Classic Maya Collapse - Theories - Drought Theory

Drought Theory

Mega-droughts hit the Yucatán Peninsula and Petén Basin areas with particular ferocity, for several reasons:

1. Thin tropical soils, which decline in fertility and become unworkable when deprived of forest cover;
2. Regular seasonal drought, drying up M+D surface water;

The colonial Spanish officials accurately documented cycles of drought, famine, disease, and war, providing a reliable historical record of the basic drought pattern in the Maya region.

Climatic factors were first implicated in the Collapse as early as 1931 by Mayanists Thomas Gann and J.E.S. Thompson. In The Great Maya Droughts, Richardson Gill gathers and analyzes an array of climatic, historical, hydrologic, tree ring, volcanic, geologic, lake bed, and archeological research, and demonstrates that a prolonged series of droughts most likely caused the Classic Maya Collapse. The drought theory provides a comprehensive explanation, because non-environmental and cultural factors (excessive warfare, foreign invasion, peasant revolt, less trade, etc.) can all be explained by the effects of prolonged drought on Classic Maya civilization.

Climatic changes are, with increasing frequency, found to be major drivers in the rise and fall of civilizations all over the world. Professors Harvey Weiss of Yale University and Raymond S. Bradley of the University of Massachusetts have written: "Many lines of evidence now point to climate forcing as the primary agent in repeated social collapse." In a separate publication, Weiss illustrates an emerging understanding of scientists:

Within the past five years new tools and new data for archaeologists, climatologists, and historians have brought us to the edge of a new era in the study of global and hemispheric climate change and its cultural impacts. The climate of the Holocene, previously assumed static, now displays a surprising dynamism, which has affected the agricultural bases of pre-industrial societies. The list of Holocene climate alterations and their socio-economic effects has rapidly become too complex for brief summary.

The drought theory holds that rapid climate change in the form of severe drought brought about the Classic Maya collapse. According to the particular version put forward by Gill in The Great Maya Droughts,

Yucatecan lake sediment cores ... provide unambiguous evidence for a severe 200-year drought from AD 800 to 1000 ... the most severe in the last 7,000 years ... precisely at the time of the Maya Collapse.

Climatic modeling, tree ring data, and historical climate data show that cold weather in the Northern Hemisphere is associated with drought in Mesoamerica. Northern Europe suffered extremely low temperatures around the same time as the Maya droughts. The same connection between drought in the Maya areas and extreme cold in northern Europe was found again at the beginning of the 20th century. Volcanic activity, within and outside Mesoamerica, is also correlated with colder weather and resulting drought, as the effects of the Tambora volcano eruption in 1815 indicate.

Mesoamerican civilization provides a remarkable exception: civilization prospering in the tropical swampland. The Maya are often conceived as having lived in a rainforest, but technically, they lived in a seasonal desert without access to stable sources of drinking water. The exceptional accomplishments of the Maya are all the more remarkable because of their engineered response to the fundamental environmental difficulty of relying upon rainwater rather than permanent sources of water. “The Maya succeeded in creating a civilization in a seasonal desert by creating a system of water storage and management which was totally dependent on consistent rainfall.” The constant need for water kept the Maya on the edge of survival. “Given this precarious balance of wet and dry conditions, even a slight shift in the distribution of annual precipitation can have serious consequences.”

Water and civilization were vitally connected in ancient Mesoamerica. Archaeologist and specialist in pre-industrial land and water usage practices, Vernon Scarborough, believes water management and access were critical to the development of Maya civilization.

Critics of the drought theory wonder why the southern and central lowland cities were abandoned and the northern cities like Chichen Itza, Uxmal, and Coba continued to thrive. One critic argued that Chichen Itza revamped its political, military, religious, and economic institutions away from powerful lords or kings. Inhabitants of the northern Yucatán also had access to seafood, which might have explained the survival of Chichen Itza and Mayapan, cities away from the coast but within reach of coastal food supplies. Critics of the drought theory also point to current weather patterns: much heavier rainfall in the southern lowlands compared to the lighter amount of rain in the northern Yucatán. Drought theory supporters state that the entire regional climate changed, including the amount of rainfall, so that modern rainfall patterns are not indicative of rainfall from AD 800 to 900. LSU archaeologist Heather McKillop found a significant rise in sea level along the coast nearest the southern Maya lowlands, coinciding with the end of the Classic period, and indicating climate change.

David Webster, a critic of the megadrought theory says that much of the evidence provided by Gill comes from the northern Yucatán and not the Southern part of the peninsula, where Classic Maya civilization flourished. He also states that if water sources were to have dried up, then several city-states would have moved to other water sources. The fact that Gill suggests that all water in the region would have dried up and destroyed Maya civilization is a stretch, according to Webster.

A study published in Science in 2012 found that modest rainfall reductions, that amount to only 25 to 40 per cent in annual rainfall, may have been the tipping point to the Mayan collapse. Based on samples of lake and cave sediments in the areas surrounding major Mayan cities, the researchers were able to determine the amount of annual rainfall in the region. The mild droughts that took place between AD 800-950 were enough to rapidly deplete seasonal water supplies in the Yucatán lowlands, where there are no rivers.