The articles you link say that it's not exclusively due to climate change (which is a superset of ocean warming), that doesn't mean climate change is a negligib

The articles you link say that it's not exclusively due to climate change (which is a superset of ocean warming), that doesn't mean climate change is a negligible contributor to the problem. And as the temperatures rise its contribution may rise. In fact the second article itself says that climate change directly causes some of that N:P imbalance.