It can repair itself, we just needed to stop putting aerosols into the air. Same deal now, apparently China needs to get its shit together and stop using the chemical the whole world already decided to stop using.
Yep, it's pretty amazing how much not destroying the environment helps it recover... although the closer we get to a collapse, the more that ability to bounce back diminishes
Literally every aspect of our world is in a balance... Everything wears down over time, so the current state is basically a homeostasis between biological, geological, and astrological forces. The problem is that humans act on a far shorter time scale - 100 humans could cut down trees faster than a forest can regrow, 8 billion can change the atmospheric composition in a decade or two