Ruins. Scientists have reconstructed the past climate for the region around Cantona, a large fortified city in highland Mexico, and found the population drastically declined in the past, at least in part because of climate change.

Scientists have reconstructed the past climate for the region around Cantona, a large fortified city in highland Mexico, and found the population drastically declined in the past, at least in part because of climate change.

The research appears in the online edition of the Proceedings of the National Academy of Sciences for the week of Jan. 26.

Lawrence Livermore researcher Susan Zimmerman and colleagues analyzed pollen, stable isotopes and elemental concentrations, which serve as proxies of past climatic and environmental conditions from lake sediments in the region and found evidence of a regional drought between 500 and 1150 AD, about the same time Cantona was abandoned.

Using Lawrence Livermore’s Center for Accelerator Mass Spectrometry, the team — consisting of from the University of California, Berkeley; Universidad Nacional Autonóma de Mexico; and the GFZ German Research Center for Geosciences — dated terrestrial organic material from 12-meter long sediment cores from the lake to establish the age control for this study. Radiocarbon dating and an age model showed that the centennial-scale arid interval between 500 and 1150 was overlaid on a long-term drying trend. The cores cover the last 6,200 years; however, the team focused on the last 3,800 years.

"We found that Cantona’s population grew in the initial phases of the drought, but by 1050 AD long-term environmental stress (the drought) contributed to the city’s abandonment," Zimmerman and colleagues said. "Our research highlights the interplay of environmental and political factors in past human responses to climate change."

Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants. It is in a semiarid basin east of Mexico City.

The team conducted a sub centennial reconstruction of regional climate by taking sediment samples from a nearby crater lake, Aljojuca. The modern climate of the region suggests that proxy data from the sediments record changes in summer monsoonal (May through October) precipitation.

"Our results suggest that climate change played a contributing role in the site’s history," Zimmerman said.

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If anyone is interested I have two articles on Dropbox that covers this hypothesis already based on other ecological work done in Mexico.

https://www.dropbox.com/s/69gez9qn1ieiuzq/BeekmanChristensen03JAMT.pdf?dl=0

https://www.dropbox.com/s/4exmhot5ow3caci/BeekmanChristensen11ChapMigration.pdf?dl=0

At Newly Discovered Water Temple, Maya Offered Sacrifices to End Drought

Nestled in a quiet forest in Belize, a deep aquamarine pool holds ruins from a time when the ancient Maya turned to a “drought cult,” archaeologists suggest, and hurried sacrifices to a water god to try to stave off the fall of their civilization.

At the Cara Blanca site in Belize, archaeologists report the discovery of a water temple complex: a small plaza holding the collapsed remnants of a lodge and two smaller structures. The main structure rests beside a deep pool where pilgrims offered sacrifices to the Maya water god, and perhaps also to the demons of the underworld.

The find paints a picture of drought-stricken devotion during the collapse of the Maya. The pyramid-building civilization thrived across Central America for centuries, only to see most of its cities collapse after A.D. 800. Read more.

Belize's Famous 'Blue Hole' Reveal Clues to the Maya's Demise

SAN FRANCISCO — The ancient Mayan civilization collapsed due to a century-long drought, new research suggests.

Minerals taken from Belize’s famous underwater cave, known as the Blue Hole, as well as lagoons nearby, show that an extreme drought occurred between A.D. 800 and A.D. 900, right when the Mayan civilization disintegrated. After the rains returned, the Mayans moved north — but they disappeared again a few centuries later, and that disappearance occurred at the same time as another dry spell, the sediments reveal.

Although the findings aren’t the first to tie a drought to the Mayan culture’s demise, the new results strengthen the case that dry periods were indeed the culprit. That’s because the data come from several spots in a region central to the Mayan heartland, said study co-author André Droxler, an Earth scientist at Rice University. Read more.

Alarming NASA photos show how California is shrinking

Scientists from United States and Germany discovered that from pictures obtained by the Gravity Recovery and Climate Experiment (GRACE) mission, two satellites that have been in orbit around the Earth since 2002. 

The pictures show three major moments in the seemingly never-ending drought. The leftmost photo is from June 2002, soon after GRACE’s launch. The middle image dates from June 2008, while the one on the right was taken in June 2014.

The colors show how much groundwater the West Coast has lost over time. 

And it’s messing with the gravity | Follow micdotcom 

NASA: California Needs 11 Trillion Gallons of Water to End Drought | NBC

Eleven trillion gallons — that’s the amount of water that NASA scientists say would be needed to replenish key California river basins in what they’re calling the first-ever estimate of the water necessary to end an episode of drought. That 11 trillion gallons is the deficit in normal seasonal levels that NASA said a team found earlier this year in the Sacramento and San Joaquin river basins, using Gravity Recovery and Climate Experiment (GRACE) satellites. The GRACE data, presented Tuesday at the American Geophysical Union meeting in San Francisco, showed those river basins losing about 4 trillion gallons per year — more than state residents use annually, NASA said.

In another finding, NASA said airborne measuring indicates the Sierra Nevada range snowpack was half previous estimates. “The 2014 snowpack was one of the three lowest on record and the worst since 1977, when California’s population was half what it is now,” Airborne Snow Observatory principal investigator Tom Painter of the Jet Propulsion Laboratory said in the NASA release.

California has been blasted by autumn storms dumping inches of much-needed rain - but that’s still not enough to get the Golden State out of its drought. “Recent rains are no reason to let up on our conservation efforts,” Felicia Marcus, chair of the State Water Resources Control Board, said recently.