Civilisation Brought Down by Climate Change

The Indus or Harappan civilization. This culture once extended over more than 1 million square kilometres from the Arabian Sea to the Ganges – at its peak accounting for 10% of the world population. Developing some 5,200 years ago, the culture slowly disintegrated some 3 to 4,000 years ago, migrating toward the east.

This, the world’s earliest urban civilization in an area now covered by India, Pakistan, Nepal and Bangladesh appears to have been brought down by climate change, according to researchers. This vast Indus civilization was completely forgotten until the 1920s, and there are still many things we don’t know about them.

It was around 100 years ago that archaeologists began finding many instances of Harappan settlement remains along the Indus River and in a vast desert region bordering India and Pakistan – proof found that sophisticated cities had existed, with sea links to Mesopotamia, arts and crafts, and writing that is still undeciphered.

Cities were ordered into grids – exquisite plumbing not seen again until the Roman empire established itself – in what appeared to be a much more democratic society than Mesopotamia and Egypt, without large structures built in honour of kings. Harrapan people were so-called after one of their largest cities, and lived next to rivers, in the main

Speculation had been rife  about the links between this mysterious ancient culture and its rivers, the landscape of the where this long-forgotten civilization developed now reconstructed, shedding light on what happened, the research pointing to one of the clearest examples of climate change causing the collapse of a civilization.

The researchers collected data on geological history, having analyzed satellite data of the landscape and influenced collected samples of sediment to determine origins and ages and develop a time-line of landscape changes. The Harappan heartland got water from a glacier-fed Himalayan river – the Sarasvati, sacred river of Hindu mythology – which previous studies suggest may actually have been the Ghaggar, an intermittent river flowing only during strong monsoons.

Archaeological evidence suggested the river was home to intensive settlement during Harappan times. In the beginning, this monsoon-drenched river was prone to devastating floods, but over time, monsoons weakened, so agriculture and civilization flourished for nearly 2,000 years.

As solar energy in the region varied over several thousand years, less rain got into the regions affected by monsoons, and eventually, these monsoon-based rivers held too little water and dried, forcing the enterprising Harappans to flee east toward the Ganges basin, in pursuit of the reliable monsoon rains.

This change was undoubtedly disastrous for Indus cities, which collapsed, though smaller agricultural communities flourished, though urban arts like writing faded away.  How monsoons will react to modern climate change remains uncertain, but what climate change caused once before in the Indian sub-continent could quite easily be repeated again elsewhere.