The Champagne region is a popular tourist destination. Today's highlights - the rolling hills and gastronomic delights - did not exist during the Eocene, some 45 million years ago. Much of what is now northern France was underwater and a climate similar to the Bahamas prevailed.
Detailed image from millions of years ago
A Belgian-Dutch research team, led by KU Leuven, made an unprecedentedly detailed reconstruction of the climate in western Europe 45 million years ago. The researchers analysed the fossil shell of Campanile giganteum, a huge extinct sea snail that grew exceptionally fast, leaving a very precise archive of the climate in its shell. Carbonate measurements show that Western Europe at that time experienced monsoon-like conditions: mild winters, hot and dry springs, and hot and especially wet summers with intense rainfall.
"Because this fossil sea snail grew so exceptionally fast, we can extract a lot of information from the shell. Using the growth lines, we get a detailed picture of the climate and weather patterns millions of years ago," says first author Nick Van Horebeek, who researched the shell for his master's thesis at KU Leuven. "By linking our own analysis to climate models, we saw that the pronounced seasonal differences could be explained by shifting wind and ocean circulation patterns."
Understanding seasons and weather in warmer climates
Co-author, VU Amsterdam earth Scientist Niels de Winter adds: "I remember well when Johan Vellekoop and I started studying these giant snails. We thought: Such a large shell must have been made by a very old animal and therefore yield a long climate archive. Nothing could be further from the truth, because these snails grew incredibly quickly! Such a fast-growing shell gave Nick enough material to accurately unravel the climate of the distant past down to the day, which is almost unprecedented in geology. This way, we learn not only that increased CO2 concentrations lead to warmer climates, but also what the seasons and even the weather may look like in such a warm climate. Much remains unclear about this."
Worst-case scenario
The Eocene was an era, from 56 to 33.9 million years ago, with a distinctly warm and wet climate, as well as very high CO2 concentrations. Better knowledge of the climate back then can therefore be of great value to better assess the consequences of current and future climate change. "The Eocene acts as a natural experiment that shows us how the climate system responds to very high CO2 concentrations," Johan Vellekoop, head of the research team and professor of geology at KU Leuven and affiliated with the Institute of Natural Sciences, points out.
"If we do not counteract climate change and allow greenhouse gas emissions to rise, Western Europe may end up back in the Eocene scenario in a few hundred years. On the other hand, if we learn the right lessons from the past, it need not come to that."
The study is published in Nature Communications.
Photo by Johan Vellekoop.
