You want to build a widget in a factory. The factory consumes 1 MW of power to operate and emits 5 kg per hour of pollutants into the air as a byproduct of widget production.

If the work the factory does is outsourced to China, the widgets don't necessarily cost less energy or emissions to produce. So you've just shifted emissions from one country to another — it's an accounting trick, not a genuine reduction.

seems pretty clear to me: you used to manufacture X in the US, now you import X from the US. The pollution that X used to generate in the US is off the US's emissions sheet.

If you buy goods instead of producing them, the emissions are shifted largely to the producing country.

It s therefore important to look at the footprint of imported and exported goods.

I assume he means exporting manufacturing and other "dirty" industries. IE, we import rare earth based products from China because they can mine them so cheaply, at least partially because they don't have the same concern for environmental impact of the mining.

Sounds like they are tacitly advocating repatriating manufacturing to cleaner energy countries and putting pollution tariffs on products based on how dirty or clean they were manufactured...

My guess is the OC is alluding to the large amount of manufacturing that happens in China. If that were to occur in the US then the pollution would happen here.