A climate change history class

Getting to professor Anindya Sarkar is a task After a twoday chase the head of department of Geology and Geophysics at IIT Kharagpur who has been busy with classes and meetings agrees to take us down the Indus Valley civilisation lane Contrary to our textbook knowledge that it was 5500 years old a recent report published in Naturersquos Scientific Reports a piece he collaborated on along with a team of researchers from IIT Kharagpur Institute of Archaeology Deccan college Pune Physical Research laboratory and Archaeological Survey of India ASI claims it is 8000 years oldbelow Cattle bone found at the above Bhirrana site PicASIA report like this creates hype But our findings must be established on a larger scale and extensive work is needed admits SarkarThree years ago the team discussed the excavation of Bhirrana site in Haryana by late Dr LS Rao in 2005 The site showed preservation of all cultural levels of this ancient civilisation from the PreHarappan Hakra phase through Early Mature Harappan to mature Harappan time Mohenjodaro and Harappa which are now in Pakistan were first excavated during the British rule Since the last 50 years the ASI excavations have found a large number of Indus valley settlements in West and North West India major cities like Lothal and Dholavera in Gujarat Kalibanga Rakhigadhi says Sarkar According to professor VS Shinde ViceChancellor Deccan college Rakhigari could have been larger than MohenjodaroBhirrana was part of a high concentration of settlements along the now dried up mythical Vedic river valley lsquoSaraswatirsquo an extension of Ghaggar River in the Thar DesertAnindya SarkarThe material found in the trench belonged to early middle and late cultural layers Some of the mature pottery in Bhirrana dates to 6000 years as seen through optically stimulated luminescence OSL says Sarkar adding that Dr Navin Juyal of Physical Research Laboratory Ahmedabad dated the pottery With this we knew there would be older materialhe addsThe settlers faced climate change too They coped well with it unlike our present situation says Sarkar posing us a question Why does a civilisation disappearThere are many hypotheses mdash flood famine or drought Dr Rao had found bones and teeth of animals like cows goats deer and antelopes that were studied by Dr Arati Deshpande Mukherjee assistant professor at Deccan College At IIT we analysed the oxygen isotope composition in the bone and tooth phosphates to unravel the climate pattern as it preserves the signature of ancient meteoric water and in turn the intensity of monsoonal rainfallPreHarappan humans started inhabiting this area along the GhaggarHakra rivers in a climate that was favourable for settlement The monsoon was much stronger from 9000 years to 7000 years says Sarkar adding that the agrarian civilisation started growing when there was plenty of rainfall The now seasonal GaggharHakra River was probably perennial flowing through the Thar desert and up to the Arabian sea The area was not as arid as it is today he says Though the monsoo got weaker the civilisation continued to evolve which shows the settlers had a way of coping with climate changeAdapting to climate change the settlers started growing drought resistant millets instead of wheat and barley which are waterintensive crops The yields of these crops are tend to be low and probably the large granaries of mature Indus cities could not be sustained anymore says Sarkar This led to the abandoning of the organised large storage system giving rise to individual householdbased crop processing and storage systems This in turn could have acted as catalyst for the deurbanisation of the Harappan civilisation Most people believe it was not an abrupt end Rather it disintegrated over periods and even migrated to as distant places as Himalayan the foothillsLessons to learnOne thing is established We have an ancient root and I say this without attributing to mythology or religion A scientist can tell only as much as his data permits him to he quips Another pertinent question is that with all our modern technology scientific knowledge will the present civilisation survive the next few centuries One thing is sure that these people with no modern technology survived for several thousand years We have pumped huge CO2 from fuel that nature stored for millions of years As a consequence we already have severe droughts and extreme climate events More than onethird of Indiarsquos districts are affected by severe drought It will be curious to know how long the modern human with all space communication and agrobio technology will survive the global climate change We have a challenge before us and Irsquom not sure how we will fare