A new study warns that climate change could trigger giant tsunamis in the Southern Ocean, triggering underwater landslides in Antarctica. Scientists who drilled cores of sediment hundreds of feet below the seafloor in Antarctica have discovered that during earlier periods of global warming — between 3 million and 15 million years ago — layers of loose sediment formed and slid, sending massive tsunami waves toward the coast of South America. . , New Zealand and Southeast Asia.

Since climate change warming the oceans, researchers believe these tsunamis are likely to occur again. Their findings were published May 18 in the journalism. Nature Communication.

“Underwater landslides are a serious geological hazard that can trigger tsunamis that can cause massive human casualties.” said Jenny GalesLecturer in hydrography and ocean studies at the University of Plymouth, UK. “Our findings highlight the urgent need to improve our understanding of how global climate change may affect the stability of these regions and the potential for future tsunamis.”

For the first time, researchers have found evidence of ancient landslides nearby. Antarctica In the eastern part of the Ross Sea in 2017. Beneath these landslides are layers of soft sediment filled with fossilized sea creatures known as phytoplankton.

Scientists returned to the area in 2018 and dug deep into the seafloor to extract sediment cores – long, thin cylinders of Earth’s crust that reveal layer by layer the geological history of the area.

Analyzing the sediment cores, the scientists learned that layers of light precipitation formed during two periods: one during the mid-Pliocene warm period about 3 million years ago and the other during the Miocene climate optimum about 15 million years ago. During these times, the waters around Antarctica were 5.4 degrees Fahrenheit (3 degrees Celsius) warmer than today, causing outbreaks of algal blooms that, after they died, filled the seafloor with rich and slippery sediment, making the area prone to landslides.

“During subsequent cold climates and ice ages, these slippery strata were covered by thick layers of coarse gravel carried by glaciers and icebergs.” Robert McKay, Director of the Victoria University of Wellington Antarctic Research Center and Co-Chief Scientist of the International Ocean Exploration Program. Expedition 374, which extracted sediment cores in 2018, told Live Science in an email.

The exact cause of underwater landslides that have occurred in the region in the past is not known for certain, but researchers have found the most likely cause: melting glaciers due to climate warming. The end of Earth’s periodic ice ages caused ice sheets to contract and retreat, reducing pressure on Earth’s tectonic plates, causing them to bounce upward in a process known as isostatic rebound.

After sufficient layers of weak sediment had accumulated, continental uplift in Antarctica triggered earthquakes that caused landslides to slide of coarse gravel over slippery layers from the edge of the continental shelf and caused tsunamis.

The scale and size of ancient ocean waves is unknown, but scientists point out two relatively recent underwater landslides that produced massive tsunamis and caused significant human casualties: the 1929 Grand Banks tsunami, which produced waves 13 meters high. and killed about 28 people off the coast of Newfoundland, Canada; and the 1998 Papua New Guinea tsunami, which produced waves of 49 feet (15 m) that claimed the lives of 2,200 people.

While many layers of sediment buried beneath Antarctica and glaciers above the ground are slowly melting, researchers warn that landslides and tsunamis could recur in the future – if true, from melting glaciers in the past.

“The same layers are still present on the outer continental shelf – so it’s ‘ready’ for new landslides to occur, but the question is whether the triggering events are still in place.” said McKay. “We suggested isostatic rebound as a logical potential trigger, but there could be random failure or climate-controlled shifts in ocean currents that act to erode sediment at key locations on the continental shelf that could trigger slope failure. This is something we can use computer models to evaluate for future research.”