A rise in sea levels isn’t the only impact global warming is having on the world’s oceans. A growing body of evidence suggests that climate change is also affecting ocean currents and the chemistry of the seas, with potentially catastrophic results.

This week, PBS’ NOW travels deep into the oceans with scientists from the Woods Hole Oceanographic Institution (WHOI) with help from other researchers for a first hand look at this stunning sea change, and what we can do about it.