How climate change may have changed Harappan society, and led to decline of the greatest Civilisation in history

             Map of Harrappan civilisation

         

 Architectural  advancement of Harappan  civilisation 

       

Recent studies indicate that variations in monsoonal rainfall due to climate change may have influenced the decline of the Indus Valley Civilisation.

Key Findings

• According to a study, the pattern of changes in monsoonal rainfall may have led to declining of Indus Valley Civilization.
• At first, a wetter winter monsoon may have led to the expansion and de-urbanisation of the Indus Valley Civilisation.
• Eventually, as the winter monsoon declined the agricultural civilization of rural Harappans also declined.

Chronology of Harappan Civilization

• Harappan civilization is divided into

1. Early Harappan Phase: c. 3500 - 2600 B.C.
2. Mature Harappan Phase: c. 2600 -1900 B.C.
3. Late Harappan Phase: c. 1900 - 1300 B.C.

• The early phase was mostly agrarian, centered on villages;
• The Mature phase was characterised by the development of cities.
• The third phase was one of de-urbanisation where several cities were abandoned.

Harappan conditions

• The study named ‘Neoglacial climate anomalies and the Harappan metamorphosis’ reconstructed the behaviour of the Indian Monsoon for about 6000 years.
• Harappans basically relied primarily on fluvial inundation for winter crops and on rain for summer crops.
• According to the study in the first two phases, the climate was warm and wet due to a stable monsoonal pattern.
• This ensured a surplus of agricultural produce during these phases, slowly leading to the evolution of cities.
• Harappans reached their “urban peak” or the ‘Mature Phase’ between 2600 and 1,900 bc.

How did the decline start?

• The downfall of civilisation starts with the de-urbanisation phase.
• De-urbanisation was due to a decrease in temperature and a decline in summer monsoon rainfall in the region.
• The trigger for the urban Harappan collapse was thus due to the decline of the summer monsoon.
• This period also saw an increase in winter monsoon.
• This also reduced the flow of the Indus River and its tributaries which led to migration of the people further east towards Ganga.
• This triggered the metamorphosis of the urban Harappan civilisation into a rural society and further expansion to east.
• The winter monsoon also weakened between 1300bc-1000bc.
• This could have played a major role in the demise of the rural late Harappans also and the end of one of greatest civilisation.