I guess the birds getting killed by plastic bags in the environment and the sea are happy to know that the life cycle energy consumption is better than paper.
That said I do not use paper bags or plastic bags but a recycled canvas bag I've used for hundreds of shopping trips.
Good to hear it. You're probably close to breaking even on the environmental cost it took to make that canvas bag.
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The more energy it takes to make something, the greater the potential environmental impact.
Plastic in the ocean is awful. The vast majority of it comes from just a few countries. What some westerner uses to take home their groceries isn't even a rounding error in terms of source waste.
Reading the report says "Low-residual-value plastic waste is more likely to leak than high-value plastic [...] his means that products or packaging with low residual value (plastic shopping bags, for instance) are less likely to be collected; they therefore become a particularly significant contributor to ocean plastic"
Please also note that the biggest contributor, and the biggest reason for China being that contributor, is simple lack of a functional garbage collection system at all in large parts of the country.
I emphasize this because I think people tend to focus on the minutiae (ie, paper, plastic or canvas when it comes to grocery bags) when the bulk of the problem has nothing to do with bag choice, it has to due to a complete lack of wastestream infrastructure. It is understandable to a degree. The problem is so overwhelming, it feels like what one person can do is never going to be enough.
That said I do not use paper bags or plastic bags but a recycled canvas bag I've used for hundreds of shopping trips.