Re: Can the Ozone layer be replaced with an artificial layer

Ozone (O₃) protects the earth's surface from dangerous ultraviolet radiation. When ultraviolet light strikes ozone, it breaks up into two pieces and absorbs the light. These pieces eventually reconnect. However, some chemicals, especially chlorofluorocarbons (CFCs) can break down ozone, destroying it.

I don't know of anything but ozone which could do what ozone does. If we want to make an artifical ozone layer, we'll have to use real ozone, no substitutes. Ozone is a very hazardous material in bulk: it is poisonous, and in liquid form will explode if you bump its container.

There are very roughly 2 billion tons of ozone in the atmosphere. This is a huge amount: you'd need 20 million 747 jet airplanes to carry this much ozone up to the stratosphere -- this is impossible, even ignoring the serious problems with producing, storing, and delivering this much ozone.

It is probably impossible for humans to create an artifical ozone layer: the best we can do is try to stop the CFCs which destroy ozone from reaching the ozone layer. The simplest way to do this is to stop using CFCs. However, many CFCs will stay in the atmosphere for a century after we stop producing them. Various methods have been proposed to "clean" the atmosphere of CFCs. These include:

• Laser beams: A process called "infrared multiphoton dissociation" can break apart CFCs when they pass through a laser beam with a very specific "color". By setting up a system of lasers and mirrors on two mountainsides separated by a valley, one could break up CFCs in the air passing through the valley. Unfortunately, this technique would be incredibly expensive, and would probably cause environmental problems.
• Alkane reactions: Active chlorine (which is made when CFCs break apart, and is the molecule which actually destroys ozone) will react with other things besides ozone. By dumping large amounts of ethane or propane (popular cooking and heating fuels) into the stratosphere, one can remove active chlorine fairly rapidly. My sources suggest that 50,000 tons of propane, if dumped into the stratosphere, would repair the ozone hole for a season. This is much easier to do than repairing the hole by replacing the ozone: 500 plane flights might be enough. Also, hydrocarbons are much easier to work with than liquid ozone. It's still a huge project, and there are many uncertainties involved.

I got the information on CFC mitigation strategies from one of my favorite books: Terraforming, by Martyn Fogg.