Some studies indicate that many processes on Earth are the result of natural feedback loops. This can happen in nonbiological systems. For example, the polar ice reflects the sun’s rays, keeping the planet cool; disappearing ice at the North pole could mean that more of the sun’s heat is absorbed by the dark sea underneath, warming the planet more quickly. Taking biological systems out of their ‘comfort zone’, which is based on feedback, can also result in drastic consequences. For example, though atmospheric scientists have previously been at great pains to distinguish the ‘hole in the ozone layer’ from the greenhouse effect when explaining these issues to the public, this problem could potentially affect climate indirectly.
The ozone layer, which is generated by the sun’s UV rays interacting with oxygen in the atmosphere to form a high energy molecule of ozone (O3), in turn blocks ultraviolet or UV rays, which can damage life. CFCs (chlorofluorocarbons) used as refrigerants and propellants react with ozone and turn it back into oxygen, which lets the UV rays through. UV damage is felt particularly harshly by marine ecosystems, which are extremely important carbon ‘sinks’, taking the greenhouse gas CO2 out of the atmosphere. Marine ecosystems are also very sensitive to ocean temperatures, so a warming effect that is worsened by disappearing polar ice (from the first example) could lead to more dramatic changes more quickly. It’s worth remembering that life has completely switched the atmosphere of the Earth at least once: when plants started to produce oxygen through photosynthesis (the basis of life today, because it makes the oxygen we breathe), many organisms became extinct because they were unable to exist in oxygen rich atmospheres.