Water and climate. With our planet changing due to global warming, water is a large part of many conversations and studies. Whether it’s too much (think of the flooding caused by hurricane Sandy) or not enough (this summer’s drought in the Midwest) or unhealthy water due to irrigation, fracking or other pollution, water is our most valuable resource—sustaining all life here on the planet.

This week, we’ll look at recent research on water and climate. Today we’ll start in the past, to understand how climate and water affected human life hundreds of years ago.

The collapse of the Maya is one of the world’s most enduring mysteries. But a recent study in the journal Science, combining a precise climatic record of the Maya environment with a precise record of Maya political history, may provide a better understanding of the role weather had in the civilization’s rise and fall.

And it all has to do with water—plentiful rainfall, followed by drought. The researchers studied the isotopes in 2,000 year-old stalagmite samples from a cave in Belize. Nature News describes the process:

The team estimated historical rainfall in the Mayan lowlands by measuring oxygen isotopes incorporated into the stalagmite from rainwater that seeped into the cave from the ground above. The precipitation levels were tied to specific dates by measuring the ratio of radioactive isotopes in the stalagmite.

“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 high amount of rainfall, he says, was followed “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 and may be associated with widespread population decline in the region.”

Social unrest is often tied to drought and food availability. If drought should persist because of global warming in the future, perhaps we can learn from the Maya, says co-author Bruce Winterhalder, of UC Davis. “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.”

Tomorrow: Are droughts overestimated?

Image: Douglas Kennett, Penn State

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