Scientists have created the most accurate map to date of the mountains, canyons, and plains that make up the floor of the Southern Ocean surrounding Antarctica.
Covering 48 million sq km (18.5 million sq mi), this chart reveals for the first time a new deepest point: the Factorian Deep, a 7,432-meter-deep depression.
Understanding the structure of the ocean floor is crucial for safe navigation, marine conservation, and comprehending the climate and geological history of the Earth.
However, we have much to learn.
Huge areas of land have never been accurately mapped.
It took five years to produce the International Bathymetric Chart of the Southern Ocean (IBCSO), which updates the first attempt at a complete map, which was published in 2013.
The IBCSO and similar projects around the world are increasingly filling up the gaps in our limited understanding of the ocean floor.
Governments, organizations, and institutions are urged not to hide data and to put as much as possible in the public domain. Ships and boats are also encouraged to routinely turn on their sonar instruments to obtain bathymetric measurements. This is currently profitable.
The new map depicts the whole floor of the Southern Ocean south of 50 degrees South. If its 48 million square kilometers are divided into 500m grid squares, 23% of these cells have at least one current depth measurement.
This is a significant improvement from nine years ago.
IBCSO began at 60 degrees South at the time, and less than 17 percent of its grid boxes contained contemporary measurements.
Dr. Boris Dorschel of Germany’s Alfred Wegener Institute stated, “You must comprehend the significance of the change from 60 degrees to 50 degrees; we’ve more than doubled the chart’s area.”
“Therefore, we have enhanced both the geographical coverage and the data density, as we have continued to acquire new data and knock on doors to free up current data,”
The majority of the material in the graphic originates from ice-strengthened ships that support scientific endeavors in Antarctica, including the RRS James Clark Ross, the United Kingdom’s former polar ship. (In the future, this British contribution will be made by its successor, the affectionately-named RRS Sir David Attenborough)
As these vessels travel between the White Continent and locations such as Chile, South Africa, and Tasmania, their echo sounders routinely scan the submerged topography.
And this activity is more coordinated, with research organizations from several nations collaborating to slightly offset their icebreakers’ paths.
The RRS Sir David Attenborough, the United Kingdom’s new polar vessel, is designed to map millions of square kilometers of ocean floor throughout its career. The image seen above depicts the ship’s hull in a dry dock. The yellow rectangle in the middle is a synthetic material cover for the 8-meter-long array of transmitting transducers for the multibeam echo-sounding system in deep water.
There are numerous reasons why more accurate seafloor maps are required.
They are crucial not just for safe navigation, but also for fisheries management and conservation, as marine life prefers to gather around underwater mountains. Each seamount is a hotspot for biodiversity.
In addition, the rocky bottom affects the behavior of ocean currents and vertical water mixing. This knowledge is necessary to improve the models used to predict future climate change, as oceans play a crucial role in the global distribution of heat.
The British Antarctic Survey’s Dr. Rob Larter elaborated, “By observing the seafloor, we can also examine how the Antarctic Ice Sheet has altered over thousands of years.”
“There is a record of where the ice flowed and the extent of its grounded zones (places in contact with the seafloor). This is exquisitely preserved in the form of a seabed.”
The new map was made possible by funding from Japan’s Nippon Foundation and assistance from Seabed2030, an international initiative to accurately map the ocean floor by the end of this decade.
Our current understanding of four-fifths of the planet’s underwater landscape is based only on low-resolution satellite data that infer the existence of high seamounts and deep valleys based on the gravitational influence these structures have on the sea surface. Over the mass of a massive underwater mountain, water accumulates and there is a slight dip where there is a trench.
In the years between the first and second editions of IBCSO, the deepest point of the Southern Ocean was identified. At the southern end of the South Sandwich Trench is a depression named Factorian Deep. It is 7,432 meters deep. In 2019, it was measured and explored by the Texan explorer Victor Vescovo aboard his submarine Limiting Factor.
Due to the remote and frequently inhospitable condition of the Southern Ocean, it seems doubtful that large portions of it will be mapped without committed effort. There is optimism that an emerging class of robotic vessels may be assigned this mission in the coming years.
