Observations over the last 40 years show that the Atlantic Ocean salinity pattern has amplified, likely in response to changes in the atmospheric branch of the global water cycle. Observational estimates of oceanic meridional freshwater transport (FWT) at 26.5° N indicate a large increase over the last few decades, during an apparent decrease in the Atlantic Meridional Overturning Circulation (AMOC). However, there is limited observation based information at other latitudes. The relative importance of changing FWT divergence in these trends remains uncertain. Ten models from the Coupled Model Intercomparison Project Phase 5 are analysed for AMOC, FWT, water cycle, and salinity changes over 1950–2100. Over this timescale, strong trends in the water cycle and oceanic freshwater transports emerge, a part of anthropogenic climate change. Results show that as the water cycle amplifies with warming, FWT strengthens (more southward freshwater transport) throughout the Atlantic sector over the 21st century. FWT strengthens in the North Atlantic subtropical region in spite of declining AMOC, as the long-term trend is dominated by salinity change. The AMOC decline also induces a southward shift of the Inter-Tropical Convergence Zone and a dipole pattern of precipitation change over the tropical region. The consequent decrease in freshwater input north of the equator together with increasing net evaporation lead to strong salinification of the North Atlantic sub-tropical region, enhancing net northward salt transport. This opposes the influence of further AMOC weakening and results in intensifying southward freshwater transports across the entire Atlantic.

在过去40年中的观察表明，大西洋盐度模式已经放大，可能是由于全球水循环中大气分支的变化所致。在26.5°N处对海洋子午线淡水运输（FWT）的观测估计表明，在过去的几十年中，大西洋子午线翻转环流（AMOC）明显减少。但是，在其他纬度上基于观测的信息有限。在这些趋势中改变FWT差异的相对重要性仍然不确定。分析了耦合模型比较项目第5阶段的十个模型的AMOC，FWT，水循环和盐度在1950年至2100年之间发生变化。在这段时间内，水循环和海洋淡水运输出现了强烈的趋势，这是人为气候变化的一部分。结果表明，随着水循环随着变暖而放大，在21世纪，FWT在整个大西洋地区均得到加强（更多的向南淡水运输）。尽管AMOC下降，但北大西洋亚热带地区的FWT仍在增强，因为长期趋势是盐度变化所主导。该AMOC下降还导致热带收敛带向南移动，热带地区降水变化的偶极格局。因此，赤道以北的淡水输入量减少，加上净蒸发量增加，导致北大西洋亚热带地区强烈盐碱化，从而增强了北向净盐分的输送。这与AMOC进一步减弱的影响相抵触，并导致整个大西洋向南的淡水运输加剧。