The Financial Times reports:

Emissions of greenhouse gases from the US fell for the first time in
more than a decade between 2000 and 2003 following a shift in heavy
manufacturing away from US shores to cheaper locations such as China.

[snip]

The slight fall had come even as the US population grew by 8.6m, and
increased its gross domestic product by the worth of the economy of
China, Mr Connaughton said.