The latest phase in our planet’s history, the one in which we’re living right now, has been officially designated as the Meghalayan Age, Newsweek reports.
The announcement comes from the International Commission on Stratigraphy (ICS), which has proposed that the Holocene, the current geological epoch of the Earth, be divided into three separate stages, marking the epoch’s lower, middle, and upper phases. The Meghalayan Age is now the youngest of the three phases, stretching from 4,200 years ago until the present time.
The decision is based on geological and chemical data pointing to a planet-wide climatic event that triggered the Meghalayan Age and impacted not only Earth’s climate, but also the ancient human civilizations that were inhabiting the planet at the time.
ICS’ proposal comes after more than a decade of study into the Quaternary Period — the most recent period of the Cenozoic Era and which encompasses the Pleistocene and the Holocene Epochs — and has been officially approved by the International Union of Geological Sciences (IUGS), notes the BBC.
These latest modifications are now to be included in the International Chronostratigraphic Chart, the diagram that depicts the timeline of our planet’s history, describing all of Earth’s eons, eras, periods, epochs, and ages.
The Holocene Epoch
The Holocene Epoch comprises the last 11,700 years of our planet’s 4.6-billion-year history. This latest geological epoch of Earth started with a global warming event that pushed the planet out of the last Ice Age.
The first stage, or the lower phase, of the Holocene is now being described as the Greenlandian Age, which lasted for 3,400 years, from 11,700 years ago until 8,300 year ago, when another major event changed the planet’s climate.
Then came the Northgrippian Age — the middle phase of the Holocene, lasting for 4,100 years — which kicked off 8,300 years ago with a planet-wide cooling event. Just like the Greenlandian Age, the Northgrippian Age has been defined after the study of ice cores in Greenland, which revealed the boundary between the Holocene’s first two stages.
The Northgrippian Age was brought about by the melting of Canada glaciers during the Greenlandian warming period, which released massive volumes of freshwater into the North Atlantic, disrupting ocean currents and cooling the climate.
The latest version of the International Chronostratigraphic Chart/Geologic Time Scale is now available! New #Holocene subdivisions: #Greenlandian (11,700 yr b2k)#Northgrippian (8326 yr b2k)#Meghalayan (4200 yr before 1950) https://t.co/IhvZHfHnWh#ChronostratigraphicChart208 pic.twitter.com/8Pf9Dnct7h— IUGS (@theIUGS) July 13, 2018
The third and last phase of the Holocene, now known as the Meghalayan Age, propelled the planet into another warming stage, and actually started out with a global drought that lasted for two centuries.
“The units represent a highly refined record of the evolution of surface environments of the Earth System, which, in turn, provide a basis for evaluation of the nature of the climate change occurring today,” said IUGS secretary general Stanley Finney, who is a professor of geological sciences at Long Beach State University in California.
The Meghalayan Age
First described in a scientific paper published six years ago in the Journal of Quaternary Science, the Meghalayan Age has been identified from geochemical analyses conducted on stalagmites in a cave in the Meghalaya state of India — from where this latest chapter in Earth’s history actually draws it name.
Research into the layers of the stalagmites that cover the floor of Mawmluh Cave uncovered a disruption into the isotopes of oxygen atoms contained within the rock formations, which points to a shift from monsoon weather conditions to a drier environment.
“In these stalagmites there is a very highly detailed record of climate change, which is shown by the geochemistry of the precipitated material — the carbonate formed by the dripping of water in the cave,” ICS secretary general Philip Gibbard said in a statement.
According to Prof. Mike Walker of the University of Wales in the U.K., the shift in oxygen isotopes indicates that monsoon rainfall decreased by 20 to 30 percent. This revealed that the planet experienced yet another massive change in its climate about 4,200 years ago, particularly at mid and low altitudes.
“The two most prominent shifts occur at about 4,300 and about 4,100 years before present, so the mid-point between the two would be 4,200 years before present, and this is the age that we attribute to the [Meghalayan golden spike],” explained Walker, who led the international team of Holocene scientists that developed the proposal for the epoch’s division.
Unlike the other intervals in the planet’s geological timescale, the Meghalayan Age also coincided with a major cultural event, caused by the severe drought at the beginning of this last Holocene phase. In this particular case, the global climatic event that set off the start of the geological age also produced a global cultural event which impacted the ancient civilizations in Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus Valley, and the Yangtze River Valley.
What About The Anthropocene?
Although the Meghalayan classification has already been made official, some scientists argue that it may have been premature to place it on the diagram, report the sources.
For instance, Mark Maslin, who is a professor of geography at University College London in the U.K., believes that this latest division of the Holocene should have taken into account all the research that is currently being done with the objective of defining another geological era in Earth’s history, namely the Anthropocene.
As the Inquisitr previously reported, the Anthropocene is meant to describe the human impact on the planet’s geological record, marking the beginning of anthropogenic climate change.
“We have lots of new definitions that perhaps now contradict the Anthropocene Working Group and go against what most scientists perceive to be the most important change on Earth in the last 10,000 years,” said Maslin.
However, Walker points out that the newly-established Holocene subdivision don’t come into conflict with a future designation of the Anthropocene.
“These subdivisions of the Holocene are based entirely on physical (climatic/environmental) evidence whereas any designation of the Anthropocene as a new unit within the geological timescale would rest entirely on evidence for human impact,” said Walker.