Temperature drives global ocean patterns of biodiversity, shaping thermal niches through thresholds of thermal tolerance. Global warming is predicted to change thermal range bounds, yet research has primarily focused on temperature at the sea surface, while knowledge of changes through the depths of the water column is lacking. Here, using daily observations from ocean sites and model simulations, we track shifts in ocean temperatures, focusing on the emergence of thermal ranges whose future lower bounds exceed current upper bounds. These emerge below 50 m depth as early as ~2040 with high anthropogenic emissions, yet are delayed several decades for reduced emission scenarios. By 2100, concomitant changes in both lower and upper boundaries can expose pelagic ecosystems to thermal environments never experienced before. These results suggest the redistribution of marine species might differ across depth, highlighting a much more complex picture of the impact of climate change on marine ecosystems.

温度驱动生物多样性的全球海洋模式，通过耐热性阈值塑造热生态位。全球变暖预计会改变热范围界限，但研究主要集中在海面温度，而缺乏对水柱深处变化的了解。在这里，我们使用来自海洋站点的日常观测和模型模拟，跟踪海洋温度的变化，重点关注未来下限超过当前上限的温度范围的出现。这些早在 2040 年左右出现在 50 m 深度以下，人为排放量很高，但为了减少排放情景而推迟了几十年。到 2100 年，上下边界的伴随变化会使远洋生态系统暴露于前所未有的热环境中。