Storage

If you allow yourself to alter the view, polyethylene could be taken as some permanent storage of carbon dioxide, a compound that would keep the major greenhouse gas bound to the soil rather than being released to the atmosphere, which would be inevitably the case if it is degraded.

Now you see the beauty of plastic bags ?

You think that's crazy ? I'm not alone. People are beginning to consider long-term carbon dioxide storage by using the deep sea sediment as the reservoir. (Go read Goldberg DS, et al. Proc Natl Acad Sci USA 2008; 105: 9920-9925 and a few other related articles.)

You may argue, "Plastic bags are bad because they are unsightly and may harm some types wildlife if not disposed properly."

My salute to your excellent knowledge on the official reasons against plastic bags. But, your lips betrayed your mind - the problem is improper disposal of this excellent reservoir of greenhouse gas, not the thin films of plastics themselves.

By the way, most of the industries are already charged for sewage disposal. As to the new Plastic Bag Tax, is it then a kind of double taxation ?

PS. My discussion in these two days are, of course, based on the assumption that greenhouse gas is bad because it is the direct cause of global warming. You may hold a different view. (Seriously, I do.) But that's another story.