Climate change killed Harappan civilization: Study

Climate change may be the main culprit behind the collapse of the Indus Valley Civilization around 4,000 years ago, says a new study, which also claims to have resolved the long-standing debate over the source and fate of the Saraswati, a sacred river in Hindu mythology.

The study, combining the latest archaeological data along with state-of-the-art geoscience technologies, suggested that decline in monsoon rains led to weakened river dynamics, and played a critical role both in the development and the fall of the Harappan culture, which relied on river floods to fuel their agricultural surpluses.

The international team, which published their findings in the journal Proceedings of the National Academy of Sciences, used satellite photos and topographic data to make and analyse digital maps of landforms constructed by the Indus and other neighbouring rivers, which were then probed in the field by drilling, coring, and even manuallydug trenches. Collected samples were used to determine the sediments' origins, whether brought in by rivers or wind, and their age, in order to develop a chronology of landscape changes.

"We reconstructed the dynamic landscape of the plain where the Indus civilization developed 5,200 years ago, built its cities, and disintegrated between 3,900 and 3,000 years ago," said lead researcher Liviu Giosan, a geologist with Woods Hole Oceanographic Institution in the US. "Our study suggests that the decline in monsoon rains led to weakened river dynamics , and played a key role both in development and the fall of Harappan culture," he said.

The research, which was conducted between 2003 and 2008, also claimed that the mythical Saraswati river was actually not fed by glaciers in the Himalayas as believed. Rather, it was a perennial monsoon-supported watercourse and aridification reduced it to short seasonal flows, the researchers said.