The Underwater Continent of Zealandia Could Predict Earth's Future

When you’re 600 miles away from land, hunting for a lost continent aboard a ship in the Tasman Sea between Australia and New Zealand, the blue-black waves won’t offer any clues. Days on the JOIDES Resolution are spent eating Filipino food, waiting for the next day’s experiments, and analyzing fossils unearthed from the seabed.

For Gerald Dickens, Ph.D., the co-chief scientist on the recent expedition to Zealandia — the submerged hunk of continental crust that sank after breaking off Australia — the journey, and its aftermath, has been a mix of wild, often inexplicable emotions.

“There is the true thrill of the findings, both expected and unexpected,” Dickens, who’s also a professor at Rice University, tells Inverse. “This is then blended with the personal issues of being on a ship, working more than 14 hours a day with the same people, day in and day out for two months, all away from any sense of normalcy and most connections to family.”

“I chase science on the ocean”

Dickens, though, is acutely aware of how tremendously rad his job can be: “This is my life: I chase science on the ocean,” he says. “It’s really hard to pick a favorite part, because I cannot complain about being paid a decent salary for hanging out with smart and cool people exploring.”

For two months, Dickens, along with 30 other researchers and 20 crew members, probed the 5 million square kilometers that belong to what’s considered the world’s eighth continent. Some 94 percent of Zealandia is underwater — its visible crust previously thought to be scattered islands of New Zealand and New Caledonia. It wasn’t until 1995 that scientists became vocal about how it could be a continent, and it was just back in February when scientists announced they had enough geophysical data to confidently say the stretch of separated crust deserved the title.

When the team set out in July aboard the JOIDES Resolution — a massive research vessel equipped with a drill pipe that can retrieve thousands of feet of sediment — they became the first crew to expressly go to an unexplored continent and bring back evidence of what its existence means for the geological record and our future on Earth.

The JOIDES Resolution

“If you’re trying to predict what is going to happen in the future, it’s important to understand what has happened in the past,” explains Jamie Allan, Ph.D., a program director for the National Science Foundation’s Division of Ocean Sciences. “That’s the value of these cores — if we’re trying to model how fast the climate is going to change, we can look at the past.”

The cores Allan is referring to are the 8,202 feet of sediment cores collected at six Zealandia sites, drilled samples containing layers of Earth that could reveal how the geography, volcanism, and climate on the continent changed in the last 70 million years.

At six sites, the scientists drilled 4,101 feet down into the seabed, ultimately collecting the 8,202 feet of sediment cores. To drill, core barrels are lowered into the drill pipe and a huge amount of pressure via compressed water is applied, which allows the barrel to collect 9.5 meters of core every 90 minutes. The inner core barrel, about the width of a paper towel roll, which contains the core, is then pulled back into the ship.

Drilling cores are the modus operandi for the JOIDES Resolution. As one of the world’s most advanced scientific drill ships, it’s part of a fleet used by the International Ocean Discovery Program, a global marine research program whose expeditions are staffed by scientists from 23 countries.

“Big geographic changes across northern Zealandia, which is about the same size as India, have implications for understanding questions such as how plants and animals dispersed and evolved in the South Pacific,” says co-chief scientist Rupert Sutherland of Victoria University of Wellington in New Zealand. “The discovery of past land and shallow seas now provides an explanation. There were pathways for animals and plants to move along.”

The data collected, however, is open access to all scientists hoping to study the samples, and the cores collected are later housed within repositories in Germany, Japan, and the United States.

“One thing that’s really important about this, is that the science is bottom-up,” explains Allan. “There’s completely unfettered capability to publish the data.” (Allan explains that the discovering party has a moratorium period of a little more than a year, where only they have access to the data, but after that, anybody can study sediment samples from the sunken continent.)

Ball’s Pyramid, part of the submerged continent of Zealandia.

The dug-up soil samples will first go to the repository and lab at Texas A&M University, where scientists will analyze their chemical composition, before being shipped to the Kochi Core Center in Japan.

“This core repository is remarkable,” marvels Allan. “It’s on-site at Kochi University, and it’s in a tsunami-proof building. It’s like walking into a bank vault.”

Scientists hope to determine from the cores, and the several hundred fossil specimens contained within them, a detailed record of Zealandia’s past and hints on how the Earth’s climate has evolved over millions of years.

Dickens, who became involved with the International Ocean Discovery Program 22 years ago as a graduate student after a stint as a card dealer in Nevada, says the plan is to “test basic models of how Earth works in time and space, which impinges on root questions to more mundane things like earthquakes and climate change.”

Mundane here is relative: Portions of Zealandia have been underwater or slightly visible for thousands of years. About 85 million years ago, it split from the massive continent that also consisted of Antarctica and Australia.

“The best way to visualize it is to say 35 million years ago, there were crocodiles living on Antarctica,” Allan says.

A massive plate movement called “seafloor spreading” created the Tasman Sea, lifted New Zealand above the waterline, and developed a new arc of volcanoes. Analyzing Zealandia’s cores will hopefully demonstrate how plate subduction begins, and the timing and cause of this change.

What Zealandia might’ve looked like: the Humboldt Mountains on the South Island of New Zealand

The cores also have the potential to reveal changes that have happened in the Earth’s ocean circulation and climate, and its inclusion into climate models can help scientists create more accurate models of ancient climates. Between 16 to 45 million years ago, levels of carbon dioxide were as high as the levels predicted we’ll reach by the end of the century. Sediments, microfossils, and geochemical data collected for cores can reveal what life was like during these years of high CO2 conditions — and indicates to scientists what we should be prepared to experience.

“If we’re trying to model how fast the climate is going to change, we can look to these cores and ice cores,” says Allan. “It appears that we’re going back to the conditions of the Pleistocene [before the ice ages] where there was about the same level of CO2 in the atmosphere as there is now. That’s intriguing to me because it seems like we’re eventually going to be at the exact same level — the question is how fast. Is it going to take thousands of years, hundreds, or decades?”

Dickens says it will take a few years before the first findings can be presented, and predicts that there will be at least two drilling expeditions returning to Zealandia over the next 10 years if there’s support for it. What’s been found is scientifically exciting, but the exact importance remains to be revealed. There are likely more clues about the planet’s past waiting to be collected.

“I think also that we did not fully recover what we could have, now that we understand the records much better,” Dickens says.