As geological puzzles go, it is pretty good. In the global greenhouse conditions of the early Eocene (56-48 million years ago), how were the large number of giant glendonite crystals formed?
The rare crystalline calcium carbonate – which requires temperatures below 4 degrees Celsius to form – is composed of the mineral ikaite and is found in their tens of millions on the Danish islands of Fur and Mors. They were dated 56-54 million years ago.
“Why do we find glendonites from a hot season, when temperatures above 35 degrees, have long been a mystery,” said geologist Nicolas Thibault, from the University of Copenhagen in Denmark. “It should not be possible.”
After a detailed chemical analysis of Thibault̵7;s glendonite samples and an international team of researchers, using a technique called clumped isotope thermometry to track temperatures back millions of years, we can come up with an answer : the Eocene is probably not as hot as previously thought.
The idea of cooler Eocene spells has been passed down before, but the evidence is uncertain so far. The new chemical degradation helps researchers discuss the case for colder conditions, with models suggesting glendonite formed in waters below 5 degrees Celsius (41 degrees Fahrenheit) at depth which is about 300 meters (984 feet).
The sedimentary layers of ash on the island of Fur point to the possibility that volcanic eruptions may be responsible for these chillier episodes in the Eocene, which are localized around specific regions, which help to explain the colder. water and the rock record.
“There are probably a large number of volcanic eruptions in Greenland, Iceland and Ireland during this period,” Thibault said.
“They release droplets of sulfuric acid into the stratosfir, which may have remained there for many years, obscuring the planet from the sun and reflecting the sunlight.”
“It helps to explain how cold areas are possible, which is affecting the climate in early Eocene Denmark.”
The new study supports the theory that colder Eocene periods are more likely than the successor – which science is wrong about the type of temperature formed in the rock based on ikaite.
Next, the team wanted to see similar investigations conducted to see how widespread cooling was discovered in the Danish Basin actually. Other geological records – including those from the Arctic – suggest that this temperature drop does not occur worldwide through the Eocene.
Like any discovery about our past climate, the study will help scientists visualize our climate in the future.
We may not have killed the volcanic ash sky anytime soon, but a rapid climate change is something we are going through – like parts of the world more than 50 million years ago, before whether people come to the scene.
“Our study helps solve a mystery about glendonites, as well as showing that cooler stages are possible during otherwise warmer climates,” Thibault said.
“The same can be said for now, as we prove the possibility of sudden climate change.”
The research was published in Communications in Nature.