After flourishing from 2600 – 1900 B.C.E, the Indus Valley Civilization entered a period of decline. The various reasons cited for the decline include climate change, like the decline of monsoons. A crucial factor was also the disappearance of substantial portions of the Ghaggar Hakra river system, believed to be the mythical Saraswati.
Climate changes are sometimes responsible for the development of civilizations. For example, a pre-historic climate change in Eastern Sahara resulted in the rise of the Egyptian civilization. There is an argument that civilizations developed as a by-product of adaptation to climate change and hostile environments.
The early civilisations of Egypt, Mesopotamia, South Asia, China and northern South America were founded between 6000 and 4000 years ago when global climate changes, driven by natural fluctuations in the Earth’s orbit, caused a weakening of monsoon systems resulting in increasingly arid conditions. These first large urban, state-level societies emerged because diminishing resources forced previously transient people into close proximity in areas where water, pasture and productive land was still available.
“Civilisation did not arise as the result of a benign environment which allowed humanity to indulge a preference for living in complex, urban, ‘civilized’ societies,” said Dr. Brooks.
“On the contrary, what we tend to think of today as ‘civilisation’ was in large part an accidental by-product of unplanned adaptation to catastrophic climate change. Civilisation was a last resort – a means of organising society and food production and distribution, in the face of deteriorating environmental conditions.”
He added that for many, if not most people, the development of civilisation meant a harder life, less freedom, and more inequality. The transition to urban living meant that most people had to work harder in order to survive, and suffered increased exposure to communicable diseases. Health and nutrition are likely to have deteriorated rather than improved for many.
The new research challenges the widely held belief that the development of civilization was simply the result of a transition from harsh, unpredictable climatic conditions during the last ice age, to more benign and stable conditions at the beginning of the Holocene period some 10,000 years ago. [Climate change rocked cradles of civilization]