Chine is the biggest climate polluter in absolute terms; but per capita, the US and Australia are way ahead, so maybe you should include them in your list of likely candidates.
A lot of my goods come from basically slave labor and polluters. They have a competitive advantage over companies who don't, so garbage floats and takes over. Countries are complicit when they support or benefit from other countries which do this.
This is exactly the sort of thing where we're all in it, hands dirtied, want it or not.