Why must the era of internal combustion engines end?

Why must the era of internal combustion engines end?

The Earth is quite large, but the layer of dense air around it is not very thick, reaching a height of about 11 kms, where 3/4 of the planet's air mass is located. Compared to the radius of the Earth (approx. 6371 kms), the denser air layer is only about 0.17%. For example, on a globe with a diameter of 30 cm, only a layer of about 1/4 mm would correspond to this, which is comparable to the thickness of a thin layer of dust or a sheet of paper.