FYI.

This story is over 5 years old.

Tech

Climate Change-Induced Drought Caused the Mayan Collapse

The collapse of the Mayan empire has already caused plenty of consternation for scientists and average Joes alike, and we haven't even made it a quarter of the way through 2012 yet. But here's something to add a little more fuel to the fire: A new...

The collapse of the Mayan empire has already caused plenty of consternation for scientists and average Joes alike, and we haven’t even made it a quarter of the way through 2012 yet. But here’s something to add a little more fuel to the fire: A new study suggests that climate change killed off the Mayans.

That’s been posited for some time, but this report adds the twist that the change in question amounted to about a 40 percent drop in rainfall. Researchers argue that, if that’s indeed what set up the final blow, the Mayans succumbed to climate change that was much less severe than previously expected.

Advertisement

The paper, published today in Science by Martín Medina-Elizalde and Eelco Rohling of the University of Southampton, explains that the Mayan civilization collapsed over a period between 800-1000 C.E., known as the Terminal Classic Period (TCP). The authors are quick to note that climate change isn’t the only factor in the Mayan collapse, but it likely played a role. They write:

Despite evidence suggesting that climate change does not fully explain the complex geographic and sociopolitical events of the TCP, paleoclimate records and archaeological evidence suggest that the TCP was punctuated by a series of drought events that probably triggered significant societal disruptions at this time.

The issue with prior studies was that they didn’t normalize various sets of paleoclimate records, meaning that it was impossible to draw firm conclusions that fit all data. Medina-Elizalde and Rohling used four well-resolved records from the Yucatan Peninsula, one based off of stalagmite growth in a cave, two based off of biological matter in a pair of lakes, and one from the sediment record of one of those lakes.

The Yucatan Peninsula Lake (Credit: Science/AAAS)

“We now how independent evidence from two very different paleoclimate archives (stalagmites and lake fossils) that suggest the same climate pattern and confirm the magnitude of changes in precipitation,” Medina-Elizalde told me via email. “These records suggest that the Maya civilization did not experience only one drought but a series of eight droughts related to reductions in rainfall between 25 and 40%, relative to the period when the civilization flourished.”

The pair found that, while there were indeed "considerable reductions" in precipitation during the TCP, but they weren’t as severe as prior models had suggested. The authors also found evidence that the drop in rainfall was due to a lack of tropical storms, which they said are crucial for maintaining the water table in the Yucatan.

Advertisement

The Yucatan is apparently highly sensitive to water reductions, a hypothesis supported by current data, and that means that reduced tropical storm action was likely enough to trigger the downfall of the Mayans, thanks to a quickly-depleting water supply. It’s important to note that a couple centuries’ worth of drought didn’t cause the Mayan collapse on its own. The social, cultural, and political responses to the drought would likely have delivered the crushing blow.

“What can you do if from one year to the other you don’t have enough freshwater to sustain 30% of your population and there is nowhere to run?” Medina-Elizalde said. “The carrying capacity of the entire Yucatan Peninsula was not able to support a very large proportion of the total population. Climate was not [the only factor]. As our study suggests, the TCP rainfall reductions where not of catastrophic proportions, as it has been speculated, but they were strong enough and persistent enough (eight droughts during the TCP with durations between 6 and 18 years), to trigger severe societal responses. The TCP was distinctive because it was marked by a severe increase in warfare among city-states.”

Of course, the big question to our naturally self-absorbed selves is whether or not the Mayan scenario will happen again. Luckily, it’s doubtful to occur in 2012, but Medina-Elizalde and Rohling note that current trends suggest that there will be a similar decrease in Yucatan precipitation by the end of this century. So another drought disaster in Mayan country, and perhaps elsewhere in Mexico and Central America, is certainly possible.

Advertisement
The temple in the Kingdom of Tikal (Credit: Science/AAAS)

“If emissions of greenhouse gases continue rising, then there is a high probability that the Yucatan Peninsula and other regions with similar rainfall deficits, will experience similar climate changes (perhaps for different reasons) by the end of this century, as the last IPCC reports suggest,” Medina-Elizalde said.

It’s hard to ignore that, at the end of the day, water is likely our most precious resource — that is, until we start hearing about oxygen deficits. One of the least predictable aspects of climate change is how it will affect global inclement weather patterns, which, as in the case of the Mayan’s lack of cyclones, can be a huge problem. The key is how we’ll respond to those changes.

“Let’s imagine that from one year to another cities can no longer supply freshwater and the agricultural goods to support around one-third of the population,” Medina-Elizalde said. “Then we can all speculate as to what would happen, and I am sure that we would all come up with different scenarios. I think that ultimately, human responses to climate change will depend on how mature, efficient, organized and honest our sociopolitical institutions are, and ultimately, how mature we all are.”

It’s impossible to tell what might happen to a culture when the tap starts to run dry, although a smart bettor would put money on trouble. And it’s not like it hasn’t happened since: the California Water Wars really happened, and their specter won’t be going away any time soon.

Follow Derek Mead on Twitter.

Connections: