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.
Sometimes you have to change your vantage point to really see something.
The New York Times today reports on the work of Diane and Arlen Chase, who spent more than 20 years cutting through the Central American jungle to survey the Ancient Mayan city of Caracol in present-day Belize. But when they were turned on to the possibility of using flyover missions equipped with laser technology that could see to the jungle floor, their research accelerated dramatically.
In only four days, a twin-engine aircraft equipped with an advanced version of lidar (light detection and ranging) flew back and forth over the jungle and collected data surpassing the results of two and a half decades of on-the-ground mapping, the archaeologists said. After three weeks of laboratory processing, the almost 10 hours of laser measurements showed topographic detail over an area of 80 square miles, notably settlement patterns of grand architecture and modest house mounds, roadways and agricultural terraces [The New York Times].
Given such dramatic results, you might think the scientists would have started working from above earlier. After all, learning by bouncing lasers around isn’t new: Satellites have measured the Antarctic ice by reflecting lasers of the sheet and back into space, then measuring how long it took. Scientists have bounced lasers off reflectors that U.S. and Russian moon missions left behind, measuring the moon’s slow progression away from the Earth.