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The Earth has entered a new geological age, that of Meghalayan. A unique subdivision among the many stages of the geologic time scale as it would be linked to an event of human origin.
Scientists have defined a new chapter in the history of the Earth and what it contains concerns us first and foremost. The International Stratigraphy Commission (ICS) proposed that the Holocene, a geological period that began 11,700 years ago with the end of the great glaciation of the northern land hemisphere, be divided into three distinct periods: the Greenlandian, Northgrippian and Meghalayan.
The first coincides with the end of the Ice Age and is between 11,700 to 8,200 years before the present. The second is motivated by cooling attributed to large volumes of freshwater from melting glaciers that have disrupted ocean currents. It is between 8,200 and 4,200 years before the present. These two stages were defined following the study of the Greenlandic ice cores which made it possible to delimit them.
"These stalagmites contain a very detailed record of climate change, which is indicated by the geochemistry of the precipitated material – carbonate formed by drops of water in the cave" says Philip Gibbard, secretary General of the ICS, in a statement
A first
As for the last, the Meghalayen, it extends from 4,200 years to today. The beginning of this new age of the Earth is marked by the occurrence of a great drought coupled with an abrupt cooling of the climate. So many climatic changes have contributed to the weakening of many civilizations in Mesopotamia, China, India, Egypt and Greece.
According to Pr. Mike Walker, who led the team of scientists to the origin of the division, the change in isotopes contained in oxygen indicates that the monsoon rains have decreased from 20% to 30%. This study revealed that the planet experienced yet another mbadive change in its climate about 4,200 years ago, especially at low and medium altitudes.
"These two major changes occur between 4,300 and 4,100 years ago before the present, so that the median age would be 4,200 years before the present, so this is the age we attribute to the Meghalayen " he explains on the BBC website. This age is unique among the many intervals of the geological time scale because it is related to a global event badociated with human history, resulting from a major climatic event. This is the first time that the CIS has taken into account a cultural event to define a period.
An age that is already under debate
This new subdivision is however a debate within the scientific community. Some researchers believe that its entry into the chronostratigraphic diagram, which represents the chronology of the history of our planet, is premature. While others claim that we have already entered the Anthropocene, the global impact of human activities on the Earth's ecosystem is significant.
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