Wednesday, December 12, 2012

Climate and Collapse

Climate matters:
“Every one of these Maya monuments is political history,” says linguist Martha Macri, a professor of Native American studies at UC Davis.

Inscribed on each monument is the date it was erected and dates of significant events, such as a ruler’s birthday or accession to power, as well as dates of some deaths, burials and major battles. The researchers noted that the number of monuments carved decreased in the years leading to the collapse.

“Unusually high amounts of rainfall favored an increase in food production and an explosion in the population between AD 450 and 660,” says Douglas Kennett, lead author and professor of anthropology at Penn State.

“This led to the proliferation of cities like Tikal, Copan, and Caracol across the Maya lowlands. The new climate data show that this salubrious period was followed by a general drying trend lasting four centuries that was punctuated by a series of major droughts that triggered a decline in agricultural productivity and contributed to societal fragmentation and political collapse.

“The most severe drought (AD 1020 and 1100) in the record occurs after the widespread collapse of Maya state centers (referred to as the Maya collapse) and may be associated with widespread population decline in the region.”

Over the centuries, according to Kennett, the cities suffered a decline in their populations and Maya kings lost their power and influence.

“The linkage between an extended 16th century drought, crop failures, death, famine, and migration in Mexico provides a historic analog, supported by the cave stalagmite samples, for the socio-political tragedy and human suffering experienced periodically by the Classic Period Maya,” he says.

“Here you had an amazing state-level society that had created calendars, magnificent architecture, works of art, and was engaged in trade throughout Central America,” says University of California, Davis, anthropology professor and co-author Bruce Winterhalder. “They were incredible craftspersons, proficient in agriculture, statesmanship, and warfare—and within about 80 years, it fell completely apart.”

The rich archaeological and historical records of the Maya provide an opportunity to examine the long-term effects of climate change for both the development and disintegration of complex sociopolitical systems like our own, notes Kennett, an expert on the human effects of global climate change and the environmental impacts of expanding populations.

“The effects of climate change are complex and play out over multiple time scales,” he says. “Abrupt climate change is only part of the story. In addition to climate drying and drought, the preceding conditions stimulating societal complexity and population expansion helped set the stage for later stress on their societies and the fragmentation of political institutions.”

“It has long been suspected that weather events can cause a lot of political unrest and subject societies to disease and invasion,” Macri says. “But now it’s clear. There is physical evidence that correlates right along with it. We are dependent on climatological events that are beyond our control.”

Winterhalder says: “It’s a cautionary tale about how fragile our political structure might be. Are we in danger 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.” (

For point of reference, see Thinking About Yields Under Future Drought (Early Warning).

For an overview of Maya technology, see this book: The Lost Secrets of Maya Technology.
The Lost Secrets of Maya Technology is an exciting documentation of O’Kon’s exploration, research, forensic engineering and virtual reconstruction of lost technological achievements that enabled the Maya to construct cities towering above the rainforest, water systems with underground reservoirs, miles of paved jungle tracks, and the longest bridge in the ancient world.

He also explains how Maya engineers built multi-story buildings that were not exceeded in height until the first skyscraper erected in the U.S. in 1885, how they invented the blast furnace 2,000 years before it was patented in England, and developed the vulcanization of rubber more than 2,600 years before Goodyear.
There's a podcast with the author, James O'Kon on Disinfo here. Not the best speaker and a bit doddering, but still maybe worth a listen. The Mayans are a lesson in using technology appropriate to place and resources. As the author points out, one reason they didn't use iron is because they used jadite for many of the same purposes, which has several advantages over metals. As I recall, obsidian was used similarly, including for weapons; a benefit as obsidian does not rust in the jungle humidity. The same goes for bone over metal armor. And the wheel does not make much sense in a dense jungle with dirt roads and no pack or draught animals. If your main cargo "animal" is a bipedal human, the Mayan technology makes more sense- backpacks and sledges.

And in the Old World:
Beginning about 3500 B.C., the Sumerian culture flourished in ancient Mesopotamia, which was located in present-day Iraq. Ancient Sumerians invented cuneiform writing, built the world's first wheel and arch, and wrote the first epic poem, "Gilgamesh." But after 200 to 300 years of upheaval, the Sumerian culture disappeared around 4,000 years ago, and the Sumerian language went extinct soon after that.

Konfirst wanted to see if a drought that spanned about 200 years may have caused the decline. Several geological records point to a long period of drier weather in the Middle East around 4,200 years ago, Konfirst said. The Red Sea and the Dead Sea had increased evaporation; water levels dropped at Lake Van in Turkey, and cores from marine sediments around that period indicate increased dust in the environment.

"As we go into the 4,200-year-ago climate anomaly, we actually see that estimated rainfall decreases substantially in this region and the number of sites that are populated at this time period reduce substantially," he said. Around the same time, 74 percent of the ancient Mesopotamian settlements were abandoned, according to a 2006 study of an archaeological site called Tell Leilan in Syria. The populated area also shrank by 93 percent, he said. "People still live in this region. It's not that the collapse of a civilization means that an area is completely abandoned," he said. "But that there's a sharp change in the population."

During the great drought, two waves of marauding nomads descended upon the region, sacking the capital city of Ur. After around 2000 B.C., ancient Sumerian gradually died off as a spoken language in the region. For the next 2,000 years, the tongue lingered on as a dead written language, similar to Latin in the Middle Ages, but has been completely extinct since then, Konfirst said. The coincidence of the social upheaval, depopulation in the area and the geologic record of drought suggests climate change might have played a role in the loss of the Sumerian language, Konfirst said. The findings also suggest that modern-day civilizations may be vulnerable to climate change, he said.
Drought May Have Killed Sumerian Language (Live Science)


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