Whether you're a fan of seafood, biodiversity, natural wonders, or simply keeping the planet livable this should concern you:
"Oxygen levels in the world’s oceans have already dropped more than 2 percent between 1960 and 2010, and they are expected to decline up to 7 percent below the 1960 level over the next century."
https://e360.yale.edu/features/as-ocean-oxygen-levels-dip-fish-face-an-uncertain-future