Antarctic isolation and the global climate

Figure 1. The Drake Passage in the Southern Ocean, part of the Antarctic Circumpolar Current path, opened approximately 37 mya . 

The opening of the Drake Passage about 37 million years ago was a great stage in the development of the state of the modern world as we experience it today. Previously all the world oceans were not connected as Gondwana was breaking apart still over 40-60 mya. The global climate was warmer and the atmospheric and oceanic teleconnections were very different to what they are today.

As the Antarctic Circumpolar Current became whole, through the opening of Drake Passage, all the world's oceans became connected to the single continuous Southern Ocean around Antarctica. This completely altered the state of teleconnections between the oceanic and atmospheric spheres of the earth. As the isolation of the Antarctic continent resulted in a drop in global temperature over a long period of time through formation of gigantic ice sheets and sequestered carbon dioxide. Antarctic bottom water (AABW) began to drive an oceanic conveyor belt worldwide, driving mass currents of water to and from the north and south poles. 

This massive global change would have altered the behaviour and limitations of many animals. It is likely that many animals today, that have complex migratory behaviours, developed these after the isolation of Antarctica. Many flying marine birds migrate to the Sub-Antarctic and Antarctic islands to breed and feed, and many birds utilise the atmospheric streams to assist them in long-haul journeys.