The heat is on, and our oceans are suffering. Declining ocean productivity is the new concern.
Lost ocean productivity means less food for fish and other ocean animals. This scary problem comes from reduced upwelling and lower nutrient levels. Nutrients are the fertilizer that determines how much phytoplankton (tiny, free-floating ocean plants) can grow in the ocean. Upwelling is when water comes to the ocean surface from the dark, cold, nutrient-rich depths.
All of this from global warming that is making ocean surface waters warmer, and that strengthens ocean stratification--the development of pancake layers of ocean water that resist mixing because they have different temperatures and different densities. Sort of like a layer of oil floating on top of vinegar in salad dressing that needs a shake.
To make things worse, reduced ocean productivity means oceans can't absorb as much CO2, so this is a feed-forward cycle that might worsen global warming-which worsens ocean productivity loss--etc.
Yet another reason to try to control CO2 emissions from our machines.