The seas are not alright: "Unusual warmth" hits nearly all of world's oceans

Relatedly, higher co2 levels is increasing the level of co2 of our oceans (surprise) and co2 is acidic, leading to (not only less oxygen) the death of anything that uses calcium carbonate (a base) to create some sort of structure.

So not only are they getting hotter, they're dissolving and asphyxiating - potentially collapsing entire ecosystems.

The Sixth Exctinction is rather morose...