around that time, scientists learned something extraordinary. whales were communicating with each other. sometimes by song over long distances. in part, because of that discovery, scientists and conservationists rallied to enact laws to protect the whales and it worked. the humpback whale population has made a remarkable comeback. now they face a host of new threats. global warming is killing off their food source and human activity is causing thousands of whale deaths a year from the stress of underwater construction noise to fishing entang amments and ship collisions. in the next hour, cnn s bill weir takes us to antarctica, a place very few get to visit to study these remarkable creatures and show us why saving the whales may also be saving the planet. because they are one of our best partners in battling climate change. reporter: those are the songs of humpback whales, flying about 15 billion miles away from earth, on the off chance intelligent life out there wants to