It's easy to get pushed over when you're already on the edge

By BJ Bjornson

An interesting new study out showing that the collapse of the Maya civilization was accompanied not by a severe drought, but rather a relatively mild constraint on their water supplies.

Now, two Earth scientists have carefully analyzed rock samples from the Yucat� which revealed water levels in local lakes, as well as chemical traces that show likely rainfall over the decades of the collapse. What the scientists found was more evidence that the region suffered from drought during the typically rainy summers � but the drought was fairly mild. There were probably fewer hurricanes in the ocean driving rainstorms to land. In a paper published today in Science, researchers Mart�Medina-Elizalde and Eelco J. Rohling call it "a succession of extended drought periods interrupted by brief recoveries."

Is it really possible that a mild drought, no matter how many centuries it lasted, could really topple an empire? After all, civilizations in Europe have endured everything from plagues to the Little Ice Age, and people did not abandon the cities.

Medina-Elizalde and Rohling suggest:

If these repeated episodes of drier climate had a significant role in the fate of the Classic Maya civilization, as suggested by archaeological evidence, then this would imply that the ecological carrying capacity of the Yucat�Peninsula is highly sensitive to precipitation reductions.

In other words, it's possible that it didn't take much of a drought to usher in a catastrophic series of crop losses or other environmental problems. And these problems, in turn, could foment dramatic social upheavals.

This is important for more than the Yucatan, which may see a repeat of such conditions due to Climate Change, because while we may not be entirely certain what the carrying capacity of the Earth is for humanity, in many cases we are already over-consuming what the planet can produce on a renewable basis, not to mention our drawing down of non-renewable resources. All of which is to say that even a relatively minor disruption could cause massive damage to our civilization as it did the Maya, and at the rate we�re going, the disruption Climate Change is going to cause will be far more than minor.