2/3 Like with the polycrisis, the different threats overlap and mutually reinforce, tragically. This is especially so for the threat to the oceans. The crossing of the oceanacidification boundary is actually far worse than it looks...

3/3 - because of the simultaneous ocean overheating, plastic pollution and sewage etc pollution. Together this makes a cocktail of effects that are mortally threatening to the oceans, and so to extremely basic features of a future such as, erm, adequate atmospheric oxygen levels.