Soo.. overfishing + nuclear contamination to fisheries + global warming + other radioactive environmental damage = less significant? What if we throw in a massive Gulf oil spill? Kind of a crappy argument to claim that because X is worse, Y + X is less significant.
I'll answer your question; massive releases of nuclear contaminants into the environment will raise the number of cancers, birth defects and other health issues that are related to radioactive contamination and lower the environment's (already stressed) ability to supply quality foodstuffs.
Again, I'd like to point out that "we" (the general population of the world) are not responsible for the bulk of the environmental damage that has happened or is happening. "We" don't control/make decisions for Tepco, BP, Monsanto, etc., etc. Those sublimely paid, decision-making executives are responsible and should be held directly accountable for their actions. And how much environmental damage do you think the war machine causes? (Cue: sock puppets.) That's not "we" either. You'll know who "we" are when you're inside a FEMA camp!
Back to the cute kitten videos.....