Wearing a hard hat and safety glasses, Brown University graduate student Bryce Mitsunaga pulls nitrile gloves onto his hands, picks up a plastic bin of tools and positions himself at the end of a series of metal workstations.
Moments later, a team of technicians carries a 30-foot-long plastic tube full of mud and sets it in a rack that runs the length of the catwalk where Mitsunaga bounces a bit with anticipation. He quickly takes a small plug of mud, which was just pulled up from deep beneath the seafloor. He’ll bring it to the chemistry lab for analysis, “partially for research interests,” he says, “and then partially to make sure that we don’t blow ourselves up as we’re drilling.”
Mitsunaga and one of his advisors, Brown professor Tim Herbert, are at sea onboard the JOIDES Resolution, part of a team that wants to learn more about the past and help us plan for, and possibly avert, the worst impacts of climate change.
“The ship is an incredible, sophisticated time machine that takes us back,” Herbert says. “One of the great things about exploring the deep sea is, literally, there’s no information for hundreds or maybe thousands of miles of the kind that we’re going to get on this cruise.”
The JOIDES Resolution, originally built in the 1970s for oil exploration and converted to scientific research in the mid-1980s, is bigger than any fishing boat but smaller than a luxury cruise ship. Picture a West Texas oil derrick sitting on the deck of a small container ship. It’s equipped with miles of heavy pipe that can be put through the boat and positioned on the seafloor. Then, the drilling team sends long plastic tubes through that column and into the mud below the water. The sediment, extracted in the PVC tubes, becomes the basis for interdisciplinary studies of Earth’s history.
There are 117 people onboard, including the scientists and technicians, the ship and drilling crews and the hospitality team. The boat sails almost continuously, changing crews every two months, and has drilled in all the world’s oceans.
This time, the cores that come up from as much as 600 yards below the seafloor will give the scientists pieces of a puzzle that will help them understand what the global climate was like millions of years ago.
“We’re traveling back in time to a period when there was no Greenland ice cap, the climate was a lot warmer,” Herbert says, “to try to learn about how warm climates work.”
Mitsunaga and Herbert were selected by the two co-chief scientists who spent 13 years putting together the plans to drill at four specific locations in an area just off the coast of Portugal known as the Iberian margin, where the water depth ranges from less than 1,500 meters (4,900 feet) at the shallowest site to more than 4,500 meters (14,800 feet, or 2.8 miles) at the deepest one. In addition to these varying depths, the proximity to land and the way ocean water moves through this region all make this area unique.
Back in 2000, a British scientist who helped found the discipline of paleoceanography – the study of the ocean’s past – Nicholas Shackleton, demonstrated that climate records derived from the sediment samples taken in this area correlated perfectly with records created from ice samples drilled both in Greenland and Antarctica.
That means what scientists learn here can help us understand more about what that warmer climate was like not just right around Europe but also near the north and south poles.
“It’s kind of mind blowing a bit – one place in the ocean, one sediment core, can have links and components to both of the poles as well as the European continent,” says University of Cambridge professor David Hodell, one of the expedition’s co-chief scientists. “But that’s what makes this Iberian margin so special and there’s really no place else in the world’s ocean that I can think of that has these sort of attributes.” (Hodell and the other co-chief, Fátima Abrantes of the Portuguese Institute for the Sea and Atmosphere, both earned their doctorates at the University of Rhode Island’s Graduate School of Oceanography.)
The co-chiefs wanted to extend Shackleton’s work by drilling much deeper, extending the global climate record back to perhaps 5 million years ago. Every time Mitsunaga meets another core sample as it comes onto the ship’s deck, he’s helping collect more pieces of the climate puzzle.
After he takes his tools and plug of mud inside, technicians measure and cut the core into 3- to 4-foot sections. In the adjacent lab, after the technicians split the sections lengthwise, the scientists finally get to see what they’ve come for.
“They’re bright and they’re full of color and they’re full of ancient worm burrows and all kinds of things that were living here thousands and millions of years ago,” Herbert says.
The sediment contains microfossils, minerals, pollen, sometimes even coral, all of which help the scientists figure out the age of a core. Other studies, on the ship and in their labs back home, will determine details such as the ocean temperature and salinity at that time, the air conditions including atmospheric carbon dioxide, and some details about the climate on nearby land.
As cores move through the ship’s labs, researchers input data into a database accessible to the whole science team. It’s Herbert’s job to aggregate that data. At each site, the drillers pull up mud from multiple holes. As a stratigraphic correlator, Herbert lines up the data from each hole side by side. His goal is to determine what age corresponds with what depth. His computer monitor shows several columns each with a different colored wiggly line running top to bottom, with visible peaks that should match from one column to the next. Herbert sees in the data the cycles of Earth’s warming and cooling.
“These wiggles that we see are essentially the heartbeat of earth’s climate, written in the sediments,” he says.
The sediment has meticulously recorded these changes but the scientists have to tease out specific details they’re looking for. Mitsunaga, for example, wants to better understand what the land, air and ocean conditions were back when what we think of as the characteristic Mediterranean climate was emerging.
“We’re still not entirely sure why, or what was going on around the trees and plants as that was happening,” he says.
They do know it happened about 3 to 3-and-a-half million years ago. This expedition’s plans suggested the mud recovered would likely be 3 to 5 million years old, so he figured he’d find what he was looking for. But the first site far exceeded his expectations.
“We got to 15 million (years ago) there. And that was … a surprise to everyone,” he says. “Even the people organizing this, the chief scientists — they were blown away. Now we have three times as much of earth’s history to work with.”
Herbert and colleagues in Rhode Island have used similar techniques to document more recent climate history. Sediment cores from Narragansett Bay helped them recreate the Rhode Island coastline from centuries past. Herbert says the historically steady change in sea level abruptly increased around the start of the Industrial Revolution, when metals began polluting the water.
“They were being put in by the early craftsmen and factories of Providence, so we know when human beings affected things because a lot of the sediment has the fingerprint of industrial activity, human activity, and we see that right in our backyard,” he says.
Combining relatively recent history with the geologic past is how scientists determined that people have altered natural sea level changes.
“We know for sure that the current rate of sea level rise is completely unusual for the last thousands of years,” Herbert says.
Now, with mud that contains signals from around the globe taking them back millions of years, these scientists from a dozen countries will add to the understanding of what might be coming.
“One of our goals in the long run is to reconstruct more precisely the kind of temperatures that went along with that,” Herbert says, “to sort of help with maybe what we could call a ‘speed limit’ that we need to set for global warming to prevent major things like sea level rise that would affect the Rhode Island coast in a really big way.”
Flat coastal areas, like much of Rhode Island and southeast Massachusetts, will be particularly vulnerable to sea level rise. Paleoclimate data – details of Earth’s past climates – can help improve the models that will predict what’s coming.
Working on a ship for two months has its challenges. Carbon, that pesky element we hear so much about in conversations about climate change, is something the scientists want to measure in the sediment. To do that, Mitsunaga grinds some of the sediment into a fine powder. Before he can do the experiments that generate the carbon data, though, he needs to weigh the little bit of that powder he scoops onto a thin paper. Weighing tiny amounts is a big deal in a floating lab, so his scale takes multiple measurements.
“It calculates your average center of gravity and mass over several minutes,” he says, “instead of just doing it instantaneously – which is fine if you’re on dry land but not if you’re in the middle of a wave.”
Showering is another thing he says is a little more difficult on a ship. It’s also not easy to leave friends and family — including pets — for more than two months. Internet connections help. But it’s something most scientists will do only once or possibly a couple of times in their careers.
For Mitsunaga it’s a welcome adventure.
“The bottom of the ocean is probably the closest we can get to looking at another planet without going to a different planet,” Mitsunaga says. “I think everyone thinks that’s cool.”
And being at sea is also liberating, he says, because most day-to-day responsibilities disappear. It’s just all science for 12-hour shifts, seven days a week.
“If you love what you do, and if you like the science that you do, then I think this is kind of like a dream,” Mitsunaga says.
With nightmarish climate predictions, Herbert says this work could calm some nerves by providing information from a warmer world.
“We’re going to come back with kilometers of mud, many millions of years, to try to investigate,” he says. “I imagine we’re going to keep a lot of Brown undergraduates and graduate students busy for a number of years to come.”
Reporter Amy Mayer is sailing onboard Expedition 397 as an outreach officer. Follow her on Twitter @AmyHMayer
