This seems like one of those cases where what is really the most environmentally-friendly option is not at all clear when you stop to think about it.

Sure, plastic bags aren't biodegradable. But from what I've read, *nothing* really degrades in a landfill if it's more than a couple feet below the surface. And a single plastic bag has much less mass and volume than a single paper bag.

The only clearly eco-friendly alternative is to take your own reusable bags with you to the store, but really--who does that?

Great idea for a post :)!

And with paper bags, you have that whole "chopping down trees" thing.

Eric's right. The most environmentally-friendly way to shop is to bring your own resuable bag. I know no one who does that.

Does anyone else see the Orwellian tone to Craig Noble's statements? Statists everywhere love showing people "a way out of a false choice".

I take my own bags to the store. I use the fabric bags that I get when I go to conferences. Not an inconvenience, not a problem.
I haven't seen a paper bag in the grocery in several years, so I was unaware of any option in the present.
As is usual, SF/CA leads on environmental issues. Not always for the best, but not often right on the money (e.g. smog inspections for autos, which I think everey state should have)
SF supervisors also point to many plastic bags in the streets and, particularly around the waterfront, birds and sea animals getting caught up in the bags. I don't think that would happen with paper, although I'm not sure of the impact of the biodegradable plastics.

Cheers,

Dave

Three cheers for anyone who takes proactive stances to protect wildlife and the environment altogether - but inn the case of a city ordinance banning plastic bags, I just don't see how the potential benefit is worth the sacrifice in choice. I mean, we're talking about biodegradable plastic bags! It could be argued that it would be better environmentally to let trees live, so they can fix CO2. There's just no way to determine the environmental impact here. Why mandate one environmentally hazardous behavior (deforestation) over another (plastic-bag proliferation?)? It seems purely arbitrary.

Actually Chuck what the ordinance is designed to do is to require a switch from the current non-biodegradable plastic to newer designs that are biodegradable. The grocery industry is resisting because biodegradable bags are more expensive. So, in effect, the consequence is to keep choice the same (plastic, fabric, paper) but to change the make-up of the plastic so that it degrades in landfills and on the surface.

I'm pretty skeptical that there is a loss of liberty (per choice) in this issue. As for trees, we can sustain trees pretty comfortably and have the same number (roughly) that we did a century ago. While I wouldn't advocate clear cutting the little old-growth that is left, cost to C02 conversion isn't a real factor. Moreover, it may open the technology to other materials that can be used to produce bags. Heck, I'd buy a nice hemp grocery bag to carry with me.

Cheers,

Dave

Why mandate one environmentally hazardous behavior (deforestation) over another (plastic-bag proliferation?)?

They aren't. What they are trying to mandate is a shift from the current types of plastic bags over to biodegradeable plastic bags which can be composted. Shoppers won't really notice a difference in the end result thanks to quality control, and the only difference on the store's end would be the cost per metric ton of plastic bags going up by however much. It would seem that the smarter way to go about this would have been with subsidies/tax breaks to address that very fact. Plus you get more flies with honey and all that.

As I said earlier, I've read that the degradation rate of "biodegradable" materials in landfills is much lower than assumed when the stuff gets buried under a couple feet or more of trash (due to lack of oxygen, etc.) It would probably be a lot faster in a backyard compost pile, but how many San Franciscans have those?

Concern about animals getting caught in the bags sounds more valid, but that's not really the fault of the bags per se, but that people aren't disposing of them properly. Even so, is this really a significant problem, and will the bags degrade quickly enough to remediate it?

For whoever's interested, here's an online copy of a Smithsonian article about University of Arizona research on what happens to trash in landfills:

http://www.tulane.edu/~bfleury/envirobio/readings/rathje/rathje.htm

It's probably more important that the bags degrade in the ocean than in landfills. There's a big concern about how many of these bags worldwide become trash floating in the oceans. It would be nice if they biodegrade in landfills also. But let's face it--plenty in landfills doesn't biodegrade, and we expect those places to be filled with trash.