It is pretty-well established that oceans are most productive at the poles, where the cold water is rich in nutrients. However, I'm not sure how much of that is due to our planet's current condition with ice at the poles. Are polar oceans good for plankton blooms because of the icehouse conditions?

Based on this, how would ocean productivity have been different when there was no ice at the poles? Would polar oceans be less productive?

sorry no-one seems to know the answer to your question.