Holocene trends in Nile Delta fire regimes driven by cropland expansion and reduced precipitation

Fire played a pivotal role in promoting early agricultural development in ancient Egyptian societies. In the Nile Delta, since the Predynastic period, fires have predominantly been initiated by human activity. However, the long-term alterations in precipitation patterns and Nile floods might also have significantly influenced the evolution of the human-induced fire regime. Here we investigate 8000 years (10,000 to 2000 BP) of fire activity in the Nile Delta using a composite sequence based on cores taken from the Predynastic sites of Buto, Sais and Kom El-Khilgan. We compared and contrasted the long-term evolution of fire activity with precipitation data, Nile flow dynamics and the emergence/development of agriculture to disentangle the factors that modulated the occurrence and intensification of fires during the Holocene. Until 6100 ± 70 BP, sustained precipitation, in tandem with significant flooding of the Nile, was the foremost factor inhibiting human settlement and the use of fire in the delta. During the period spanning from 6100 ± 70 to 4700 ± 70 BP, weakening Nile discharge and increasing human-induced fire significantly promoted agriculture. Since 4700 ± 70 BP, cropland expansion, driven by declining intensity in Nile flow and reduced precipitation, has contributed substantially to the upward trend in fire activity over the delta. This increase in burned areas likely resulted from the need for sustained agricultural production to cope with rapid population growth in Egypt and the socio-economic changes that occurred during the Dynastic period. The Nile Delta data are consistent with those of the eastern Mediterranean, suggesting that the entire region underwent significant transformation between 5500 and 4500 BP.