The Indian Institute of Technology, Kharagpur (IITKGP) has found new evidence for the popular hypothesis that climate change caused human migration during and after the collapse of the Indus Valley Civilisation (IVC).

Findings of the study:

  • The evidence from the sites at Karim Shahi in the GRK and Vigakot in Thar proves that human habitation continued in the region up to the Early Medieval Period.
  • Evidence from unearthed pottery established that the inhabitants of the IVC slowly moved from the Indus valley sites in the west into the Ghaggar-Hakra valley in the east.
  • The shifting of the ITCZ : 
    • Led to the drying up of rivers which made agriculture rather difficult.
    • Forced people to migrate for greener pastures.

Climate migration:

  • Causes of climate migration:  A wide variety of social, political, economic and other environmental reasons and all are interconnected.
  •  IPCC findings: According to the Intergovernmental Panel on Climate Change (1990) the single greatest impact of climate change will be on human migration. 
  • In 2016, about 24 million people were instantly displaced by the sudden onset of climate events like cyclones and floods but there is very little evidence to inform about the number of people migrating due to slow-onset events like drought and desertification.
  • (2011-15) drought-induced armed conflicts caused asylum-seeking and migration.


  • The Inter-Tropical Convergence Zone, or ITCZ, is a belt of low pressure which circles the Earth generally near the equator where the trade winds of the Northern and Southern Hemispheres come together. 
  • It is characterized by convective activity which generates often vigorous thunderstorms over large areas. It is most active over continental landmasses by day and relatively less active over the oceans.
  • The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums or the calms because of its monotonous, windless weather, is the area where the northeast and southeast trade winds converge. 
  • It encircles Earth near the thermal equator, though its specific position varies seasonally.

The decline of IVC ( Indus Valley civilization)- Probable reasons:

  •  It is believed that the drying up of the Saraswati River, a process that had begun around 1900 BCE, was the main cause.
  • Invasion of Aryans from Central Asia.
  • Climate Change