production occur in two separate sets of industries that are only related through intra-industry linkages such as the purchase of capital assets. These findings have implications for taxing polluting agencies and subsidizing green outputs.

However, the output approach is less useful for informing skills policy. On the one hand, it leaves out jobs in firms that produce non-green outputs but implement green technologies. For example, a leather manufacturing firm may implement technologies to clean wastewater and may employ workers in charge of this process. On the other hand, it includes all jobs regardless of whether they involve green tasks. For example, it would include the receptionist at a firm producing a filter to purify air. This issue cannot be solved by just restricting the count to production workers since not every worker involved in the production of a green output will perform green tasks or require green skills. For example, while an engineer designing an electric car may require energy efficiency knowledge, most assemblers of such cars may perform the same tasks as assemblers of gas-powered cars.

Moreover, to inform skills policy it is crucial to profile occupations, which reveals an additional limitation of the output approach for this policy objective. Most notably, surveys that are designed to measure green jobs based on their output (or the data that aligns well with this approach) do not collect or link occupational data. Occupational data is necessary to understand the task content and skills requirements of such jobs.<sup>21</sup> In the best-case scenario, analysts would need to work with multiple surveys or databases to adequately inform skills policy.

The U.S., Canada, and the E.U. have good applications of the output approach. In 2011, the U.S. Bureau of Labor Statistics conducted the Green Goods and Services (GGS) survey.<sup>22</sup> The GGS survey was a firmlevel survey on a sample of 120,000 establishments in industries identified as potentially producing green outputs—333 industries out of 1,200 detailed at the six-digit American Industrial Classification System (NAICS). The selected industries represent 23 percent of all establishments and 20 percent of employment in the U.S. economy. Specifically, the GGS survey asks establishments for the percentage of revenues (or, for firms that do not generate revenue, the percentage of employment) deriving from green outputs according to the BLS definition. This self-reported percentage was then decoded into an establishment’s green percentage. Most sampled establishments ended up not having revenues or employment associated with a green output (confirming limitations of relying solely on standard classifications), only around 2 percent of the U.S. workforce was estimated to do so.<sup>23</sup> Lastly, replicating a survey like the GGS in developing countries would represent a costly endeavor, not only in terms of sampling a substantial number of firms to have statistical power but also in explaining sophisticated questions to respondents.

The BLS could overcome the critical limitation mentioned above regarding occupational information by linking the GGS survey to the Occupational Employment Survey (OES), a well-established survey designed to produce employment and wage estimates for nearly 800 narrowly defined occupations

> 21 To the best of our knowledge, the U.S. is only country that collects data on green outputs and links it to occupational data.

> 22 BLS (2013a), BLS (2013b), and BLS (2012a).

> 23 BLS (2013a).

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