desertify

As verbs the difference between decertify and desertify

is that decertify is to remove the certification of while desertify is (of a geographical region) to become desert.

As a noun desert

is desert.

As an adjective desert

is deserted.

As a verb desertify is

(of a geographical region) to become desert.

As verbs the difference between desertify and vulcanize

is that desertify is (of a geographical region) to become desert while vulcanize is to treat rubber with heat and (usually) sulphur to harden it and make it more durable.