.

中文翻译：

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限制南大西洋20世纪海平面上升

南大西洋的海平面仅在少数潮汐仪位置进行了测量，这对该盆地的20世纪海平面趋势估计造成了很大的不确定性。为了获得更好地限制南大西洋海平面趋势的方法，本研究旨在回答两个问题。第一个问题是：我们能否结合新的观测资料，垂直的陆地运动估计值以及有关空间采样偏差的信息来获得南大西洋20世纪海平面上升的可能范围？我们将现有观测资料与达喀尔的观测资料相结合，并基于福克兰群岛的盐沼沉积物进行高分辨率海平面重建，发现南大西洋海平面上升的速度可能在1.1至2.2毫米之间年^-1（置信区间为5％–95％），中心估计为1.6 − ^1年。这个比率偏高，但与最近重建的全球平均趋势相比，没有统计学差异。第二个问题是：是否有任何物理过程可以解释与南大西洋全球平均海平面趋势有很大偏差的原因？与冰质流失和土地蓄水有关的恒流动力学（海洋动力学和空间效应的变化）以及引力，旋转和变形效应可能导致了南大西洋20世纪海平面趋势高于全球平均水平。因此，观测和物理过程都表明，南大西洋20世纪的海平面上升约为0.3 mm年^-1 尽管有其他观察结果，但仍高于全球平均海平面上升速度，但不确定性仍然太大，无法区分出统计学上的显着差异。