The ridiculous "43 times" number was only obtained when considering "all environmental factors", not just energy use/climate change. The methodology chosen required offsetting the worst individual factor compared to conventional LDPE bags (pp. 80). For paper bags, this was "Freshwater eutrophication" (pp. 119). So this ridiculous number is only a) due to questionable methodology used in this study (clearly chosen to give plastic bags an unrealistic environmental performance), and b) because plastic production has negligible impact on nutrient content of lakes compared to forestry.

The study seems to have altogether omitted to consider the impact of persistent plastic pollution on the marine environment. This is where recyclable/biodegradable materials, like paper, really do shine compared to nonbiodegradable and hard-to-recycle (TFA) plastic.