Ancient Mayan Drought Provides a Cautionary Tale
Research suggests that the civilization’s collapse was associated with extended dry spell
Cambridge University and University of Florida researchers believe they have finally isolated the cause of Mayan civilization’s mysterious collapse in the ninth century, when dynasties fell and the Maya abandoned their magnificent limestone cities. The Maya continued to inhabit the jungles of the Yucatan peninsula in small communities, but never again achieved the robust economy and the heights of art and monumental architecture seen in the Classic Period. In our own time of water stress and climate change, the research findings may serve as a cautionary tale: Drought may well have brought down the Maya.
With support from the European Research Council, the researchers pioneered a technique for measuring isotopes of water captured in gypsum. During times of drought, gypsum accretes in Lake Chichancanab in the Mexican state of Yucatán, which was once the heart of Mayan civilization. The researchers discovered that at the time of the collapse, yearly rainfall had decreased to between 41% and 54% of today’s levels, and as much as 70% lower during the worst of it, which could have decimated maize crops.
The history of the drought theory
Climate’s role in the Mayan collapse has been controversial because records are limited, but the paper’s lead author, Nick Evans, a doctoral student in Cambridge’s Department of Earth Sciences, explained that the “study represents a substantial advance as it provides statistically robust estimates of rainfall and humidity levels during the Maya downfall.”
Competing theories of the Mayan collapse abound, including war, invasion, environmental depletion, and deteriorating trade, but the researchers were able to piece together climate records that showed a correlation of the Maya’s fall with a long and deep drought. In 1995, the paper’s senior author, Professor David Hodell, director of Cambridge’s Godwin Laboratory for Palaeoclimate Research, documented the first physical evidence concerning the drought at Lake Chichancanab and the Mayan civilization.
In the current study, Hodell and colleagues use the new technique to estimate the depth of the drought and to create a full hydrological model of the Terminal Classic Period, including rainfall and relative humidity. Water molecules in gypsum’s crystalline structure provide a highly accurate record of the range of isotopes in ancient lake water. During drought conditions, more water evaporates. Lighter water isotopes evaporate quickly, and the lake water becomes heavier. The presence of more heavy isotopes like oxygen-18 and hydrogen-2, therefore, indicates drought.
Present Water Scarcity
With evidence that the great Mayan civilization ended in drought, it is hard not to think of how this year, for the first time, a major, modern city of the developed world came to the very brink of simply running out of water after three years of relentless drought. Only austere water rationing and a massive use of desalination and water reuse saved Cape Town from “Day Zero,” the day the city’s taps would have run dry.
Major Australian cities, as well, recently went through a massive desalination infrastructure build-out to counter a serious 10-year drought.
Israel is entering a sixth year of drought. Even in a country that leads the world in desalination and water recycling, its largest natural water source, the Sea of Galilee, is dangerously close to reaching low water levels that could cause severe ecological damage.
All projections through 2050 see global trends of continued, worsening water scarcity driven by climate change, growing population, agriculture, industry, and other human activities. Correlating drought with the fall of the Maya could provide a call to action as we search for new ways to deal with water shortage.
Fortunately, recent developments in water and wastewater treatment technologies may hold the key to a water-secure future, lowering costs and energy requirements, and bringing sustainable solutions to wherever they are needed.