Excavations at the bottom of the Indian Ocean have helped climatologists find new evidence that the legendary first civilization of the Earth in the Indus Valley has disappeared due to a sharp change in climate and rainfall patterns. Their findings were published in the journal Climate of the Past.
“The history of the Indian civilization is a good lesson for all of us. Look at Africa or Syria - people are leaving because of similar climate changes. In the past, people could cope with similar problems by moving to another place, but what to do today for the residents of the southern US and the coast of Bangladesh, who may soon be flooded by the sea?”- said Liviu Giosan of the Oceanographic Institute in Woods -Houl (USA)
The Indian, or Harappan, civilization is one of the three most ancient civilizations, along with the ancient Egyptian and Sumerian. It originated about five thousand years ago in the Indus Valley on the border between modern India and Pakistan and reached its heyday in 2200-1900 BC.
During this period, a system of intercity and "international" trade emerged, planning of urban settlements, sanitary facilities, measures and weights were standardized, and the influence of the Indian civilization spread to the entire subcontinent.
After 1900 BC, it began to decline, disappearing without a trace after several centuries - the megacities of the ancient Indians were deserted, and their tribes moved to small villages at the foot of the Himalayas. Many historians and archaeologists associate her death with climate change in the region, which, due to the weakening of the monsoons, became colder and drier at the beginning of the second millennium BC.
On the other hand, recent data on the Earth's climate over the past ten thousand years show that the climate of Hindustan has radically changed in earlier historical eras. This makes scientists argue about why the Harappan civilization did not disappear earlier and how droughts, disappearing rivers and other climatic disasters really affected it.
Archaeological excavations at the site of the city of Rakhigarchi in India.
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Josan and his colleagues tried to resolve these disputes by conducting excavations not on the territory of Mohenjo-Daro, Rakhigari and other centers of the Indian civilization, but at the bottom of the Indian Ocean, in different parts of the Pakistani coast.
The fact is that deposits of plankton shells, molluscs and other types of sedimentary rocks are a kind of climatic "chronicles", which very clearly reflect how the Earth's climate changed at the time when they were formed.
For example, the proportions of "heavy" and "light" oxygen isotopes can tell us about temperature fluctuations on Earth, the concentration of "heavy" carbon - about biodiversity and the presence of mass extinctions, and the proportion of calcium and a number of other metals - about the level of acidity of waters and other properties. of the world ocean.
Using this information, as well as scraps of DNA from this plankton, scientists were able to track how much fresh water entered the coastal ocean waters, and how the level of precipitation changed during winter and summer.
As these observations showed, the end of the Harappan civilization was associated not with the onset of drought, but with the fact that the nature of precipitation had radically changed - winter monsoons became even more abundant, and summer rains began to fall less and less frequently. This did not change the total rainfall that much, but made the Indus Valley almost uninhabitable for large groups of people inside large cities.
Such changes, in turn, were associated with the fact that the climate at that time was entering the next "Little Ice Age", which lowered temperatures in all corners of the planet. This cooling gradually changed the nature of the movement of winds and currents in the Indian Ocean, which was one of the key factors in the disappearance of the first civilization on Earth, scientists conclude.