Obama to create 17,000 green jobs. What's a green job?

President Obama announced $2.3 billion in federal tax credits on Friday, which he said would create 17,000 new "green" jobs.

Which is great, except that no one can count green jobs because, fundamentally, no one knows what a green job is.

I know, it should be obvious. Green workers are people who make solar panels, install insulation, run recycling programs, and similarly environmentally helpful things. But it quickly gets more complex that that.

Are all workers at an automaker green if a few of them make hybrid cars? Does the janitor's position at a wind-turbine factory count as a green job? What about the urban planner who designs a mass transit system one year and a strip mall the next?

For political reasons, the administration will probably not worry about such statistical nuances. They'll simply count all the jobs created by the companies that receive federal green-energy grants.

Some groups have made valiant attempts to hack a better path through this data jungle. Back in June, the Pew Charitable Trusts counted 68,200 green businesses employing 770,000 workers in 2007 (the latest data available). And green employment during the previous decade grew at better than twice the pace of employment overall, the group found.

But does anybody really know?

Even the Bureau of Labor Statistics, which has been cogitating on the problem since last spring, hasn't made up its mind on how to count green jobs.

"There's alternative ways for doing that and we haven't yet finalized our methodology," says John Galvin, associate commissioner for employment statistics at the BLS.

Just before Christmas, the agency got $7.8 million from Congress to resolve the problem. In the fourth quarter of this year, it plans to collect data from businesses and will provide its first report in the second half of 2011. The BLS will be the ultimate arbiter of who's a green worker and who isn't.

"We have to do it right," Mr. Galvin says. "We have to develop forms that are comprehensible to businesses ... We're still figuring out what we're going to ask them."

Until then, the number of green jobs in the United States is, well, whatever you want it to be.