‘Green collar’ jobs seen as prosperous
By 2030, nearly a half-million new jobs could be created in green industries from MSNBC

Green-Collar Jobs for Urban America from AlterNet

Earliest reference to Green Collar Worke we’ve found so far:
1976, Patrick Heffernan, “Jobs for the Environment — The Coming Green Collar Revolution”, in Jobs and Prices in the West Coast Region: Hearing before the Joint Economic Committee, Congress of the United States, Ninety-Fourth Congress, Second Session, U.S. Government Printing Office, page 134,

Wiktionary Definition:
http://en.wiktionary.org/wiki/green-collar