Indus valley civilization collapse, climate change and threats of global warming

# Science in the news

200 year long drought wiped out the Indus valley  

In a ground-breaking discovery led by an Indian-origin palaeoclimatologist  
(http://www.esc.cam.ac.uk/people/research-students/yama-dixit)

researchers have found that a 200-year-long monster drought nearly 4,200 years ago 

doomed the Indus Valley Civilization in present Pakistan and northwest India.

Gateway at harappa: Indus Valley civilization
Pics courtesy:http://www.crystalinks.com/induscivilization.html

"The Indus Valley was characterised by large, well-planned cities with advanced municipal sanitation systems and a script that has never been deciphered.

Indus Valley Seals
Pic courtesy:http://www.crystalinks.com/induscivilization.html

pic courtesy:http://gatescambridge.org/

our-scholars/Profile.aspx?

ScholarID=5469

But the Harappans seemed to slowly lose their urban cohesion, and their cities were gradually abandoned,' explained Yama Dixit, a palaeoclimatologist at University of Cambridge.(http://www.deccanherald.com/content/389730/200-year-long-drought-wiped.html)

Palaeoclimatological research

The team assigned ages to sediment layers using radiocarbon dating of organic matter.

In various layers, they collected the preserved shells of tiny lake snails which are made of a form of calcium carbonate called aragonite.

The team also looked at the oxygen in the argonite molecules, counting the ratio of the rare oxygen-18 isotope to the more prevalent oxygen-16.

During drought, oxygen-16, which is lighter than oxygen-18, evaporates faster so that the remaining water in the lake and, consequently, the snails' shells, become enriched with oxygen-18.

The team's reconstruction showed a spike in the relative amount of oxygen-18 between 4,200 and 4,000 years ago.

The data, published in the journal Geology1, suggests that the regular summer monsoons stopped for some 200 years.

According to Anil Gupta, director of the Wadia Institute of Himalayan Geology in Dehradun, this work fills a gap in the geographic record of ancient drought. (http://www.deccanherald.com/content/389730/200-year-long-drought-wiped.html)  

Reference link and abstract of Yama Dixit's research paper:

http://www.esc.cam.ac.uk/people/research-students/yama-dixit

The Bronze Age Harappan Civilization was one of the world’s earliest great urban civilizations and flourished from ~4600 BP to 3900 BP. The collapse of its integrated urban structure has prompted much speculation, including suggestions of climate and environmental change playing a role in their demise. Palaeoclimate proxy evidence indicates that the time of the Harappan Civilization was marked by variable monsoon strength, punctuated by episodes of aridity. A decrease in the strength of the South Asian monsoon at 4.2 ka BP has been linked by some to the termination of the urban phase of the Harappan Civilization. However, the link between climate change and Indus cultural transformation is equivocal, particularly because of a lack of well-dated paleoclimate records from the region occupied by the Indus Civilization.

For my PhD, I am reconstructing the Holocene palaeoclimate history using lacustrine sediments from three lakes lying across the precipitation gradient on the plains of NW India. This study will contribute to our understanding of the Holocene history of past environmental and climatic change in this region and assess possible climate-cultural connections.

I am funded by Gates Cambridge Trust and my PhD research is supervised by Prof. David Hodell.

Concern of the day

Climate impacts 'overwhelming' - UN

thankfully shared from a report by Matt McGrath for BBC    

http://www.bbc.com/news/science-environment-26810559?OCID=fbasia&ocid=socialflow_facebook

The impacts of global warming are likely to be "severe, pervasive and irreversible", a major report by the UN has warned.

"Nobody on this planet is going to be untouched by the impacts of climate change,'' IPCC chairman Rajendra Pachauri told journalists at a news conference in Yokohama.

"Now, ignorance is no longer a good excuse," Michel Jarraud, secretary-general of the World Meteorological Organization has said.

 

A kind of warning for Indian subcontinent !!

We may lose much more, if lesson not learn on time

Our greedy developmental desires have set a rapid rate of deforestation, hills are broken for granite and sand, pollution is already growing at steady speed. In addition to that India doesn't get polar streams due to high altitude tibetan plateu. Entire country depends on monsoon only. Are we moving towards a scary future for our coming generations due to climate change. We are at jet speed spoiling the nature and natural resources...What is the value of the money..when the land turns into Mars like. (rajk12345/http://www.deccanherald.com/content/389730/200-year-long-drought-wiped.html)

Saraswati by Raja Ravi Varma 

pic courtesy:http://en.wikipedia.org/wiki/Saraswati

Losing ground water resource could be deavastating

Like all rivers, it was fed from a glacier which went dry. Example Gangotri Glacier now has receded some 8Km all the way to GoMukh. 100yrs back Gangotri glacier was near where today Gangotri is. Also , Indus valley civlization and the word Harappa are modern concoted.

Its aptly called as Sarswati civilization. So what caused the glacier to melt down could the global warming (1) with deforestation due to war (Kurukshetra war which occured some 5134 yrs ago, from history we know after the war river Sarswati ran for some 800 yrs +) that took place in the vicinity. (Dr. B. M. Nandeeshaiah/http://www.deccanherald.com/content/389730/200-year-long-drought-wiped.html)