THE OCEANS ARE so vast and deep that until fairly recently, it was widely assumed that no matter how much trash and chemicals humans dumped into them, the effects would be negligible.

Today, we need look no further than the New Jersey-size dead zone that forms each summer in the Gulf of Mexico, or the thousand-mile-wide belt of plastic trash in the northern Pacific Ocean to see that this early “policy” placed a once flourishing ocean ecosystem on the brink of collapse.

The London Convention, ratified in 1975 by the United States, was the first international agreement to spell out better protection for the marine environment. The agreement implemented regulatory programs and prohibited the disposal of hazardous materials at