Assume:
Assume you are Johannes, and assume you have lost your marbles.
Oh, sorry, I'm repeating myself.
Whilst your comment is manifestly true, it is irrelevant since there is no likely manner in which Earth will "lose" its atmosphere short of the Sun entering its Red Giant phase in about 5 billion years from now, at which time surface conditions will be rather hotter than the planets we were discussing.
If this is a thinly veiled hint about your stupuid radioactivity ideas, you know where to file it.