This Mayan city died out after inadvertently poisoning its own water supply. Our…

The Mayan civilization in southern Mexico and northern Central America began to take form around 4,000 years ago, and was marked by the first stabs at settlement and farming in the area. Though this was not an organized collective or alliance that called itself “Mayan” but an umbrella term for the peoples of the region, we can still say that in its “classic” phase – from about the year 300 to 1000 – the Mayan civilization would create great urban centers and even city-states, featuring monumental architecture, art, and hieroglyphic writing going back as much as 2,400 years.

And then, around a thousand years ago, it collapsed for reasons still being elucidated to this day. Archaeologists generally agree that the causes of the Mayan civilization decline include war, overpopulation, unsustainable practices to feed that population, and protracted drought.

Now a team of archaeologists reports in Nature that in Tikal, one of two major Mayan city-states, the water reservoirs had become contaminated with heavy metals and toxic algae. That likely contributed to the city’s sudden collapse in the ninth century.

Over a thousand years later, we can’t say we’re doing better. The ancient Mayans could not have grasped the broader climatic causes, or be able to forecast decades into the future. Today, we have technology and forecasting abilities, yet mega-cities around the world are running out of fresh water – from Cape Town in South Africa to Chennai and Bangalore in India, to Mexico City (you know where), São Paulo in Brazil, Beijing in China, Jakarta in Indonesia to London, and the list goes on. Have we (humans) taken sustainable measures that will ascertain a sustainable fresh water supply for human and beast? We have not.

Back in ancient Tikal, one of the foremost of the ancient Maya cities, write David Lentz of the University of Cincinnati and team, the water reservoirs in the city’s heart became so polluted with mercury, phosphate and cyanobacteria that the water would have been poisonous. This contribution to the demise of the city, whose remains are located in northern Guatemala, hadn’t been known until now.

Mega-drought in Mesoamerica

The climatic upheavals of Mesoamerica are recognized. In fact, in 2012 a separate team proposed in Science that the Mayan populations had been spurred to massively expand by anomalously high rainfall starting around 400. But from about 660, a trend of aridification began, culminating in terrible mega-droughts that lasted decades, from 820 to 870.

And thus the land lost its ability to sustain the population that had been fruitful and multiplied in wetter times.

Nor could the inhabitants of Tikal tap the groundwater: it was a good 200 meters (nearly 660 feet) below the surface and they didn’t have the technology. Nor did they have access to any rivers…