A discovery of a half a million year old stalagmite rock formation in nothern Spain has helped scientists map the progression of climate change and who predict that a new ice age could be coming to the northern hemisphere.
The stalagmite, named ESP06, was cut from the floor of a cave in the Serra do Courel mountains of north-west Spain’s Galicia province.
The stalagmite was carefully selected by a team of researchers led by Professor Juan Ramon Vidal Romani, 74, from the University of A Coruna.
The team was looking for a stalagmite that formed from a very constant drip with the correct proportions of materials from the ceiling above.
When the researchers finally found the best candidate, they were able to “establish a meteorological evolution of the environment and the fauna outdoors” from periods further back than ever before in Europe through similar techniques.
“This was so it did not leave cutting marks,” explained Professor Romani. “It was cut in thin layers which, thanks to the oxygen and carbon isotopes that revealed temperature and humidity data, the stalagmite showed four interglacial and three glacial periods.”
Carbon dioxide in the layers contains trace information on the vegetation the water filtered through on its way to the cave and is more abundant in warm and wet climates.
A more significant presence of aragonite indicates a drier and warmer time.
Calcite, which is a mineral found in calcium carbonate, indicates a colder and wetter climate.
And if the surface of a stalagmite is dry for a time, it forms darker layers that tell scientists the climate at the time was dry.
“We saw there have been interglacial moments with a temperature that is similar to the current one, and glacial times where the temperatures were around 20 or 30 degrees below zero”, explained Romani.
Studies done in the ice of Vostok in Antarctica have revealed comparable climate data.
“When it is cold in Antarctica, it is cold in Galicia, so these are climate models that are the same everywhere,” said the professor.
He explained that from 135,000 years ago until 15,000 years ago, the planet passed through a glacial period.
“The idea is that about every 15,000 years, the tendency changes, and we are now starting that pendular movement. We know that because the Gulf Stream (a warm ocean current in the Atlantic Ocean originating in the Gulf of Mexico and following the eastern US coastline before forming the North Atlantic Drift and crossing the Atlantic) is starting to lose strength. Some believe it may stop,” said Romani
“At that moment, the climate in Europe and United States will get colder, and a new glacial era will start,” said Romani. “In more or less two centuries, we could start a new glaciation period.”
The cave of Arcoia, where the team selected the stalagmite to be studied, was first explored between 1981 and 1993 and also contains prehistoric animals such as cave bears from around 44,000 years ago.