Lifeboat Foundation

Evolution of the iodine cycle and the late stabilization of the Earth’s ozone layer https://www.pnas.org/doi/10.1073/pnas.

If you like the smell of spring roses, the sounds of summer bird song, and the colors of fall foliage, you have the stabilization of the ozone layer to thank for it. Located in the stratosphere, where it shields Earth from harmful ultraviolet radiation, the ozone layer plays a key role in preserving the planet’s biodiversity.

Now we may have a better idea of why that took so long—more than 2 billion years—to happen.

According to a new, Yale-led study, Earth’s early atmosphere hosted a battle royale between iodine and oxygen—effectively delaying the creation of a stable ozone layer that would shield complex life from much of the sun’s ultraviolet radiation (UVR).