Mud cores extracted from Mississippi have provided fresh insights into the formation of vast Antarctic ice sheets approximately 34 million years in the past.
The Mississippi mud core drills open a window to Antarctica’s massive ice sheet formation 34 million years ago.
In a significant find, mud cores extracted from Mississippi have provided fresh insights into the formation of vast Antarctic ice sheets approximately 34 million years in the past.
From Warm to Cold
Earth’s transformation from the tropical Eocene Epoch to the chillier Oligocene revealed that while the Eocene era saw no permanent ice, the initial phase of the Oligocene boasted ice sheets that exceeded today’s size by a whopping 25%.
This ice sheet expansion during the transition between the Eocene and Oligocene epochs caused sea levels to plunge by an impressive 40 meters, revealing vast stretches of land previously under water due to receding coastlines.
The massive sea-level drop triggered significant carbon movement from coastal sediments to the atmosphere, reveals the analysis of the ancient mud sourced from Jackson, Mississippi. “The Mississippi mud has provided answers about Antarctica’s monumental ice expansion,” says Tom Dunkley Jones from the University of Birmingham, UK.
The formation of these ice sheets is attributed to carbon’s long-term burial in sediments, ensuring its removal from the atmosphere where it intensifies heat retention.
This reduced carbon in the atmosphere initiated Earth’s transition to the cooler climate we’ve experienced for the past 34 million years. This led to the growth of large Antarctic ice sheets, which in turn contributed to a global sea-level drop.
However, this rapid cooling proved too swift for many species, leading to mass extinctions. This period also earns the title “Grande Coupure,” a French term implying a “great cut.”
Dunkley Jones emphasizes, “The transition from the Eocene to the Oligocene is a landmark climatic cooling event that greatly influenced Earth’s chronicles.”
The Counter Effect
Surprisingly, this cooling was counteracted to some extent. The retreating seas exposed vast coastal sediment areas, which were subjected to heavy erosion. The drying of these mangrove-like areas led to the release of large amounts of CO2 by microbes, causing a temporary halt to the cooling trend.
“This CO2 release acted as a brief obstacle to the overall cooling trend, especially around the Mississippi River basin,” adds Dunkley Jones.
While the carbon shift from these sediments didn’t prevent the planet’s cooling trajectory into the Oligocene, it sheds light on the intricate workings of this system.
Kirsty Edgar, another researcher from the University of Birmingham, states, “Our findings offer a unique insight into the close relationship between the Earth’s climate, biosphere, and carbon cycle.”
The research team, having studied marine clays deep at 137 meters, correlated this data with findings from the Pacific Ocean. This correlation helped highlight the sediment accumulation over the long term, allowing them to pinpoint the timeline of the sea-level drop and ice sheet formations.
Edgar concludes, “Recognizing these historical incidents offers a deeper understanding of Earth’s splendidly complex climate and ecological interactions.”
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