So, think this through with me.
Firstly, let’s assume that evolutionary history consists of nearly infinite numbers of generations.
“Gunfights,” in which inter-species and intra-species competition kills nearly everything alive, followed by massive repopulation, followed by more gunfights, average a lesser quantity of living gene replicas at any given moment in time, although any given gene might do better.
So perhaps, over the very long haul, you’d seen genetic strategies involving trying to stay way from gunfights and head towards maximum quantity of living gene-copies. Breed, and breed, and breed, and give ground rather than stand and fight. And slowly the world would fill up with stuff.
I think that’s what we’re eating in the oceans. An efficient, “maximum living matter” co-evolution of species.
Now, the question: if these systems collapse, then what? Well, the obvious answer is low productivity until co-evolution again restores the “full” ecosystem.
I do not believe that global warming is enough to do this.
Planet’s been warmer, planet’s been cooler, life goes on.
But hauling all of that biomass out of the sea and eating it?
Hm. I wonder, I really do, if stocks-and-flows models of biomass exchange aren’t actually where the rubber meets the road. Any living or just-dead matter is pretty much the same – something will eat it presently if it stops fighting back – but moving gigatons of biomass from one system to another, like cutting down forests and moving the timber, or slash and burn, or fishing…
I don’t know. Just a hunch, an intuition, that it’s much more important than global warming will turn out to be.