1. The environmental costs are enormous just in the shipping.
They're really not.
Shipping is unbelievably inexpensive. Most of the cost is fuel. Therefore, shipping uses unbelievably small amounts of fuel.
It's far less environmentally damaging to ship a container of cargo from China to an Amazon warehouse in the US, than it is to deliver that cargo from Amazon's warehouse to the end customers.
When you consider that the manufacturing workers in China travel to work by bicycle or public transport, and that if the goods were made by Americans, the workers would commute by car, it's almost certainly better for the environment to make stuff in China and ship it across the Pacific.
Costs are generally an excellent proxy for environmental damage (and certainly a FAR better proxy than mere distance). That long distance transport of goods is bad for the planet is one of those ideas that is obvious, simple, reasonable, and completely wrong. If it's cheaper to ship stuff around the world, it's probably also better for the environment.