Stronger overturning circulation in the Pacific during the last glacial period

Located between Australia and New Zealand, the Tasman Sea is an important but so far neglected component of the global ocean conveyor belt. Now a new study has discovered evidence that this marginal sea in the South Pacific also played an important role in the exchange of water masses between the large ocean basins during the last ice age.

These findings will help to refine climate models and improve our understanding of ocean circulation and carbon storage in the sea, an international team of researchers led by geoscientist Dr Torben Struve from the University of Oldenburg reports in the journal Nature Communications.

In their study the researchers examined 62 fossil specimens of the stony coral Desmophyllum dianthus. These were collected by the underwater remotely operated vehicle JASON during a research expedition south of Tasmania at depths between 1,400 and 1,700 metres. According to dating analysis, these animals lived about 10,000 to 70,000 years ago, a period that included the peak and end of the last glacial period.

“The corals grow in areas with strong currents and turbulence that inhibit the deposition of sediment,” explained Struve, who conducts research in the Marine Isotope Geochemistry group at the University of Oldenburg’s Institute for Chemistry and Biology of the Marine Environment.

Because the skeletons of these sedentary animals record the chemical fingerprint of the surrounding seawater, complex analyses can reveal the chemical composition of the ocean at the corresponding water depth during the corals’ lifetime. This in turn provided clues about which water masses flowed through the Tasman Sea at the time. “These cold-water corals are a particularly good archive for studying the chemical composition of deep ocean currents in the past,” Struve explained.

Young water flowed through the depths of the Tasman Sea
In their study the researchers focused specifically on the ratio of different variants of the trace element neodymium, some of which are produced by radioactive decay and are commonly referred to as radiogenic isotopes. The analysis showed that water from the Pacific Ocean flowed through the depths of the Tasman Sea around the peak of the ice age – as indicated by the relatively high content of radiogenic neodymium in the coral samples.

The investigations also showed that this water from the Pacific had been in contact with the sea surface relatively recently compared to other water masses in the same depth range, or in other words, that it had been relatively “young”.

As the team writes in their paper, the data supports a scenario in which the upper Pacific Ocean was more mixed during the last ice age than it is today – while at the same time the deepest layers were more isolated from the atmosphere, which contributed to the long-term storage of carbon dioxide and the cooler glacial climate.

According to the new study, the circulation patterns during the last glacial period would have looked like this: in the North Pacific, surface water sank to a depth of about 2,000 metres and then spread a long way southward. After flowing around the southern tip of the Australian island of Tasmania, this water could have flowed into the Indian Ocean where it joined the global “conveyor belt” of ocean currents and reinforced it.

This conveyor belt plays an important role in distributing heat among the various ocean basins: the warm North Atlantic Current, for example, is responsible for the comparatively mild climate in northwestern Europe. From the North Atlantic, the circulation extends across the Antarctic Circumpolar Current and the Indian Ocean to the northern Pacific – and then back again. In today’s system, the water in the North Pacific is the oldest, meaning that the last contact with the surface occurred a very long time ago.

The historical view allocated the return flow of this conveyor belt to the Indian Ocean mainly to a relatively shallow strait north of Australia. However, recent studies suggest that the outflow of Pacific waters through the Tasman Sea is also significantly involved in the exchange of water masses between ocean basins – albeit at shallower depths than during the last glacial interval.

It is possible that up to half of the water flowing northwards within the global conveyor belt in the Atlantic today originated in the area south of Australia. “Our study contributes to a better understanding of the dynamics of this global ocean circulation system under changing climatic conditions,” said Struve. Now there is evidence that there was a close link between changes in the deep Tasman outflow and circulation changes in the Pacific Ocean during the last glacial period.

Research Report:A deep Tasman outflow of Pacific waters during the last glacial period

NEWS RELATED

2023 Ford F-150 Lightning Pro MSRP set to increase as supply chain woes continue

Ford is increasing the MSRP of the 2023 Pro trim level of the F-150 Lightning, its all-electric pickup truck, as supply chain challenges have forced the automaker to adjust prices. A Ford spokesperson told Teslarati in an emailed statement today that the company would adjust the MSRP of the ...

View more: 2023 Ford F-150 Lightning Pro MSRP set to increase as supply chain woes continue

How Should the World’s Governments Respond if We Detect an Alien Civilization?

Science fiction is the realm where people traditionally wrestle with the idea of contact with an ETI (Extraterrestrial Intelligence.) But now, those discussions are migrating from science fiction into more serious realms. Academics are going back and forth, one paper at a time, concerning the response and geopolitical fallout ...

View more: How Should the World’s Governments Respond if We Detect an Alien Civilization?

SpaceX's Crew-5 astronaut launch amazing photos

Crew-5 launched toward the International Space Station on Oct. 5.

View more: SpaceX's Crew-5 astronaut launch amazing photos

James Webb Space Telescope and Hubble team up to peer through cosmic dust

The combination of the two telescopes' super powers reveals previously unseen features of a pair of distant galaxies.

View more: James Webb Space Telescope and Hubble team up to peer through cosmic dust

Japan isolated itself from the rest of the world for 265 years. Here’s why.

On September 22, the Prime Minister of Japan, Fumio Kishida, announced the country would be reopening its border for tourists. Starting October 11, you will no longer need a visa to visit the Land of the Rising Sun, nor will you have to join a government-approved, guided tour. Best ...

View more: Japan isolated itself from the rest of the world for 265 years. Here’s why.

SpaceX launches Crew-5 mission to the space station

WASHINGTON — A SpaceX Crew Dragon spacecraft with four people on board is on its way to the International Space Station after a successful launch Oct. 5. A Falcon 9 rocket lifted off from Launch Complex 39A at the Kennedy Space Center at 12 p.m. Eastern after a routine ...

View more: SpaceX launches Crew-5 mission to the space station

Debris From Dimorphos, NASA's Dart Mission Target Left a 10,000 Kilometer Trail [Look]

The Double Asteroid Redirection Test (DART), NASA’s first planetary defense test project, aims to simulate and evaluate a way to defend Earth in the event of an asteroid impact danger. This DART mission successfully changed an asteroid’s orbit by kinetic impact, specifically by slamming a spacecraft into the smaller component ...

View more: Debris From Dimorphos, NASA's Dart Mission Target Left a 10,000 Kilometer Trail [Look]

16 disability ambassadors will take a Zero-G flight for inclusion

AstroAccess is hoping to redesign spaceflight to serve people with disabilities, starting with parabolic flights. Its December opportunity is the second dedicated flight for the organization.

View more: 16 disability ambassadors will take a Zero-G flight for inclusion

The choice we must face when our loved ones die

Startup SpinLaunch aces 10th suborbital launch with high-tech slingshot

A Year After a Failed Launch, Firefly Reaches Orbit and Deploys Satellites

Desalinating seawater sounds easy, but there are cheaper, better ways to get fresh water

What Einstein and Bohr’s debate over quantum entanglement taught us about reality

Adrian Hon

'No Man's Sky' recruits new players with Nintendo Switch expansion, 'relaxed' mode

October's Full Moon Will Peak This Weekend Partially Outshining the Draconid Meteor Shower

Iconic James Webb Space Telescope images get X-ray vision boost

[LOOK] NASA James Webb Images Dazzle in New X-Ray Light from Chandra

Collision may have formed the moon in mere hours

Encalife Ambience Galaxy star projector now 50% off: Save $60

OTHER NEWS

Breaking thailand news, thai news, thailand news Verified News Story Network