The Mayan rain god Chac
Droughts do far worse than brown our lawns—the water shortages and crop damage they mete out, and the fires fed by dry conditions, have effects that last long after rain returns. These events may even have civilization-destroying powers: although doubts remain, many researchers consider drought one of the leading contributors to the collapse of the Maya. And a new study published in Geophysical Research Letters finds that by cutting down forests, Mayans may have directly contributed to the droughts that brought about the downfall of their society.
Like modern civilizations, Mayans felled trees in order to harvest the raw material and clear land for cities and crops. Researchers modeled how this deforestation affected local climate conditions with computer simulations. Cleared land absorbs less solar energy, which means it releases less moisture to contribute to rainfall. By comparing untampered or regrown forest to reconstructions of the tree cover during Mayan occupation, researchers found that razed land could have reduced annual rainfall by 5 to 15 percent. This means that of the estimated drought during the height of Mayan civilization, 60 percent of the rainfall decrease was likely due to deforestation.
The Xultun scribe’s chamber, with A, B, and C showing the locations of the calculations.
In a small closet-like chamber off a central plaza of the ancient Mayan city of Xultun, a scribe once sat with a paintbrush in hand.
On the north walls of the room, he painted an apparent self-portrait, facing a figure with an elaborate headdress, perhaps a ruler. But on adjacent walls, he and his successors, starting in about 800 C.E., painted and inscribed various astrological calculations. They are very similar to those found in the Dresden Codex, one of the most famous extant Mayan books, which contains numerous astrological and ritualistic cycles and is thought to have been copied from older books sometime between the 11th and 15th centuries. The markings on the scribe’s walls in Xultun, unveiled last week in a paper in Science, represent the earliest known depictions of some of these calculations.