the known consequences of polluting the the entire base of the planets food web isn't existential? "scientists", politicians, beurocrats, lawyers, and the mega wealthy have kept moving the agread upon limits to environmental exploitation, with zero sign that they have any other intent, than to take more³ what you are missing is that no one will ask for permission, to fix that.

I had hoped the use of the word was based on some actual specific world-ending effect I didn't know about, so I could learn something new and important. But apparently it's just untethered anxiety.

We’ve literally been dumping nuclear and chemical waste in the oceans for 100 years now?

It isn’t good, but it isn’t any different than usual either.

The amount of plastic going into the ocean is increasing rapidly, especially in the last 15 years or so. It is different from (say) 50 years ago.

Also you might have noticed that a lot of sea life is scarcer than it used to be.