Fish teeth rewrite the history of the great ocean current around Antarctica

The Earth is a complex system in which all “spheres” interact: atmosphere, hydrosphere and geosphere. Understanding the evolution of the planet and the major changes that have occurred, or are occurring, can only be done by considering all the components of this system. Climate evolution, in particular, cannot be separated from ocean currents and major geological processes such as plate tectonics. The currents that move the world's oceans help regulate temperatures, as well as humidity. They participate in the carbon cycle and ensure dispersion NutrientsNutrients. the current peripheralperipheral Thus, Antarctica (CCA), which surrounds the Great White Continent, plays a major role in exchanges with other ocean basins, affecting Atmospheric circulationAtmospheric circulation And the climateclimate Total.

The formation of plate tectonics developed as a precursor to the Antarctic Current

However, the origin of this stream, currently the largest on Earth, is still not well understood. Its beginning has long been associated with a development in organization Tectonic platesTectonic plates Opening two sea lanes DrakeDrake Between South America, Antarctica, and Tasmania.

Thus the tectonic isolation of Antarctica would have allowed the initiation of this great current, which would then have acted as a barrier preventing any supply of energy. heatheat of warm tropical waters, ensuring the permanent glaciation that began 34 million years ago.

The strengthening of the current is associated with a cooling of the climate

A scenario modified by a new published study In the magazine Natural earth sciences. Analysis of small teeth PiscesPisces ExcavationsExcavations found in SedimentsSediments Sailors from the Southern Ocean have shown, in addition to measuring the grain size of these sediments, that if the openings of the Drake Passages and Tasmania had indeed allowed the initiation of the Antarctic Circumpolar Current, it would not have initially had its current characteristics. In fact, the study shows that it was only 14 million years ago that the current gained the strength and reach that characterizes it today. This strengthening, which would therefore have occurred about 20 million years later than previously thought, would be linked to global hydrological and meteorological changes resulting from cooling of the Earth's climate.

These results highlight the fact that if ocean currents influence climate, the opposite is also true. It could also make it possible to better constrain models of the evolution of this current in the face of current global warming.