Tuesday, December 18, 2012

Mayan doomsday: Civilization collapse linked to climate change

Mayan doomsday
Mayan civilization collapse and climate change
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Comalcalco was a major Mayan port city that was believed to have flourished between A.D 700 to A.D 900. Though others place it much older, and even perhaps older still, since the finds at Nakbe in the Petén, it may go back to 1000 BCE, and beyond. Since there was no rock quarry or stone to use in the area, they built the buildings out of bricks made of baked mud. The Maya raised HUGE structures made out of these bricks. That in itself makes this place unique to all the other Mayan locations. But, you see, the bricks have inscriptions on them.
The map of the Mayan Zone
Mayan ruins in Guatemala
 Where the rain forests of Guatemala now stand, a great civilization once flourished. The people of Mayan society built vast cities, ornate temples, and towering pyramids. At its peak around 900 A.D., the population numbered 500 people per square mile in rural areas, and more than 2,000 people per square mile in the cities -- comparable to modern Los Angeles County. 

This vibrant "Classic Period" of Mayan civilization thrived for six centuries. Then, for some reason, it collapsed.

The fall of the Maya has long been one of the great mysteries of the ancient world. 

The Rise and Fall of the Mayan Empire:
Sever, NASA's only archeologist, has been using satellites to examine Mayan ruins. Combining those data with conventional down-in-the-dirt archeological findings, Sever and others have managed to piece together much of what happene
From pollen trapped in ancient layers of lake sediment, scientists have learned that around 1,200 years ago, just before the civilization's collapse, tree pollen disappeared almost completely and was replaced by the pollen of weeds. In other words, the region became almost completely deforested.
 Without trees, erosion would have worsened, carrying away fertile topsoil. The changing groundcover would have boosted the temperature of the region by as much as 6 degrees, according to computer simulations by NASA climate scientist Bob Oglesby, a colleague of Sever at the MSFC. Those warmer temperatures would have dried out the land, making it even less suitable for raising crops.
Figure of a Maya priest.

Rising temperatures would have also disrupted rainfall patterns, says Oglesby. During the dry season in the Petén, water is scarce, and the groundwater is too deep (500+ feet) to tap with wells. Dying of thirst is a real threat. The Maya must have relied on rainwater saved in reservoirs to survive, so a disruption in rainfall could have had terrible consequences.
(Changes in cloud formation and rainfall are occurring over deforested parts of Central America today, studies show. Is history repeating itself?)
Using classic archeology techniques, researchers find that human bones from the last decades before the civilization's collapse show signs of severe malnutrition.
"Archeologists used to argue about whether the downfall of the Maya was due to drought or warfare or disease, or a number of other possibilities such as political instability," Sever says. "Now we think that all these things played a role, but that they were only symptoms. The root cause was a chronic food and water shortage, due to some combination of natural drought and deforestation by humans."
Throne 1 of Piedras Negras
A message from 900 A.D.: it's never too late to learn from your ancestors:
Using oxygen isotope dating on stalagmites taken from caves near various Mayan sites, scientists were able to determine precipitation levels in the area, and correlate these with known political records taken from Mayan stele and hieroglyphics.
They found, quoting materials supplied by UC Davis:
Periods of high and increasing rainfall coincided with a rise in population and political centers between A.D. 300 and 660. A climate reversal and drying trend between A.D. 660 and 1000 triggered political competition, increased warfare, overall sociopolitical instability, and finally, political collapse. This was followed by an extended drought between A.D. 1020 and 1100 that likely corresponded with crop failures, death, famine, migration and, ultimately, the collapse of the Maya population.
Temple of the Cross at Palenque; there is an intricate roof comb and corbeled arch

 Commenting on the finds from Central America, Bruce Winterhalder, from UC Davis' Native American Studies, bridges the centuries: "It's a cautionary tale about how fragile our political structure might be. Are we in danger in the same way the Classic Maya were in danger? I don't know. But I suspect that just before their rapid descent and disappearance, Maya political elites were quite confident about their achievements."

*Note: all pictures thankfully shared from various sources..

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