There are, however, lots of externalities associated with alternatives to single-use plastic which we do know are harmful.

There is an excellent 2018 study [1] which enumerates these. A memorable finding is that an organic cotton shopping bag must be reused 20,000 times before it breaks even with a single-use plastic bag.

(This is not to say that a plastic bag would be likely to end up in the sea or eaten by a bird, but it has somehow become common belief that that is the case).

[1]: https://www2.mst.dk/Udgiv/publications/2018/02/978-87-93614-...

Please read your actual article. The cotton bag must be reused 52 times to break even in terms of climate change and the 20,000 number is "all indicators", of which it states that " The highest number is due to the use of water resource, but also to freshwater and terrestrial eutrophication." [page 18]. There's some serious flaws with not counting water as a renewable resource. As for eutrophication, the author also doesn't consider the carrying capacity of the environment to recycle phosphorous and other other agriculture byproducts.

> There's some serious flaws with not counting water as a renewable resource.

I've often found myself pointing this out to people when talking about water being used, though it does depend a lot on where the water comes from, and / or being diverted away from.

It's relevant inasmuch as the transport and purification of water can have a substantial energy cost (and things like _groundwater_ are being depleted faster than used - some of California is sinking, and the Ogalalla (while huge and still mostly there) would take 6,000 years to replenish if depleted

https://en.wikipedia.org/wiki/Ogallala_Aquifer

I'm curious how you think I found the 20,000 figure buried in a table ~20 pages in without reading it :)

I'm sure there is room for improvement in the methodology. There almost always is. You can contact the first author here [1] and I am sure, as a scientist, she would appreciate your correspondence.

[1]: https://www.dtu.dk/english/service/phonebook/person?id=80447

Thanks, I appreciate that you didn't just flippantly post this. However, I would say that citing the most extreme figure there without context is a technique of persuasion that pollutes discussion with hyperbole. I saw that number and it seemed immediately fishy. I still think so, but I won't get into all the reasons here because I don't have time. I really hate plastic bags. I've picked up hundreds of them off beaches worldwide. So we need to ban them and find an alternative--hey, like paper. Your comment inadvertently raised my hackles because it sounds a lot like you'd rather have BAU and plastic everywhere. (I hope not).

I hate litter, but I don't see much difference between something biodegrading over tens of years or never. Given all of the advantages plastic has over everything else, I would much rather we used that. We could penalise people who improperly dispose of waste - this seems to work quite well in Singapore.

Paper is a particularly bad replacement as it falls apart when wet - a couple of days ago a paper bag did this to me as I walked back in light rain. Additionally, paper necessarily has a higher environmental cost due to the weight and packing fraction of the raw materials.

I shared that number because it shocked me and the report looked authoritative. Thanks for helping to add context to it :)