A green job, also called a green-collar job is, according to the United Nations Environment Program, "work in agricultural, manufacturing, research and development (R&D), administrative, and service activities that contribute(s) substantially to preserving or restoring environmental quality. Specifically, but not exclusively, this includes jobs that help to protect ecosystems and biodiversity; reduce energy, materials, and water consumption through high efficiency strategies; de-carbonize the economy; and minimize or altogether avoid generation of all forms of waste and pollution."
A 2004 study by the Renewable and Appropriate Energy Laboratory (RAEL) at UC Berkeley reported that the renewable energy sector generates more jobs than the fossil fuel-based energy sector per unit of energy delivered (i.e., per average megawatt) across a broad range of scenarios. Contrarily, a report by Gabriel Calzada Alvarez analyzing the impact of an eleven-year Green energy project in Spain concluded that the U.S. should expect a loss of at least 2.2 jobs on average for each "green job" created, or about 9 jobs lost for every 4 created, in addition to those jobs that non-subsidized investments with the same resources would have created. A rebuttal to the Spanish study by the National Renewable Energy Laboratory (NREL) presented numerous allegations of methodological flaws in the Spanish study, citing outdated data, non-standard measures of job creation, and a lack of accompanying statistical analysis among the limitations of the study.