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Guatemala

Geosciences Column: How climate change put a damper on the Maya civilisation

Geosciences Column: How climate change put a damper on the Maya civilisation

More than 4,000 years ago, when the Great Pyramid of Giza and Stonehenge were being built, the Maya civilisation emerged in Central America. The indigenous group prospered for thousands of years until its fall in the 13th century (potentially due to severe drought). However, thousands of years before this collapse, severely soggy conditions lasting for many centuries likely inhibited the civilisation’s development, according to a recent study published in EGU’s open access journal Climate of the Past.

During their most productive era, often referred to as the Classic period (300-800 CE), Maya communities had established a complex civilisation, with a network of highly populated cities, large-scale infrastructure, a thriving agricultural system and an advanced understanding in mathematics and astronomy. However, in their early days, dating back to at least 2600 BCE, the Maya people were largely mobile hunter-gatherers, hunting, fishing and foraging across the lowlands.

Around 1000 BCE, some Maya communities had started to transition away from their nomadic lifestyles, and instead were moving towards establishing more sedentary societies, building small villages and relying more heavily on cultivating crops for their sustenance. However, experts suggest that agricultural practices didn’t gain momentum until 400 BCE, raising the question as to why Maya development was delayed for so many centuries.

By analysing two new palaeo-precipitation records, Kees Nooren, lead author of the study and a researcher at Utrecht University in the Netherlands, and his colleagues were able to gain insight into the environmental conditions during this pivotal time, and the impact that climate change could have had on the Maya society.

To determine the regional climate conditions during this period of time, the authors examined a beach ridge plain in the Mexican state of Tabasco, off the Gulf of Mexico, which contains a long-term record of ridge elevation changes for much of the late Holocene. Since precipitation has a large influence on the elevation of this beach ridge, this record is a good indicator of how much rainfall and flooding may have occurred during Maya settlement.

A large part of the central Maya lowlands (outlined with a black dashed line) is drained by the Usumacinta (Us.) River (a). During the Pre-Classic period this river was the main supplier of sand contributing to the formation of the extensive beach ridge plain at the Gulf of Mexico coast (b). Periods of low rainfall result in low river discharges and are associated with relatively elevated beach ridges. Taken from Nooren, K et al., 2018

Additionally, the researchers also assessed core samples taken from Lake Tuspan, a shallow body of water in northern Guatemala that is situated within the Central Maya Lowlands. Because the lake receives its water almost exclusively from a small section of the region (770 square kilometres), its sediment layers provide a good record of rainfall on a very local scale.

The image on p. 74 of the Dresden Codex depicts a torrential downpour probably associated with a destructive flood (Thompson, 1972). Taken from Nooren, K et al., 2018

The research team’s analysis suggested that, starting around 1000-850 BCE, the region shifted from a relatively dry climate, to a wetter environment. Such conditions would have made a farming in this region more difficult and less appealing compared to foraging and hunting. The researchers suggest that this change in climate could be one of the reasons why Maya agricultural development was at a standstill for such a long time.

The researchers also propose that this long-term climate trend could have been brought on by a shift of the Intertropical Convergence Zone (ITCZ), a region near the equator where northeast and southeast winds intermingle and where most of the Earth’s rain makes landfall. The position of this zone can move naturally in response to Earth’s changes in insolation, and a northerly shift of the ITCZ could help account for some of the morphological changes the authors observed in the precipitation records.

After more than 450 years of excessive rainfall and large floods, the records then suggest that the region experienced drier conditions once again. By this time period, the Maya populations began to rapidly intensify their farming efforts and develop major cities, further suggesting that the wet conditions may have helped delay such efforts.

This is not the first time the Nooren and his colleagues have found evidence of major environmental influence on the Maya civilisation. For example, earlier research led by Nooren suggests that, in the 6th century, the El Chichón volcano in southern Mexico released massive amounts of sulfur into the stratosphere, triggering global climate change that likely contributed to a ‘dark age’ in Maya history for several decades. During this time, often referred to as the “Maya Hiatus,’ Maya societies experienced stagnation, increased warfare and political unrest. The research results were presented at the 2016 General Assembly and later published in Geology.

The results of these studies highlight how changes in our climate have greatly influenced communities and at times even shaped the course of societal history, both for better and for worse.

By Olivia Trani, EGU Communications Officer

References

Ebert, C. et al.: Regional response to drought during the formation and decline of Preclassic Maya societies. Quaternary Science Reviews 173:211-235, 2017

Nooren, K., Hoek, W. Z., Dermody, B. J., Galop, D., Metcalfe, S., Islebe, G., and Middelkoop, H.: Climate impact on the development of Pre-Classic Maya civilization. Clim. Past, 14, 1253-1273, 2018

Nooren, K.: Holocene evolution of the Tabasco delta – Mexico : impact of climate, volcanism and humans. Utrecht University Repository (Dissertation). 2017

Nooren, K. et al.: Explosive eruption of El Chichón volcano (Mexico) disrupted 6th century Maya civilization and contributed to global cooling, Geology, 45, 175-178, 2016

Press conference: Volcanoes, climate changes and droughts: civilisational resilience and collapse. European Geosciences Union General Assembly 2016

Caltech Climate Dynamics Group, Why does the ITCZ shift and how? 2016

Studying an active volcano – in pictures

Studying an active volcano – in pictures

Santiaguito volcano in Guatemala is one of the most active volcanoes in Central America: currently erupting every 45-90 mintues, from its active lava dome Caliente, while at the same time sending a lava flow down its flanks. This makes it an ideal study object for volcanology. A group of volcanologists from the University of Liverpool, in the UK, installed a network of geophysical stations around the volcano in November 2014, (you can find out more about that trip here). They’ve since been back to Guatemala to download the data recorded by the stations and carry out some maintenance. This photo diary blog post, by Felix Von-Aulock, a postdoctoral researcher at the University of Liverpool, gives a snap shot of what it is like to carry out research on an active volcano: it’s challenging, packed full of adventure and rewarding in equal mesure!

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

The Institute for Seismology, Volcanology, Meteorology and Hydrology (INSIVUMEH) are working hard to deliver updates on the activity of at least 3 erupting volcanoes to public, governmental bodies, and scientists. They do a really good job, despite the constant lack of funding, personel and equipment. This is our first stop on our way to Santiaguito, picking up equipment we left here last time, and catching up with Gustavo Chigna, a volcanolgist at INSIVUMEH.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

A few hours drive from Guatemala City, we finally see our destination, the Cerro Quemado/ Almolonga complex, with Santa Maria volcano (the tallest peak) in the background.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

It’s not all about the science! Guatemala is one of the biggest producers of coffee in the world and a lot of the volcanoes are surrounded by coffee plantations.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

While the volcanoes produce very fertile soils for the coffee to grow on, they can be very destructive. This farm at the base of Santiaguito has faced major hazards from lahars – torrents of hot or cold water, laden with rock fragments, ash and other volcaninc debris which hurtle down the flank of a volcano or valley following an eruption.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

The canyons fromed by the lahars cut right through the farm and the workers’ homes.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

Another hazard faced by the local communities is that posed by pyroclastic flows: high-density mixtures of hot, dry rock fragments and hot gases that move away from an eruptive volcaninc vent (as defined by the USGS).
Pictured above is the flow path of the pyroclastic flow of May 2014. The  flow paved the way for many Lahars which formed this canyon. The pyroclastic flow also nearly wiped out the volcano observatory and missed it only by 20m.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

In total we deployed 11 stations around the volcano. This trip’s main purpose was to maintain them and download the data aquired since they were installed in November 2014. We were excited to find that the first station we visited had actually been recording data until the week before we arrived. We were less excited to discover that bean plants were being planted right next to it, possibly leading to some ploughing noise in our data.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

Our room, three hours after our arrival. The chaos didn’t vanish, however, the smell got increasingly bad after 2 weeks of three guys sharing this room. Amongst the chaos, lots of expensive equipment and a kitten!

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

After sorting out supplies and taking care of the stations at the base of the volcano in Quetzeltenango, we finally started our hike towards the active dome. While we (Felix Von-Aulock, pictured in the far right and Adrian Hornby, a volcanology PhD student, picture in the centre) went down towards Santiaguito Dome, Oliver, also volcanology PhD student, (pictured second from the right),  went to the top of Santa Maria to film with a thermal camera. Don Geronimo, on the far left, is a local who helped Oliver carry equipment and water to the 3700m high peak. Armando Pineda (second f. l) was our guide down the tricky path to the dome.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

It feels good to be finally walking after weeks of preparation and travelling, despite the packs being pretty heavy and the long day ahead of us.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

The first two days were hard work: a constant mix of rain and sun, heavy packs we were not quite used to yet and some extra walks made us feel sore pretty quickly.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

When there was rain, the sun would come out quickly thereafter and the beautiful surrounding made up for the hard work.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

A morning view from our campsite below the chain of domes that was formed during the last century. The riverbed below had a pretty decent river in it just the night before during a thunderstorm. We got caught by that thunderstorm, trying to move car batteries uphill, but luckily decided to turn around to the tent before the river and potential lahars would cross our route.

Image credit: Felix Von-Aulock

Image credit: Felix Von-Aulock

The valley that leads to the active dome (Agua de Caliente) is an always changing channel, washed out by the frequent lahars. Good to have an experienced guide like Armando with us.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

The combination of a thin layer of ash and the frequent rain made some sections a bit tricky with the heavy packs.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

Here we’re digging out the first station, from here on we need to wear helmets as we’re about 300m from the active dome.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

The stations combine measurements of the sound (infrasound), the volcano’s seismicity and the tilt of the flanks of the volcano.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

The volcano is erupting frequently and every hour or so, we can see an ash plume rising into the sky above our heads.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

An eruption of the lava dome of Santiaguito observed from our tent around 300m from the crater.

Image credit: Felix Von-Aulock

Image credit: Felix Von Aulock

We also brought along a little quadcopter to take pictures of the dome. And although it was not the main subject of our mission it proved quite successful (we didn’t crash it!) Trying to follow a tiny spot in the sky is not easy though. And I just kept thinking:

“This must be one of the best jobs in the world, flying a little helicopter over an active volcano!”

By Felix Von Aulock , Postdoctoral researcher at the University of Liverpool

We are grateful to Rüdiger Escobar-Wolf for helping us improve an earlier version of this blog post.

Do you have some stunning field work photographs that you’d like to share with the wider community? Why not upload them to the EGU’s online open access geosciences image repository, Imaggeo? Geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/

Field work is an intrinsic part of the geosciences and yet the stories behind data aquisition are often left untold in scientific publlications. If you’d like to share your field work and/or lab tales, we’d love to hear from you! Part of what makes GeoLog a great read is the variety that guest posts add to our regular features, and we welcome contributions from scientists, students and professionals in the Earth, planetary and space sciences. Got an idea? If you would like to contribute to GeoLog, please send a short paragraph detailing your idea to the EGU Communications Officer, Laura Roberts  at roberts@egu.eu.