The Kings in Egypt kept control of the populace through the Priests who would ‘predict’ the flooding of the Nile, and attribute the flooding to the refusal of the ‘people’ to cooperate with the King’s wishes.
The overall trend is up - but the upward trend has stalled - thus the need to use a “trick” to “hide the decline”.
30 years ago these same guys were predicting a coming Ice Age.
That was also supposedly all our fault.