Then we're fucked, because (as the article notes) the melting is already baked in from current carbon emissions, and in any case all evidence is that our specie

Then we're fucked, because (as the article notes) the melting is already baked in from current carbon emissions, and in any case all evidence is that our species is not going to stop doing that. In practice, phytoplankton is not going to go extinct overnight. People underestimate the resilience of evolution. Maybe 95% of phytoplankton might go extinct overnight, but the survivors (by definition) will be adapted to the new, less salty ocean currents. So then we get planet-scale algal and fungal blooms, and we should be asking ourselves "What then?" Maybe we'll want to harvest algae and make food out of it, or maybe we want to get the hell away from coastlines. The jet stream's probably going to shut down, so all those folks in Northern Europe may want to consider evacuating to Africa. The point is to adapt to the world as it is rather than the world as we wish it to be or as we remember it. People who do that will survive and pass on their genes, and people who don't will die and drop out of history.