Ancient pollen and charcoal preserved deep in the sediment reveal the impact of droughts and fires during what is known as the pyramid-building time.
"Humans have a long history of having to deal with climate change," said Christopher Bernhardt, a researcher with the U.S. Geological Survey. "Along with other research, this study geologically reveals that the evolution of societies is sometimes tied to climate variability at all scales -- whether decadal or millennial."
One of those climate events was an abrupt and global mega-drought around 4,200 years ago, a drought that had serious societal repercussions, including famines, and which probably played a role in the end of Egypt's Old Kingdom, a USGS release said Thursday.
"Even the mighty builders of the ancient pyramids more than 4,000 years ago fell victim when they were unable to respond to a changing climate," USGS Director Marcia McNutt said. "This study illustrates that water availability was the climate-change Achilles Heel then for Egypt, as it may well be now for a planet topping 7 billion thirsty people."