Under the sea: Atlantis explores ocean’s volcanoes to learn about ice ages
The Daily Astorian
The deck of the research vessel Atlantis bustles with activity, docked Wednesday behind piles of logs at the Port of Astoria waiting for export and dwarfed by the cruise vessel Regatta in port for the day. Its crew of 22 loads refrigerated and storage containers, a small boat, coring cylinders and all the other supplies for its next voyage into the Pacific Ocean.
Meanwhile, a crew of more than 20 scientists from Harvard, Columbia and Oregon State universities, England and China changed lab and research equipment onboard, readying for a 15-day cruise along the Juan De Fuca Ridge off the Oregon and Washington coasts they left for early Thursday morning.
“We’re going out to test the relationship between a glacial cycle and everything that’s happening on the bottom of the ocean, particularly the volcanoes” said Charles Langmuir, a professor of geophysics in Harvard’s Department of Earth and Planetary Sciences, and the chief scientist on the expedition.
Humans, he said, emit about 30 times the carbon dioxide that volcanoes worldwide do. “But we know that the ice ages are controlled by these volcanic emissions.”
Researchers are trying to understand how carbon dioxide coming out of the volcanoes is contributing to the big changes in climate related to ice ages. The hope is that it can provide insight on the effects of carbon dioxide emitted by humans.
Their study is based from the Atlantis, owned by the U.S. Navy and operated by Woods Hole Oceanographic Institute. Research groups funded by the National Science Foundation take turns on the Atlantis, which provides lab spaces, sea-floor mapping sonar and satellite communications. It also is the primary delivery system for the underwater robot Alvin, which is onboard but won’t be used this trip.
To explore the relationship between glacial cycles and hydrothermal activity, the crew aboard the Atlantis is trying to take as many samples from the Earth’s core as possible during its trip. Collecting the actual samples for them is the crew of three from OSU, a national expert at core drilling and sampling along with Woods Hole.
“We’re kind of like the subcontractors, said Chris Moser, a senior faculty research assistant from OSU and a member of its core-sampling team. “If you want to build a house, we come in and do the framing and put the walls up and stuff. We’re subcontracting out as part of their science investigation to get them the mud samples they’re after.”
The Atlantis carries piston corers, long, metal tubes plunged thousands of feet to the ocean floor to collect mud samples. When the cylinders hit bottom and start digging into sediment, a piston in the middle moves up the cylinder and creates suction to help stabilize the sediment filling the cylinder as it sinks. Researchers analyze the sediment on the ship before shipping it back to the East Coast.
A 60-foot sample of sediment, said Langmuir, can help scientists look back through 2 million years. They’ll mostly be looking at the level of hydrothermal activity, cross-checking with historic ice ages to see the relation of the two.
“We think that fat and skinny volcanoes may alternate on the bottom of the sea floor in sync with the change of the ice ages,” said Langmuir, adding that ice ages oscillate every 100,000 years or so, giving scientists maybe 20 ice ages worth of sediment to analyze. “In that case, then also the hydrothermal activity that Alvin is the best tool for studying might change, as the volcanoes get more active and less active.”
While Langmuir focuses on the core samples, Suzanne Carbotte and research scientists from Columbia’s Lamont-Doherty Earth Observatory use a sonar array attached to the Atlantis’ hull to bounce pings off the sea floor and back to the ship.
“We’re going to be mapping the sea floor in very high resolution,” said Carbotte, a member of the Marine Geology and Geophysics department at Columbia.
The general hypotheses researchers are working off, said Carbotte, is that more glacial melting occurs at times of lower sea levels, and vice versa. The hope is that a topographic map will help reflect that variation.
Much of the mapping the observatory collects it often relays for use on Google Earth.
Atlantis for hire
Langmuir’s expedition is the third of about five going out of Astoria on the Atlantis this summer. It often stops at the Port over the summer because of its proximity to the Cascadia Subduction Zone, a convergent plate boundary from northern Vancouver Island in Canada to Northern California where the Juan de Fuca crustal plate subducts beneath the North American plate, which moves slowly in a southwesterly direction.
“This summer we worked on the Endeavor (Ridge) … looking at the wellheads and the vents and monitoring and pulling data strings out of it,” said Chief Mate Mitzi Crane of Woods Hole. The Endeavor Ridge is an active volcanic zone near the north end of the Juan de Fuca plate, off the coasts of Vancouver Island and Washington.
After one or two more trips from Astoria, the Atlantis follows the fair weather south to San Francisco for similar research, then on to Costa Rica and finally Chile.
“We’re fair-weather sailors,” said Capt. Al Lunt, who recently switched on as head of the vessel for a six-month tour. “We like it that way.”
‘We know that the ice ages are controlled by these volcanic emissions.’
— Charles Langmuir
professor of geophysics and the chief scientist on the expedition.