I was not going to post this, but the Swiss reference has prompted me to make note of the recently published US data. It seems like a number of folks are using the difficult-to-interpret speleothem data to ride the Mayan prophecy craze to brief notoriety.
I have been happily wearing my Convention Mayacon 2012 shirt the last two days. Cave data suggests that climate shifts help explain Mayan prosperity and decline Classic Maya civilization rose and fell with the rains. This once-majestic society, known for massive pyramids and hieroglyphic writing, expanded during an unusually rainy time and declined as the sky’s spigots dried up and periodic droughts arrived, a new study suggests. A 2,000-year climate record, gleaned from a stalagmite inside a Belize cave, highlights a central role for climate shifts in the ancient civilization’s fortunes, say anthropologist Douglas Kennett of Penn State University and his colleagues. http://www.sciencenews.org/view/generic/id/346350/description/An_ancient_civilizations_wet_ascent,_dry_demise Reference to the actual paper: D.J. Kennett et al. Development and disintegration of Maya political systems in response to climate change. Science, Vol. 338, November 9, 2012, p. 788. doi:10.1126/science.1226299. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Because of the cave interest and the end of Life As We Know It, I bounced this around with Low Gun and a few others last week. It's not a new idea, but it sounds like some reasonably hard data backing up the idea. Whether or not this is "The Cause" or just another significant stressor on Mayan Society is another thing. The article also, justifiably, raises the question as to how much of the Mayan Territory was really affected by this drought event. Referance: Richardson Gill: The Great Mayan Droughts: Water, Life, and Death (University of New Mexico Press 2000). Now translated into Spanish and published in Mexico. He has also made a TV documentary about this by the BBC and the Learning Channel. (Ancient Apocalypse: The Mayan Collapse). Additionally, Bill MIxon rightly points out that this speleothem data is no slam dunk. This is data from one spot in one cave and even though it appears to coincide with other climatic suggestions, the headlines seem a bit overblown. It is likely that major climatic shifts are reflected broadly by the drips in a wet cave, but Bill points out that the flow of water to one drip in a cave follows a pretty complex route. I tend to agree with Bill in his caution about inferring surface climate from speleothem data, especially when it is from one speleothem in one cave by the same scientific team. It may be that enough different pieces of data from different teams is starting to paint a consensus picture. DirtDoc
