We traversed the threshold between the Atlantic and the Arctic Oceans. The south-bound East Greenland current squeezed between the craggy coasts of Iceland and Greenland to become a "superhighway" for turbulent water. Here, the denser Arctic water mass crashes into the bulwark front of warmer Atlantic Water. Arctic water plunges downwards into the Denmark Strait Cataract. This is the world's largest waterfall. Yet, skimming the surface of immense water all we see are waves that crest white tumble and stream like the tossed manes of charging horses.
Unfortunately, we also saw the threats to nature.
First, a quick science lesson: When seawater freezes at the ocean surface, the ice is actually made of freshwater; the salt gets rejected back into the surrounding water. That surrounding water then becomes denser and sinks. This happens on a massive scale, which results in ocean currents around the world. Think of it like an organic engine that circulates the oceans' water.
Now, because global warming exposes more of the surface every summer than it used to (about twice as much, in fact) that means more surface ice each winter. That means that our ocean circulation engine is twice as big, which radically alters the seascape, threatens not only the ocean ecosystem – from tiny algae to those humpback whales – but life worldwide.