Science Cafe explores link from climate to collapse of civilizations
The third Berry College Science Cafe dealt with how climate change has led to the collapse of past civilizations, and how scientists like Zachary Taylor, assistant professor of environmental science, reconstruct past climates to provide clues into what may have happened.
“It’s kind of like pulling a slot machine. If certain factors affecting climate all line up at a certain time, a destabilization of a civilization could occur,” Taylor said. However, human activities contributing to an expansion of the greenhouse effect — “warming that results when the atmosphere traps heat radiating from Earth toward space,” according to a NASA report — is like “stacking the deck,” he said.
“It’s usually not just one thing,” Taylor said.
Prior to addressing the collapse of the Mayan civilization in southern Mexico and Northern Guatemala, Taylor touched on a few examples from history related to climate change. The image of a Victorian Christmas given to us by author Charles Dickens and his famous work “A Christmas Carol” is due to a period of changing climate giving rise to colder weather and snow in England during the early 1840s.
In trying to determine past climates, scientists can study tree rings and sediment to find clues.
Tree rings can show off years of little growth, with rings being closer together, offering insight into periods of dryness and high temperatures.
Sediment cores — which Taylor once traveled to Colorado to retrieve from a mountain lake after floating down river in a Huckleberry Finn raft — are like “time capsules” to changes in environment and climate, he said. Clues can be revealed from the type of organic content in the sample, if carbon is present — is it fine or coarse and does it have fossilized pollen grains which gives an idea of what vegetation was growing at that time.
The Mayans built infrastructure into the layout of their towns to collect water in a reservoir system, using sand to filter water.
“If you were going to put this much effort into it clearly water was a concern of theirs,” Taylor said.
The Intertropical Convergence Zone — a low pressure area with very hot air produces high levels of condensation and rainfall — migrating north would bring rainy periods to the Mayans in the summer.
These dry periods can be connected to the collapse of the Mayan civilization and the abandonment of sites and violence. It was not a good time to be a ruler who is promising rain will come during a drought, Taylor said.
The effect of climate change on the destruction of civilizations can be seen throughout history around the world, including more recently in a drought in Syria in 1998 which was probably the worst in 500 years, Taylor said, and was two to three times more likely to happen due to human activities. This natural event — leading to migration from farms to cities — along with a number of other issues put strain on Syrian society and producing unrest degenerating into complete civil war since 2011.