Dear Cecil,
I’m new to your website and have enjoyed the columns immensely. I am especially impressed with how thorough your answers are. Very informative.
That is why your answer to Mojo’s question about cow farts destroying the ozone layer was so perplexing to me. My understanding of the most current environmental problems is that there are two separate phenomena. Ozone destruction, and the greenhouse effect.
The greenhouse effect is caused by excess gasses (mostly Carbon dioxide)which allow sunlight to pass into the atmosphere but keep it from bouncing back into space. therefore alllowing the earth’s atmosphere to warm up. This effect is much the same as leaving the windows closed in your car on a sunny day. It is also what keeps greenhouses warm on cold days. Hence “Greenhouse effect”.
Ozone destruction is caused chiefly by Chlorofluorocarbons the two biggies are Freon-12, the old air-conditioning refrigerant and Trichloroethane, an industrial solvent.
Ozone is O-three. Three oxygen atoms bonded together. It largely comprises a very thin layer of the upper stratosphere (about fifty miles up) When ultraviolet radiation from old Sol hits it it breaks up into O-two (common oxygen) and one oxygen atom. Later, that unpaired oxygen bonds back with the O-two to form ozone again. The importaht thing is that the ultraviolet radiation is changed in the process into a lower wavelength, less harmful form of light.
The Ozone layer doesn’t stop ALL UV radiation, but it stops enough to prevent some pretty serions sunburns, skin cancers, etc… Moat plants can also be harmed by excess UV radiation.
Unfortunately, other chemicals can interfere with the production of ozone. Free chlorine (and Fluorine) can bond with that extra oxygen preventing it from reforming into ozone.
The reason Chlorofluorocarbons are so harmful to the ozone layer is that they are so stable. They were created to be so ( if your air-conditioner leaks, it won’t kill you or start a fire. same with those solvents) Most other chlorinated compunds will combine with water to form some kind of acid and come down as acid rain (all rain is acicdic for this reason but that’s a whole 'nother subject). But Chlorofluorocarbons hang around so long until they find themselves in the stratosphere where they will eventually degrade releasing free chlorine and fluorine.
So, while your answer was correct, it wasn’t the answer to Mojo’s question. Ozone depletion and the greenhouse effect are two separate phenomena. Ozone depletion is also one of my favorite topics ever since a certain large conservative AM radio talk-show host made hay from “debunking the ozone myth”. It’s not a myth.
MomboCat
Sure it was. Mojo’s metaquestion (the question he would have asked if he hadn’t had his head up his butt) was, is it true flatulence from cows and other critters is messing up the earth’s atmosphere? He confused the greenhouse effect with ozone depletion, and perhaps I should have hammered on that a bit more. But I answered the question he meant to ask.