It is only relatively recently that it has dawned upon humans that the ocean is not something that can be taken for granted.
Vast, deep, unfathomable in so many ways, the great body of liquid that envelops our planet at an average depth of some six miles acts as the main regulator of our weather and climate, generator of our atmosphere, and provider, directly and indirectly, of our food and freshwater.
As we begin to grasp how totally dependent we are on the sea for our survival, so do we also understand how much we have harmed it.
"We have learned more about the ocean in the last half century than in all of preceding history," says Sylvia Earle, marine biologist and co-author of National Geographic's new book, "Ocean: An Illustrated Atlas."
But at the same time, more has changed, she told me. "We have lost more than 90 percent of the big fish in the sea and many of the smaller ones too. Half the coral reefs are gone or in serious decline. There are an amazing number of dead zones. That's the bad news.
"The good news: Now we know. It's only when we know that we can care and act to secure for ourselves an enduring place within the natural systems that sustain us."
NGS photo
