Skip to comments.Indus cities dried up with monsoon
Posted on 05/02/2006 7:20:20 AM PDT by SunkenCiv
The earliest settlement in the subcontinent with evidence of agriculture and domestication at Mehrgarh now in Pakistan is about 9,000 years old. This coincides with the peak intensification of the monsoon, the study said... The Arabian Sea sediments and other geological studies show that the monsoon began to weaken about 5,000 years ago. The dry spell, lasting several hundred years, might have led people to abandon the Indus cities and move eastward into the Gangetic plain, which has been an area of higher rainfall than the northwestern part of the subcontinent... About 1,700 years ago, the monsoon began to improve again, leading to increased farm produce for several centuries and contributing to the relative prosperity in India during the medieval ages, from AD 700 to 1200. After a weak phase between AD 1400 and 1800, the monsoon has again strengthened over the past 200 years, leading to increasing productivity. Scientists, however, believe that global warming might now be influencing the monsoon.
(Excerpt) Read more at telegraphindia.com ...
I wonder if the warmer sea surface temps are found in the computer simulation, or actually found in the world? See also The Little Ice Age: How Climate Made History 1300-1850 by Brian M. Fagan, for some accounts of recent monsoon failures in India (one resulted in the disastrous Moslem invasion of India).MJO Key To Monsoon Climate PredictionsA NASA researcher says warmer or colder sea surface temperatures affect the Madden Julian Oscillation, a large-scale atmospheric circulation that regulates rainfall associated with South Asian and Australian monsoons. Monsoon winds change direction with the seasons and develop from changing patterns of atmospheric circulation caused by changes in heating and cooling of land and oceans. The summer monsoon blows southwesterly across the Indian Ocean and is very wet, but in July there usually is a break when the rains stop and re-start. MJO affects that break but MJO also in turn is affected by changes in sea surface temperatures. Man Li Wu, a researcher from NASA's Goddard Space Flight Center, used computer models to simulate the atmosphere in the region. She noted warmer sea surface temperatures usually are found five to 10 days before the strengthening of the precipitation on the MJO time scale. Changes in sea surface temperatures may be responsible for up to 30 percent of MJO strength fluctuations.
by Robert Gutro
2002Himalayas Impact Global Climate, Study FindsUsing geologic records and a computer-driven climate model, the portrait shows the rise of the towering Himalayas and the adjacent Tibetan Plateau, the world's largest, as the primary driver of the onset of Asian monsoons about 8 million years ago, and hints that the rise of the world's tallest mountains and plateau may also have helped set the stage for the Ice Ages that began about 2.5 million years ago... To assess the effects of the rise of the Himalayas and the Tibetan Plateau on climate, the team used a computer model of world climate to show that the mountain and plateau uplift enhanced both the winter and summer Asian monsoons and gave rise to a drying trend in central Asia... The Chinese loess deposits, together with the records from Indian Ocean sediments that indicate onset of the Indian summer monsoon at about the same time, provide physical evidence that is consistent with the computer model's picture of the evolution of Asia's climate.
National Geographic Society
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speaking of the monsoon:
INTAMM | 1997 | Xavier S. Thani Nayagam
Posted on 09/11/2004 11:07:01 PM EDT by SunkenCiv
The Voyage around the Erythraean Sea
Silk Road | 2004 | William H. Schoff
Posted on 09/12/2004 10:55:44 PM EDT by SunkenCiv
Pot sherd from Harappa
Stamp seal depicting a rhinoceros from Mohenjo-daro
The people of the Indus Valley Civilization also developed a writing system which was used for several hundred years. However, unlike some other ancient civilizations, we are still unable to read the words that they wrote.
Very nice posts by both of you. When I was first learning about the Indus Vally culture in the 1950's, the primary conjecture for the demise was deforestation because of the need for firewood. The people would have had to move to places with trees, and the area would have become desertified. Which came first, the chicken or the egg?
I used to tell this to a teacher of mine, back in school, 'If the egg came first, who incubated it???'.
I've read that an earthquake or two probably caused the now-dried Saraswati river to either change course, or disappear completely. What of that theory?
I must say, as an Indian, the Indian education system stresses very little on the Indus Valley Civilisation. The history of the country may be tiringly long, but this area gets a fraction of the attention it really deserves.
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