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Measuring climate change, on the backs of scuba divers

Pierre-Yves Cousteau, son of famed oceanographer Jacques Cousteau, is looking for data in places ships and buoys can’t reach

By Stav Dimitropoulos

Earlier this century, some marine biologists, realizing their knowledge of ocean conditions in the most remote parts of the planet was limited, enlisted an unwitting set of partners: Antarctic seals.

It was 2004, and the scientists — through a consortium they called Marine Mammals Exploring the Oceans Pole to Pole — began outfitting seals in the Antarctic with sophisticated sensors, attached to their heads, that fall off harmlessly when the animals molt. When the seals dive, the headgear measures the properties of the water. When the seals resurface, the headgear transmits data back by satellite. The high-tech seals, which now include species in the North Pacific and North Atlantic, have since collected nearly 400,000 profiles of the ocean environment, recording everything from temperatures to salt content — helping humankind amass intricate information about some of the world’s iciest and most remote waters.

But working with seals means working only in the parts of the world’s oceans that they frequent. So a new project starting this February will monitor climate change in action in warmer waters — not on the heads of seals, but on the air tanks of human divers. The new effort, called Project Hermes, is spearheaded by Pierre-Yves Cousteau, a marine conservationist and son of the biblical figure of oceanography, Jacques-Yves Cousteau.

“There is a lack of data about shallow coastal ocean temperatures,” Cousteau says. “Divers can help fill the void.”

Pierre-Yves Cousteau, a marine conservationist and son of Jacques-Yves Cousteau, heads Project Hermes. Photo by Philippe Dannic/Sipa via AP

In some respects, Cousteau’s ambitious project is a way of leaving his own mark on the world. His famous father started taking him to scuba diving lessons when he was 9. Now 37, the younger Cousteau became an expert diving instructor 10 years ago, creating Cousteau Divers, a worldwide community of divers and dive centers with a mission of protecting marine life.

“It’s important to define yourself as a person regardless of where you come from,” he says. “I learned to dive and became an instructor not because my name is Cousteau, but because I have a passion for the ocean and for sharing that passion.” Though he prefers to define himself on his own terms, he agrees that his surname carries his father’s “very positive values of exploration, stewardship, and innovation.”

The project’s concept is fairly simple. Divers wear a so-called Remora device, a portable precision temperature sensor — a plastic cylinder about the size of a water bottle. Named after a slender fish that often attaches itself to sharks, and developed by volunteer engineers Brad Bazemore and Brendan Walters, the Remora measures water temperature with high accuracy and uses GPS to record underwater navigational information. As soon as it comes within WiFi range, the Remora autonomously sends the data to the Project Hermes website.

“The project is a great opportunity for us to leverage citizen science and empower ocean lovers to help better understand the ocean.”

Together, the divers will contribute to a prolonged monitoring of the oceans’ vital signs.

“There is a gap in our understanding of ocean thermodynamics,” says Cousteau. “The project is a great opportunity for us to leverage citizen science and empower ocean lovers to help better understand the ocean.” All generated data will be publicly available, and Cousteau Divers intends to contribute it to scientific databases. Cousteau Divers has made the Remora software available via an open-source license.

“Cousteau’s new project is a huge but feasible undertaking,” says Michael J. Budziszek, an expert on global warming and associate professor at Johnson and Wales University in Providence, Rhode Island. Currently, he says, sea surface temperature is measured by satellites, which can’t penetrate far below the ocean’s surface; and buoys, moorings, oceanic vessels, and shoreline instruments, which can only cover limited areas and depths. Divers, Budziszek says, “will provide a better picture of ocean temperature fluctuations from the surface to various depths.”

By doing so, Project Hermes aims to improve the public’s understanding of the ocean and the threat of climate change, in hopes of compelling action. Since the 1970s, the world’s oceans have absorbed more than 90 percent of the heat from human-caused global warming, by one estimate. Had the oceans not trapped all this heat, global temperatures would have escalated by an estimated 97 degrees Fahrenheit. But climate change is affecting the oceans, as well: fish are dying, polar ice is melting, and altered currents are disturbing the migratory patterns of many marine mammals and fish.

Cousteau conceived of Project Hermes several years ago, but it took him years to raise enough funding for it. In the summer of 2019, Swiss luxury watch manufacturer IWC Schaffhausen announced it would sponsor the project. Now Cousteau is ready to launch the first 50 sensors in scuba diving centers around the world, from Greece to Hawaii. He says he hopes the number of divers wearing the Remoras will soon snowball. Experts agree. “I can easily imagine that, if the project catches on, you could have several hundred divers, and then you could be getting a lot of data from a lot of different parts of the ocean,” says sea ice scientist Peter Wadhams, a retired University of Cambridge professor.

One of the first divers to kickstart Project Hermes is Apostolos Stylianopoulos, 45. A master diving instructor and member of Cousteau Divers, he has spent 15 years descending through the volcanic waters of Santorini, Greece — and was motivated by what he’s seen to add the Project Hermes device to his air tank.

In the Mediterranean Sea, where Stylianopoulos has logged 6,500 dives, 41 percent of all marine mammals and 34 percent of the total fish population have perished over the past 50 years, due to overfishing, pollution, and climate change. Lately, he has noticed a quirky phenomenon: tropical fish such as puffers and lion fish, which the temperate Mediterranean has never seen before, are now swimming in schools around Santorini. “They eat the native fish,” he says. “At the rate we are going, we may not have enough fish in the years to come.”

Crises of the environment, climate, economy, and moral sphere are not new. They go hand in hand with the history of humankind, something Cousteau’s legendary father had pinpointed well in his lifetime. In a January 1996 editorial for the Calypso Log, the Cousteau Society’s member magazine, the elder Cousteau wrote: “It is the duty of the youth, in a world that will soon count 10 billion individuals, to demand a better sharing of the planet’s resources, to abolish waste and misery, and to replace the dictatorships of technocrats and of the market economy with concentration, justice, and innovation.”

Today, his son believes, this duty may lie with divers.

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Stav Dimitropoulos is a writer based in Athens, Berlin, and New York.

Illustrator Leonard Dupond

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