Warming oceans are already chewing up the food chain:
Fish make up 17 percent of the global population’s intake of protein, and as much as 70 percent for people living in some coastal and island countries, according to the Food and Agriculture Organization of the United Nations.
As the oceans have warmed, some regions have been particularly hard-hit. In the northeast Atlantic Ocean and the Sea of Japan, fish populations declined by as much as 35 percent over the period of the study. “The ecosystems in East Asia have seen some of the largest decline in fisheries productivity,” Dr. Free said. “And that region is home to some of the largest growing human populations and populations that are highly dependent on seafood.”
And how soon will it be when national navies are deployed to escort fishing vessels so they can bring food home to the hungry masses? Vessels having their catch "confiscated" by cutters and frigates flying national (1st World) flags? That future is not as fictional as it sounds, if this trend continues: