Between 1969 and 1972, 12 people (all of them men) walked on the moon, took an afternoon stroll 240,000 miles away. Around this same time, Sylvia Earle, the first chief scientist for the National Oceanographic and Atmospheric Administration, was just learning to dive deep below the surface of the sea. Back then the tempertature of the earth was about one degree cooler than it is today, coral reefs were thriving, and we still thought of the ocean as “too big to fail,” Earle said in a lecture on Wednesday evening to kick off the first annual Sustaining Coastal Cities conference, an event hosted by the College of Science.

A “living legend” according to the Library of Congress, Earle first became enamored with the sea as a kid when she read a book by William Beebe, the man who developed the first underwater breathing system, which he and Otis Barton used to plunge themselves a half mile down. Beebe’s observations showed Earle that the ocean was more than just a big puddle of water, it was alive. It contained sea horses, whales, dolphins, and stomatopods. Ninety percent of its creatures, she said, communicate with one another through intricate bioluminescent patterns. These creatures, and their quiet impact on the rest of the planet, fascinated her.

Today, nearly half a century after Earle learned to dive, we are beginning to set our sights on Mars. And yet we still aren’t capable of going much deeper into the ocean than Beebe and Barton did in the 1930s. “We’ve spent billions to access the skies above,” said Earle, “and it has paid off enormously. But we’ve neglected the oceans and it’s costing us deeply.”

The ocean is an enormous sink for carbon dioxide and the phytoplankton that populate its upper layers generate as much as 70 percent of the earth’s oxygen. “If you like to breathe,” said Earle, “you’ll take care of the plankton.” But the plankton don’t stand alone, they are but one organism in a vast system of organisms and processes that rely on one another for optimal survival. Too much phytoplankton, and the coral reefs begin to suffer. When the corals suffer, the fish that eat them do, too. When the fish suffer, humans suffer. We rely on marine organisms for a huge portion of our protein supply, and thousands of fishing communities across the globe rely on them for their very survival.

The ocean governs the weather, the climate, and dozens of natural cycles like the carbon cycle and the water cycle. So, if we don’t take care of the ocean, Earle said, we’ll ultimately destroy ourselves. But we haven’t been taking care of them. We’ve actually been treating them pretty badly over the last century or so. Back in the day, Earle said, the ocean was so unknown to us we imagined it to be a great sink, capable of absorbing all of our waste. We’ve since learned better, but the plastics and other refuse that have made–and continue to make–their way into the sea over the years spell turmoil for marine life.

The coral reefs that were thriving when Earle learned to dive have since suffered greatly. Half of them have been destroyed due to bleaching, a result of increased ocean acidification, itself a result of climate change. The temperature of the earth is now higher than it has ever been in Earth’s history, and lies well outside the range of normal temperature fluctuations. Carbon dioxide levels in the atmosphere are rising sharply, and we’re beginning to worry about our ability to survive on this planet in the long term. As we try to figure out ways to make Mars, with its high CO2 levels limited or non-existant water supply, a more habitable place, Earle said, we continue “Marsifying Earth.”

“We have to make peace with the blue planet before we can ever responsibly go to another one,” she said.

The good news, though, is that “now we know,” now we’re asking the right questions, now we can look at the past, see its impact on the present, and project into the future with that knowledge. “We are living in the most extraordinary time in human history,” Earle said. We’re at a sweet spot where we can either keep staying this destructive course, or we can wake up, pay attention, and make some changes. While half the corals are gone, Earle reminded the audience on Wednesday, half of them are still alive.

Earle has spent months of her life living on the bottom of the ocean. She led the first team of women “aquanauts” down there in the 1970’s and has had the opportunity to go back ten separate times. She’s 77 years old but she has no plans for settling down up top any time soon. She is one of the 0.1 percent of humanity that’s seen the deep ocean and all that it holds. There are creatures down there that are seven thousand years old. “Imagine what humanity was doing seven thousand years ago,” she said. But since it’s all buried so deep below the horizon we’re used to, few of us realize the great jungle it contains. The deeper you go, Earle said, the less we know about the creatures and the less we know how our behaviors on land are impacting them. If we ever hope to truly understand climate change and its impact on the environment, we have to spend just as much time and money exploring the depths of our own planet as we have exploring those beyond, Earle said. As we continue to move onward and upward, we should also consider going downward. I never realized it before, but I’m in complete agreement.

And just in case you missed it, or haven’t enough Sylvia Earle, here’s Wednesday night’s talk in full, courtesy of the College of Science:

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