Adam Clarke on Genesis 41:54

The seven years of dearth began to come - Owing in Egypt to the Nile not rising more than twelve or thirteen cubits; (See Clarke on Gen 41:31 (note)); but there must have been other causes which affected other countries, not immediately dependent on the Nile, though remotely connected with Egypt and Canaan.

The dearth was in all lands - All the countries dependent on the Nile. And it appears that a general drought had taken place, at least through all Egypt and Canaan; for it is said, Gen 41:57, that the famine was sore in all lands - Egypt and Canaan, and their respective dependencies.