The stratospheric ozone layer plays a crucial role in filtering out harmful ultraviolet (UV) radiation from the sun. If this layer were to decrease, it would result in an increase of UV radiation reaching the ground level. This, in turn, could lead to a rise in skin cancer cases among humans and damage to terrestrial and marine biological systems.

The discovery of the Antarctic ozone hole was a clear indication that human-made ozone-depleting substances were affecting the stratosphere in a profound way. These substances, along with polar stratospheric clouds, had exceeded a critical threshold, changing the Antarctic stratosphere. However, due to the actions taken as a result of the Montreal Protocol, it seems that this is the only boundary that is on a positive path towards maintaining a safe operating space.