An example of how a broken link in a food chain can wipe the whole chain out.
Their main diet , small fish, and squid, in turn rely on krill-tiny shrimp- which are sensitive to temperature change. Many Whale species prime source of food is also krill. There are many other creatures whose sensitivity to temperature can make life for them literally impossible either through being unable to survive themselves or through a threat to their food sources and so food chains. The environment is a house of cards, being dismantled from the bottom up. When the house collapses, it will do so in a flash. We won't have time to get our coats.

Fisheries are breeding barramundi in Tasmania - just shows how water temperatures have risen. This would have been virtually impossible 10 years ago.