Climate change can drive shifts in the seasonality of marine productivity, with consequences for the marine food web. However, these alterations in phytoplankton bloom phenology (initiation and peak timing), and the underlying drivers, are not well understood. Here, using a 30-member Large Ensemble of climate change projections, we show earlier bloom initiation in most ocean regions, yet changes in bloom peak timing vary widely by region. Shifts in both initiation and peak timing are induced by a subtle decoupling between altered phytoplankton growth and zooplankton predation, with increased zooplankton predation (top-down control) playing an important role in altered bloom peak timing over much of the global ocean. Only in limited regions is light limitation a primary control for bloom initiation changes. In the extratropics, climate-change-induced phenological shifts will exceed background natural variability by the end of the twenty-first century, which may impact energy flow in the marine food webs.

气候变化可以推动海洋生产力的季节性变化，从而对海洋食物网产生影响。然而，浮游植物水华物候学（起始和高峰时间）的这些变化以及潜在的驱动因素尚不清楚。在这里，我们使用由 30 名成员组成的大型气候变化预测集合，展示了大多数海洋区域的较早开花开始，但开花高峰时间的变化因地区而异。改变的浮游植物生长和浮游动物捕食之间的微妙脱钩引起了开始和高峰时间的变化，增加的浮游动物捕食（自上而下控制）在全球大部分海洋的开花高峰时间改变中发挥重要作用。只有在有限的区域中，光限制才是开花开始变化的主要控制因素。在热带地区，