The Earth, once upon a time, was nothing more than a muddy world. Indeed, around 650 million years ago, the planet shifted from an icy state to a phase of intense melting. This extreme climatic upheaval, called the era of “ocean plumes” (“plumeworld ocean”), would have radically transformed theatmosphere and the oceans.
Scientists at Virginia Tech University have finally found geochemical evidence of this unique period. These data, engraved in carbonate rocks, show that record levels of carbon dioxide broke the intense cold of the last great ice age. By studying lithium isotopes, researchers were able to identify the composition of meltwater from that era, revealing a separation unprecedented in fresh and salt waters.
During this freezing period, extreme low temperatures sealed the oceans, preventing cycles of evaporation, rain and snow. This situation has slowed rock erosion, a process that consumes carbon dioxide carbone. Deprived of this “sponge“natural, the atmosphere gradually accumulated this gas, until it reached a critical level. Over the millennia, heat ended up dominating and melting the ice caps. But this melting was not uniform. Torrents of fresh water suddenly flowed toward the oceans, forming distinct layers of fresh water on top of salty ocean waters. This stark contrast redefined the exchange of heat and materials in the oceans, in a phenomenon that geologists describe. like a “tsunami reverse”.
The researchers analyzed the lithium isotopes of the rocks to reconstruct this dynamic. These isotopes, present in coastal meltwater, reveal the signature of interactions between fresh and salt water in areas close to the coast, while deeper rocks demonstrate sea water still very concentrated in salt.
This climatic “limit” has opened new perspectives for researchers, who wish to understand how ecosystems and life have adapted to extreme environments. The results of this study, published in Proceedings of the National Academy of Sciencescould shed light on the mechanisms of resilience of life forms in the face of climatic variations.
This teaches us that the Earth has experienced phases of climate change so radical that even our imagination has difficulty conceiving them. The living conditions of this era did not, however, erase all forms of life: on the contrary, they undoubtedly played a role in the evolution of biological resilience.
What is a “muddy world”?
The term “muddy world” refers to a state of the Earth during which the ice is mélange with water, creating a planet covered in mud and melting water. This phenomenon probably occurred at the end of a great ice age, where the Earth, initially covered in ice, suddenly went into a state of partial melting. During this period, vast volumes of fresh water from melting ice flowed into the oceans. This created a separation between fresh meltwater and salty, dense ocean water, forming a sort of muddy layer on the planet. This transition has been accompanied by rapidly rising temperatures and drastic climate changes.
Scientists are interested in this unique state because it illustrates how extreme climatic upheavals can radically transform the oceans and atmosphere, while testing the limits of the resilience of terrestrial ecosystems.
