Thursday , July 7 2022

Climate change is likely to cause migration, disappearance of ancient Indus Valley civilization


Credit: CC0 Public Domain

Over 4,000 years ago, the Harappa culture flourished in the Indus Valley of what is now in modern Pakistan and in northwestern India, where they build sophisticated cities, have devised former sewage systems in ancient Rome, and take part in long distance trade with settlements in Mesopotamia. Yet, by 1800 BCE, this advanced culture had left their cities, moving instead of smaller villages in the Himalayas wars. A new study of the Woods Hole Oceanographic Organization (WHOI) found evidence that climate change is likely to defeat Harappans to reset well away from Indus floodplains.

Around 2500 BCE began, a change in temperatures and weather patterns over the Indus valley caused the summer mound to dry out gradually, making agriculture difficult or impossible near the cities of Harappan, says Liviu Giosan, a geologist at WHOI and lead author of the paper published on November 13, 2018, in the magazine Climate of the Past.

"Although the summer whales can make agriculture difficult throughout the Indus, the moisture, the moisture and the rain would become more regular," said Giosan. "As the winter storms of the Mediterranean arrived at the Himalayas, it created rain on the side of Pakistan, and it was fed from small streams there. In comparison to the flood from Marshs used the Harappans to see in the Indus, it would have been relatively small water, but at least it would have been reliable. "

There is evidence of this seasonal rain change – and the Harapans change depending on Indus flooding to rainfall near the Himalayas for crop water – is difficult to find soil samples. That's why Giosan and his team focus on sediments from the seashore off the Pakistan coast. After taking core samples in several sites in the Arab Sea, he examined a group of plankton shells one cell of the name foraminifera (or "forams") found in the sediments, helping them to understand which some who were thriving in summer, and who are in the winter.

Once he and the season identification team were based on the fossil remains of the forams, they could then concentrate on deeper clues to the area's climate: paleo-DNA, extracts of deposited ancient genetic material .

"The sea bed near the Indus mouth is a very low oxygen environment, so anything that grows and dies in the water has a very good detention in the sediment , "said Giosan. "Basically, you can get DNA pieces of almost anything that's there."

During the winter mountains, it indicates, strong winds bring nutrients from the deeper sea to the surface, feeding surge in the life of plants and animals. Similarly, weaker winds of other times of year provide less nutrients, causing a little less productivity in the waters at sea.

"The value of this approach is that it gives you a picture of the physical biodiversity that you would lose by relying on skeletal residues or fossil record. And because we can arrange billions of DNA bugs on the co, a picture of how the ecosystem has changed over time, "added William Orsi, paleontologist and geobiologist at the University of Ludwig Maximilian, Munich, who collaborated with Giosan at work.

Certainly, based on evidence of the DNA, the couple found that winter monsters appear stronger – and summer mites are weaker-towards the later years of Harappan civilization, which is 39 ; n match the move from cities to villages.

"We do not know if Harappan caravans were moving towards the cattle within a few months, or this massive migration was over centuries. What we know is when it came to an end, their urban lifestyle came to an end," he said Giosan.

The rainfall in the war seems to have been enough to hold the rural Harapans over the next millennium, but those who eventually dried would probably contribute to their ultimate decline.

"We can not say they are completely disappearing due to the climate – at the same time, the Indo-Aryan culture reaches the region with Iron Age and horses and carts, but it's very similar that the winter mound plays a role, "Giosan said.

The great surprise for the research, Giosan notes, is how far the roots of climate change have been. At the time, "new ice age" settled down, enforcing air cooler from Atlantic to Atlantic and northern Europe. In turn, storms pushed down into the Mediterranean, leading to cover in the winter mountains over the Indus valley.

"It's really amazing, and there's a powerful lesson today," it's not. "If you look at Syria and Africa, the migration out of those areas has some roots in climate change. Only the rise at sea level that comes from climate change and which can lead to massive migrations from low regions such as Bangladesh, or from a hurricane of light regions in the southern United States. Accordingly, Harappans could cope with change by moving, but today, you'll run to all types from boundaries. Then political and social convulsions can follow. "

Further investigation:
Researchers collect that climate change leads to the decline of ancient Indus civilization

Magazine reference:
Climate of the Past

Provided by:
Oceanographic Hole Woods Foundation

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