The Humboldt upwelling system off the Peruvian coast is one of the most relevant regions for global fish catch. It undergoes strong natural variations on seasonal to decadal time scales which has been the focus of numerous studies before. Yet, the system’s response to climate change and, in particular, the time scale of emergence and potential tipping points are still debated. Here, we use a fully coupled Earth system model to constrain the time of emergence (ToE) of ocean physical and biogeochemical variables and assess their potential reversibility under different mitigation efforts employing a range of SSP scenario simulations. We find that the time of emergence in the Humboldt upwelling system is largely independent of the SSP scenario, since most variables have already emerged before the external forcing causes them to evolve in different directions. Our results further exhibit a clear chronology of ToEs across physical and biogeochemical variables with temperature emerging before plankton and nutrients, and oxygen and upwelling emerging later in the second half of the 21st century. We further find that the physical parameters in this region show signs of reversibility of their trend in scenarios with strong mitigation, indicative of not yet having reached a tipping point. While biogeochemical parameters also exhibit a strong reduction of the trend in the low emission scenarios, a reversal within this century is not definite.

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