Approximately 80,000 years ago, when the last ice age began on Earth, an unknown anomaly occurred. According to new research, the level of the world’s ocean, which has been falling for thousands of years (this is normal for the Ice Age, as more and more water was concentrated in the spreading glaciers) suddenly increased. Then, in a relatively short time, the water level rose again. Researchers have not yet found the cause of this phenomenon, they say that the results obtained may cause a partial revision of the mechanisms controlling the Earth’s climate.
In the past, stable climatic cycles have taken place on our planet for several hundred thousand years. That is, every 100,000 years, many kilometers of glaciers formed in the northern latitudes of North America, Europe, and Asia and deeply stretched in the middle of latitude. These glaciers concentrated in themselves such volumes of water that the level of the world ocean could drop by more than 100 meters. Then for about 90,000 years, the glaciers retreated, and the earth was again freed of ice until another glacial period began. The last ice age ended about 11,000 years ago.
Various scientists, returned to the study of the causes of these cycles for almost a century. During this time, several factors have been put forward:
- periodic changes in the Earth's orbit,
- oscillation axis of rotation of our planet.
But so far no definitive answer has been found on this issue. With their new discoveries, researchers are undermining their former confidence in the study of the behavior of the glacial cycle. What they found is a very convincing proof of this - because when the Earth was supposed to be at the apogee of the last ice age, the seas flourished.
In the coastal caves on the Spanish island of Majorca in the Mediterranean, a team of researchers studied calcite-covered stalactites. They measured the levels of these layers, which noted the minimum and maximum levels of water and made their radiocarbon analysis. Based on the data obtained, it was found that 80,000 years ago the sea level returned to the former, while it was 1 meter higher than at present. The increase in the level most likely occurred fairly quickly - about 2 meters per century, says geochemist and scientific adviser Jeffrey Dorale of the University of Iowa, Iowa City.
This means that the glaciers melted at a tremendous rate. Even half of that speed would be a “major discovery,” says Dorale. Thus, now "there is basic data for studying probable problems with sea level changes."
Geologist and coauthor Bogden Onek of the University of South Florida (Tampa), says that he and his colleagues Angel and Joaquin Hines of the University of the Balearic Islands, even in the distant 70s of the last century, suspected that the growth levels of Majorcan stalactites are very important, but then there wasn’t technology, with which it was possible to determine their age with high confidence.
The study "provides convincing evidence" of a sharp rise in sea level about 80,000 years ago, says geologist Daniel Max of the American Geological Survey in Denver, whose own work in the Bermuda area showed a similar result. Other data from Barbados and New Guinea also confirm the results obtained, although there the rise in sea level was not so great. This means, says Max, “that there are many more factors affecting the change in the sea level that we still don’t know about.”