Nerve, Skin, Cyclins, Cancer
This question has a two part answer. The first part is that an asteroid hitting the earth and the second part is massive volcanoes erupting around the world.
The structure of the lipid bilayer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.
It cause a chain reaction and kills off the organisms