creatures on the planet, the so-called unicorn of the ocean with that single tusk that can be up to ten-feet long. they're rumored to live to 90 and dive a mile below the surface. it is the stuff of fantasy. the problem is, the arctic sea ice is melting faster this year than any other on record and it exposes the narwhal to predators making it the most vulnerable species to climate change. the cracks are a stark reminder of realities of global warming. the ice is literally disappearing beneath our feet. >> welcome to the edge of the world, right? >> right. our arctic base camp. >> reporter: our fearless team leader from arctic kingdom polar expeditions. finally we head to the edge where the sea ice meets the open water. one of the richest and most diverse ecosystems on the planet. >> there it is. 6 billion people, one of 20 people here at the flow edge