[Rubinsalamander]

That large band exists only for mediterran regions. Some regions are already living on the hot/cold edge

[dalbasal]

The band of "habitable by humans" is as wide as you could want. People live in Alaska and in Libya.

The problem is that stuff is adapted to the way things are. Alaskan trees, bugs, mail services and whatnot are all adapted to snow and ice and such. Bugs go dormant, mailmen hibernate. Libyan mailmen would freeze to death is they got Alaskan weather. Alaskan trees would die if they got Libyan weather. Crops would fail, etc.

[Terr_]

> Bugs go dormant, mailmen hibernate.

Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds.