Since the beginning of the Industrial Revolution, the pH of the oceans has dropped from 8.0 to 7.9. What's the big deal?
"We have changed the acidification of the ocean more in the past 150 years than it changed, in best we can tell, in about 100,000 years. So the critters, again a technical term, have gone and evolved to living in a pH of 8. All of a sudden, in just like "bang," in terms of evolution, we have shifted the environment." - Admiral Titley
If that turns out bad (and there is evidence it already is) there will be a billion people who currently rely on the oceans as a source of protein stressing agricultural resources. And those agricultural resources are no longer as predictable because of changes in rain patterns and water resources. Competition for natural resources at the national survival level drives nations to kinetic conflict. So there will be two reasons to respond: famine and war. Both demand scarce assets. Our nation's current role in the world demands our involvement. Or, we forfeit that role and the moral advantage it potentially provides. And so begins a downward spiral that ends up with our motivation in all commerce as base as survival interests. And that is not the America we know and love; the values we hold dear.