Hidden Mountain Range Discovered in World's Strongest Ocean Current

An ancient, hidden mountain range has been discovered above a hotspot lying amongst the strongest ocean current on Earth.

The discovery was made by researchers on board a voyage in the Southern Ocean, by Australian government agency the Commonwealth Scientific and Industrial Research Organisation (ISIRO). The findings have been detailed in a study that has not yet been peer reviewed.

The researchers onboard the Investigator research vessel were originally working to study the Antarctic circumpolar current—the strongest current in the world's oceans—to better understand how it contributes to rising sea levels. In particular, they were looking at how the current is leaking heat towards the continent.

While doing so, they scanned a previously unmapped area of ocean, which spans 200 nautical miles west of Macquarie Island.

Below the strong, swirling currents, lying around 13,100 feet below the surface between Tasmania and Antarctica, was an underwater mountain range.

This "spectacular chain of ancient seamounts" included eight dormant underwater volcanoes that had peaks of heights of nearly 5,000 feet, SIRO geophysicist Chris Yule said in a press release detailing the findings. One of them even had a double vent.

"Four of them are new discoveries, and we filled in details on two seamounts and a fault line ridge partially mapped on a previous voyage. We now know the ridge, just west of the survey area, drops into a valley over a 1,600 mature high cliff [5,249 feet]," Yule said.

This area is based near the tectonically active Macquarie Ridge. The mountains likely formed 20 million years ago from the hotspot lying below the Earth's mantle.

Discoveries such as this are vital for the understanding of ocean dynamics, according to the co-chief scientist on board the voyage, Helen Phillips, who works on the Australian Antarctic Program Partnership at the University of Tasmania.

"The Antarctic Circumpolar Current 'feels' the seafloor and the mountains in its path, and where it encounters barriers like ridges or seamounts, 'wiggles' are created in the water flow that form eddies. Valleys and cliffs can also accelerate deep currents at the bottom of the ocean," Phillips said in a press release. "Eddies are like the weather systems of the ocean, playing a major role in transporting heat and carbon from the upper ocean to deeper layers—a critical buffer against global warming. Knowledge of the depth and shape of the sea floor is crucial for us to quantify the influence of undersea mountains, hills and valleys on the Antarctic Circumpolar Current and the leaking of heat towards Antarctica."

The voyage used a new satellite developed by NASA and French space agency, the National Centre for Space Studies. This allowed the researchers to scan high resolution images of the seafloor.

The Antarctic Circumpolar Current flows clockwise, from west to east around the continent. It is not only the strongest current in the world but it is the only one that links all of the world's oceans. Therefore, it is a particularly important current to study for scientists to understand what is happening to the world's oceans due to climate change.

"The ocean has absorbed more than 90 percent of heat due to global warming and around 25 percent of human CO2 emissions, providing an enormous service as a climate shock absorber," Benoit Legresy, chief scientist on board the voyage, said in the press release. "Knowing how to deal with human-induced climate change brings an urgency to tracking down the heat and cartoon pathways in the global climate system. We've been working in a gateway where heat is funneled towards Antarctica, contributing to ice melt and sea level rise. We need to understand how this gate worlds, how much heat gets through and how this may change in the future."

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