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Climate change is likely to have caused the migration and end of the ancient Indus Valley civilization.


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4000 years ago, Harappa culture flourished in the current flourishing Pakistan and India northwestern regions of the Indus River valley, building a sophisticated city, inventing a sewer system that overthrew ancient Rome, and trading with settlements in Mesopotamia over long distances. However, until 1800 BC, this advanced culture moved to a small town at the foot of the Himalayas and abandoned the city. A new study by the Woods Hole Oceanographic Institution (WHOI) found evidence that climate change can resettle Harappan away from the Indus Valley floodplain.

The change in temperature and weather patterns in the Indus Valley, which began around 2500 BCE, caused the summer monsoon rain to gradually diminish, making agriculture difficult or impossible near the city of Harappan, according to WHOI geologist Liviu Giosan. Posted in the journal on November 13, 2018 Past climate.

"With the volatile summer monsoon, agriculture became difficult along the Indus River, but at the foot of the mountain, moisture and rain rose more regularly." "In the Mediterranean, there was a winter storm that hit the Himalayas and rained down to Pakistan, and there was hardly any water in it." Haradin was accustomed to see the Indus River, but compared to the monsoon flood, Trustworthy. "

There is evidence that this change in seasonal precipitation and the difficulty of converting Harapans to soil samples for rain harvest near the Himalayas in the Indus River basin. So Giosan and his team focused on sediments from the seabed of the Pakistani coast. After collecting key samples from several locations in the Arabian Sea, he and his team studied the foraging of the unicellular plankton called foramsifera (or "forams") found in sediments to understand what flourished in summer One winter to help.

After he and the team identified the seasons based on the fossil debris of the toms, they could focus on deeper clues about the climate of the area: paleo-DNA, a fragment of ancient genetic material preserved in sediments.

"The undersea near the mouth of the indus is very low in oxygen, so whatever it grows or dies in the water is well preserved in the sediment," Giosan says. "Basically you can get almost any piece of DNA that lives there."

During the winter monsoon season, strong winds bring nutrients from deeper waters to the surface, resulting in a surge in plant and animal life. Likewise, weak winds at different times of the year provide a small amount of nutrients, which slightly reduces the productivity of overseas waters.

"The value of this approach is a solution to how the ecosystem has changed over time, because it shows the past biodiversity to be missed by relying on skeletal remains or fossil record, and it can arrange billions of DNA molecules in parallel "Added William Orsi, a paleontologist and biogeographer at Ludwig Maximilian University in Munich who worked with Gioan.

Of course, according to evidence of this DNA, these two men seemed to be stronger and weaker in the summer monsoon season as the winter monsoon moved from city to town to the latter part of the Harper civilization.

"We do not know whether the Harappan caravan has moved to the foothills in months, or whether huge migrations have occurred over the centuries, and the conclusion of the city's lifestyle is over," Giosan says.

The rain at the foot of the mountain will eventually dry up and ultimately contribute to the ultimate end, even though it was enough to take over the rural Harapans for the next year and a thousand years.

"At the same time, the Indo-Aryan culture arrived in this area with Iron Age tools, horses and wagons, but it is likely that the winter monsoon played an important role," says Giosan. .

Giosan was very surprised at the extent to which the roots of climate change were far apart. At that time the "New Ice Age" forced cold air from the North Pole to the North Atlantic. As a result, the storm was pushed to the Mediterranean Sea, leading to the winter monsoon rise of the Indus Valley.

"What is remarkable is a powerful lesson today." Looking at Syria and Africa, migration in this region is rooted in climate change. This can only lead to massive migrations, such as lowland areas or hurricanes, such as Bangladesh, due to sea level rise due to climate change. At that time, the Harapans could move and cope with change, but today they will encounter all kinds of borders and political and social cramps. "

Additional information:
The researchers concluded that climate change has led to the collapse of ancient indus civilization.

Journal Reference:
Past climate

Provided by:
Woods Hall Marine Research Institute

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