How do think that saving the oceans can feed the world?

If you mean like saving the oceans as making it fresh then saving the oceans will give much much more fresh water to drink and that way you are feeding the world.

(Sorry if it is wrong, but this might just be the answer)( Most likely it is correct)

a mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. this uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.a geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.