I'm not so sure about that. Assuming that the pollution due to shipping is mostly by burning fuels, "low cost of shipping" actually puts an upper bound on the

I'm not so sure about that. Assuming that the pollution due to shipping is mostly by burning fuels, "low cost of shipping" actually puts an upper bound on the amount of pollution, because shipping companies can burn only so much fuel while staying profitable. Once there was a popular meme saying shipping CFLs from China generates more pollution than the amount reduced by changing incandescent bulbs to CFLs. Of course, when you consider how much coal you can burn for the shipping cost, the argument falls down quickly.