Climate Change Led to Collapse of Ancient Indus Valley Civilization

The Indus or Harappan Civilization thrived in the northwestern parts of South Asia more than 4,000 years ago. The ancient society that developed mainly in the Indus River Valley was marked by the construction of sophisticated cities and advanced culture.

During 1800 BCE, the Indus Civilization abandoned large cities. They settled in smaller villages in the Himalayan foothills and eventually disappeared. A new study provides evidence that ancient Indus civilization disintegrated in response to climate change. A shift in temperatures and weather patterns over the Indus valley caused by monsoon rains to gradually dry up. The rainfall reductions made difficult farming impossible near Harappan cities and forced people to resettle far from the river flowing.

"Although it was difficult to digest along the Indus, it was more often in the foothills," said Liviu Giosan, a geologist at the Woods Hole Oceanographic Institution (WHOI). "As winter storms from the Mediterranean hit the Himalayas, they created rain on the Pakistan side, and fed little streams there. Compared to the floods, the Harappans were used to the Indus, it would have been relatively little water, but at least it would have been reliable. "

Finding direct evidence of this shift is difficult. Pakistan's coast Pakistan off coast. They examined the shells of single-celled plankton called foraminifera that they found in the sediments and uncovered deeper clues about region's climate.

"The seafloor near the mouth of the Indus is a very low-oxygen environment, so any grows and dies in the water is very much preserved in the sediment," said Giosan. "You can only get fragments of DNA from anything that's lived there."

Analysis revealed that strong winds bring nutrients from the ocean to the surface, feeding a number of plant and animal life during winter monsoons. Weaker winds, on the other hand, provide less nutrients rest of the year, slightly less productivity in the offshore waters.

"The value of this approach is that you have a record of having lost a fossil record. William Orsi, paleontologist and geobiologist at the Ludwig Maximilian University of Munich, said.

Researchers believe that the collapse of Indus Civilization occurred gradually. The rains in the foothills seem to be more important, but they would eventually dry up and contribute to their ultimate demise.

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