Temperatures in the depths of the North Atlantic were once 20 degrees Celsius, warmer than the surface of the modern Mediterranean, according to a new study of ancient ocean temperatures, published today in science,show.
Scientists say new data spanning the past 60 million years shows huge impact of higher carbon dioxide emissions2 past geological levels and highlight the urgent need to avoid persistent CO2 The future rises.
“Today, the deep ocean is filled with icy water,” said study co-author Dr James Ray from the University of St Andrews. “But 50 million years ago, it was as warm as the Mediterranean is today.”
Chemical
An international team including scientists from Norway, the Netherlands, Switzerland and the United States used chemical fingerprints of tiny fossil shells from deep-sea mud cores to reconstruct ancient ocean temperatures.
Using state-of-the-art new laboratory measurements, they were able to obtain the most accurate temperature estimates to date, showing that temperatures are warmer – and more variable – than previously thought.
Professor Nell Meckler from the University of Bergen, who led the research, explained: “We looked at the way different carbon and oxygen atoms came together in these ancient shells, and it turned out to be a very accurate Calculations. The temperature at which the shells formed.”
Dr Phil Sexton, co-author of the Open University study, added: “Due to the continuous buildup of mud and shells on the seabed, the 3km long tube of mud acts like a time capsule.
“As you go deeper into the core, the fossilized shell gets older, and by measuring shell chemistry, we can get a long-term record of past climate change.”
Transform
The 20 degrees Celsius temperature deep in the North Atlantic comes from a period called the Eocene, about 15 million years after the extinction of the dinosaurs, when atmospheric carbon dioxide2 About three times as much as today.
While previous fossil indicators suggested this period was marked by extreme temperatures, with palm trees and crocodiles inhabiting the Arctic, new research suggests that this extreme warmth is also felt deep in the ocean.
Dr Rae said: “These ancient greenhouse climates may seem a far cry from today, but they are crucial in helping us understand the effects of carbon dioxide2 About climate change. “
He added: “Although these ultra-hot greenhouse climates happened a long time ago, they are crucial in helping us understand the impact of carbon dioxide.2 about future climate change.
“Carbon monoxide2 It has changed the face of our planet before, and it will do so again unless we limit emissions soon. “
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Brendan Montague is the editor of The Ecologist. This article is based on a press release from the University of St Andrews.
