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Cake day: May 23rd, 2024

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  • Relevant passage:

    Applying our model to today’s atmosphere-ocean state with an enhanced anthropogenic P flux from land in a sustained 130% excess over average Phanerozoic continental P weathering rates will ultimately trigger the anoxia-P-dependent cascade again in a manner that locks the oceans into an extensively anoxic state for more than half a million years. The oceanic redox state passes a tipping point when the oceanic P/O2 ratio is ∼2.3 and continues into a eutrophic ocean state with 3.5 times higher P/O2 than today and sustained high productivity and organic C burial. The Earth system tips back into the oxic ocean state as atmospheric O2 levels rise and cause oceanic P/O2 ratio to decline below the tipping point (Figure 4). The dynamics of the event depend critically on the formulation of the anoxia function, which is assumed represented by a sigmoidal function with parameters calibrated in 3D (GENIE)64 and 1D (CANOPS)65 Earth System models. The new sedimentation-dependent formulation of the benthic P flux does make the oceans more sensitive towards runaway anoxia when anoxia develops in shallower depths, but our model still requires a long period (>104 years) of sustained P input to pass the tipping point for global marine anoxia today. With oceanic P input at a sustained 130% excess over average Phanerozoic continental P weathering rates for ∼120 ka, anthropogenic forcing will eventually trigger the anoxia-P-dependent cascade in a manner that locks the oceans into an extensively anoxic ocean state for more than 0.5 Ma until oceanic P/O2 begins to decline as a result of rising atmospheric O2 levels (Figure 4).






































  • Current renewables are fossil fuel multipliers. This is not a basic law of physics, but we’ve almost ran out of time and fossil resources to fix that. What’s worse is that we’re not even seriously attempting it.

    We’re not giving up fossil fuels, fossil fuels are (un)fortunately abandoning us. Which of course brings us to that apocalyptic scenario you mention.