By Paul Beckwith
About 5 million years ago continental drift pushed North and South America together, creating the Isthmus of Panama where the Central American Seaway ocean passage had previously existed. The Pacific and Atlantic were no longer connected, drastically altering global ocean currents and atmospheric circulation patterns. As the Atlantic Gulf Stream strengthened, it carried vast amounts of moisture into the northern regions. The Arctic eventually cooled and it’s estimated sea ice cover has existed continuously in the Arctic Ocean for 3 million years, possibly for as long as 13 million years.