This is doubly false. First, offshore jobs has not led to high unemployment in the US; 2 million jobs were offshored between 1994 and 2007 even as the unemployment rate dropped from 6.6% to 4.4%[1][2] - apparently most of those people found other work. Secondly, the reduced emissions is not caused by offshored jobs, either; US manufacturing output is up this year[3] even as emissions have dropped 8%. Not that a cleaner China wouldn't be even better.

[1]http://www.trivisonno.com/offshoring [2]http://data.bls.gov/timeseries/LNS14000000 [3]http://www.federalreserve.gov/releases/g17/current/