About 4,000 years ago, Harappa culture flourished in the Indus River Valley in contemporary Pakistan and northern India. They had a large and affluent city, created a sewer in front of the Romans, and established a wide trade route to Mesopotamia. In less than two centuries, however, their culture has faded, the city has shrunk, and the main cause is climate change.
The Indus Valley civilization was mainly urban culture maintained by surplus agricultural production and commerce. They preferred urban settlements and built at least two major cities: Harappa and Mohenjo Daro.
But things began to change from 2500 BC. Agriculture has become increasingly difficult because the summer monsoon gradually dries up depending on temperature and weather conditions throughout the Indus Valley.
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Liviu Giosan, WHOI geologist and author of a new book, said that this ultimately led to his end and slowly retreated to a small town at the foot of the Himalayas.
"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." It rained in Pakistan, which hit the Himalayas in a winter storm in the Himalayas. It might have been relatively little water compared to the monsoon floods Harappans had been accustomed to seeing in Indus, but at least it is credible. "
The end of the age
This is not a new theory, but evidence of this pattern of change was difficult to find in soil specimens. Instead, Giosan and his colleagues went to the sea. They saw a fine fossil. Foraminifera. Foraminifera is a primitive "living fossil" that lives in the Cambrian (542 million years ago) to this day. They usually have fossils made of calcium carbonate, which often means fossilized in the environment of the Indus region. But researchers found DNA fragments instead of finding fossils.
"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."
"The value of this approach is to provide a picture of the past biodiversity that will be missed by relying on skeletal remains or fossil records, and because we can arrange billions of DNA molecules in parallel, "In collaboration with Giosan, William Orsi, a paleontologist and biogeographer at Munich's Ludwig Maximilian University, adds: .
It is an interesting type of indirect evidence: strong winds of the monsoon season in winter bring the nutrients from the depths of the sea to the surface, increasing the life of plants and animals. The evidence of this bibliography is recorded in the sediments below. The seabed. According to DNA evidence, the winter monsoon becomes stronger and the summer monsoon becomes weaker towards the end of Haraffan civilization and moved from town to town. It is not clear exactly when and how soon this process was, but it was the end of the era.
"We do not know if the Harappan caravan has moved to the foothills in months, or whether this massive movement has occurred over the centuries, and what we know is that their urban lifestyle is over when they come to a conclusion," Giosan Says.
Lessons for today
This event represents an important warning today. Unlike us, the Harapans have not brought about this climate change themselves. The cause of this climate change is actually coming from far away. The mini ice age settled, releasing cooler air from the Arctic to the Atlantic and further to the north. This time, the winter monsoon of the Indus Valley soared as the Nordic cold weather (relatively warm air) was pushed and a storm hit the Mediterranean Sea. The domino pieces fell noticeably and caused a flame. Destiny for Harappan city.
Similar processes are taking place today, and climate change is creating a complex mechanism that will affect all regions on the planet.
"What is noteworthy is today's strong lesson." Looking to Syria and Africa, migrating from the region is rooted in climate change. This can lead to massive movements in low-lying areas such as Bangladesh or hurricane-prone areas in the southern United States, due to early sea level rise due to climate change. At that time, Thalapain was able to cope with the change due to the movement, but you will cross all kinds of borders. This can lead to political and social cramps. "
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