Can water scarcity cause the demise of civilisations?

Can water scarcity cause the demise of civilisations?

The ancient Mayan civilisation is somewhat of an enigma, and the demise of this advanced culture has remained a bit of a mystery – until recently.

A team of international researchers from various disciplines have been hard at work trying to fathom the goings on at that time – both in terms of the political turmoil and the climatic factors that may have influenced events that led to the downfall of such an advanced society. Their findings, published in Science reveal that the rise and fall of the Maya society was climate related.

“Here you had an amazing state-level society that had created calendars, magnificent architecture, works of art, and was engaged in trade throughout Central America,” said UC Davis anthropology professor and co-author Bruce Winterhalder. “They were incredible craftsperson’s, proficient in agriculture, statesmanship and warfare—and within about 80 years, it fell completely apart.”

Maya Political History

The scientists pieced together the political history by analysing hieroglyphics inscribed on ancient stone monuments, which are typically dated and depict significant events in their history, including celebrations, battles, and political unrest. From these inscriptions, they developed a war-index based on the use of keywords carved into the stone monuments, which gave them an overview of when this society was at peace and when things were more hostile.

“The historical texts carved on stone monuments provide a rich record of wars, marriages, accessions of kings and queens, and the capture and killing of warriors from competing groups. The events are incredibly well dated with the Mayan long count calendar system,” explains lead author, Professor Douglas Kennett, Pennsylvania State University, USA. “The end of this tradition of stone carving between AD 800 and 1000 marks the widespread collapse of the Classic Maya tradition.”

Did the Maya Civilisation Collapse Due to Climate Change?

It has been proposed before that the rise and fall of the Maya society was climate related, but there has never been any reliable proof to substantiate this. In order to test this theory and to get a clearer picture of what was driving hostility, and what eventually led to the collapse of this civilisation, the team needed to gather data on prevailing weather and climatic conditions at the time.

To get the information they needed the scientists collected a stalagmite from Yok Balum cave situated within close proximity to key Maya sites in Belize. By analysing the stalagmite in 0.1 millimetre increments using oxygen isotope dating techniques, they were able to determine rainfall patterns dating back 2,000 years to the present.

They then set about correlating hostile events from the war-index to the rainfall data collected from the stalagmite. These records reveal that the Maya society flourished between 300 – 660 AD, when rainfall was high, leading to a rising population and burgeoning cities. However, the downward spiral began around 660 AD when they were faced with climate change resulting in much drier conditions, which fuelled political competition, unrest, and war, leading to a collapse of the political system in 1000 AD. A prolonged drought between 1020-1100 AD is thought to have resulted in failed crops, famine, loss of life, and forced migration, which ultimately led to the fall of the Maya civilisation.

“Unusually high amounts of rainfall favoured an increase in food production and an explosion in the population between AD 450 and 660” explains Dr. Douglas Kennett, lead author and professor of anthropology at Penn State. “This led to the proliferation of cities like Tikal, Copan and Caracol across the Maya lowlands. The new climate data show that this salubrious period was followed by a general drying trend lasting four centuries that was punctuated 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 centres (referred to as the Maya collapse) and may be associated with widespread population decline in the region.”

“The effects of climate change are complex and play out over multiple time scales,” he added. “Abrupt climate change is only part of the story. In addition to climate drying and drought, the preceding conditions stimulating societal complexity and population expansion helped set the stage for later stress on their societies and the fragmentation of political institutions.”

The Impact of Society on Hydrology

A more recent study conducted by scientists from the Vienna University of Technology (TU Wein) also implicates water scarcity for the demise of the Mayan civilization. In this study, which was recently published in the journal Water Resources Research, the researchers modelled the connection between society and water — particularly the impact human society has on water resources — and found that the irrigation systems that provided the Mayans with water during times of drought may have contributed to their downfall by making them more vulnerable to climate-related catastrophes.

“Water influences society and society influences water,” explains Linda Kuil, a PhD student of the Vienna Doctoral Programme on Water Resource Systems at TU Wien and lead-author of the study. “The water supply determines how much food is available, so in turn affects the growth of the population. Conversely, population increases may interfere with the natural water cycle through the construction of reservoirs, for example.”

It is well known that the Mayan’s had advanced engineering skills and built reservoirs to store and deliver water for their needs. But these water reservoirs may have been both a blessing and a curse. The water stored within these structures may have provided short-term relief during times of drought, allowing the population to continue to grow. However, this growing population may in fact have become more vulnerable to extended periods of drought because of them. The water demand of each person and the way people used and managed these water resources no doubt remained unchanged, even though the population continued to increase. Under this scenario, the models show that in the event of another dry period, the population would decline even more dramatically than if reservoirs weren’t built to store water.

Lessons From the Maya

While we may never truly know what led to the collapse of the Mayan civilisation, these two studies indicate that drought and water scarcity may have played a key part.

There are many lessons to be learnt from the Maya. The collapse of the Mayan civilisation illustrates the consequences of a society that fails to adapt to climate change. When resources essential for survival (food and water) are scarce, more people scramble for these limited resources, leading to friction, hostility and war.

It’s a cautionary tale about how fragile our political structure might be,” says Winterhalder. “Are we in danger the same way the Classic Maya were in danger? I don’t know. But I suspect that just before their rapid descent and disappearance, Maya political elites were quite confident about their achievements.”

By the same token, modern technology may make it easier to access natural resources such as water, but if these crucial water resources are not used sparingly, human societies can become extremely vulnerable in periods of drought when water is scarce.

“When it comes to scarce resources, the simplest solutions might turn out to be superficial and not always the best ones,” Linda Kuil believes. “You have to change people’s behaviour, reassess society’s dependency on this resource and reduce consumption — otherwise society may in fact be more vulnerable to catastrophes rather than safer, despite clever technical solutions.”

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