The World Ocean is rapidly changing, with global and regional modification of temperature and salinity, resulting in widespread and irreversible impacts. While the most pronounced observed temperature and salinity changes are located in the upper ocean, changes in water masses at depth have been identified and will probably strengthen in the future. Here, using 11 climate models, we define when anthropogenic temperature and salinity changes are expected to emerge from natural variability in the ocean interior along density surfaces. The models predict that in 2020, 20–55% of the Atlantic, Pacific and Indian basins have an emergent anthropogenic signal; reaching 40–65% in 2050 and 55–80% in 2080. The well-ventilated Southern Ocean water masses emerge very rapidly, as early as the 1980–1990s, while the Northern Hemisphere water masses emerge in the 2010–2030s. Our results highlight the importance of maintaining and augmenting an ocean observing system capable of detecting and monitoring persistent anthropogenic changes.

世界海洋正在迅速变化，全球和区域对温度和盐度的改变，造成了广泛而不可逆的影响。尽管观测到的最明显的温度和盐度变化位于上层海洋，但已经确定了深处水团的变化，并且将来可能会增强。在这里，我们使用11个气候模型定义何时预计人为温度和盐度变化会因沿密度表面的海洋内部自然变化而出现。这些模型预测，到2020年，大西洋，太平洋和印度洋盆地中有20-55％会出现人为信号。到2050年达到40-65％，到2080年达到55-80％。通风良好的南大洋水域出现得非常快，早在1980-1990年代，而北半球的水团出现在2010-2030年代。我们的结果突出了维护和增强能够探测和监测持续的人为变化的海洋观测系统的重要性。