Even ancient Egypt’s mighty pyramid builders were powerless in the face of the famine that helped bring down their civilization around 2180 BC. Now evidence gleaned from mud deposited by the River Nile suggests that a shift in climate thousands of kilometers to the south was ultimately to blame-and the same or worse could happen today.
The ancient Egyptians depended on the Nile’s annual floods to irrigate their crops. But any change in climate that pushed the African monsoons southwards out of Ethiopia would have been diminished these floods.
Dwindling rains in the Ethiopian highlands would have meant fewer plants to stablise the soil. When rain did fall it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment from the White Nile.
The Blue Nile mud has a different isotope signature from that of the White Nile. So by analyzing i
A. Change of climate.
D. Population growth.