Green jobs accounted for 2.4 percent of the nation’s total employment in 2010, the Labor Department reported Thursday in its first-ever survey of green goods and services jobs.

According to the report, which gave a snapshot of the role the green environmental sector plays in the U.S. economy, the United States had 3.1 million green jobs in 2010, the vast majority of them in the private sector. The public sector listed 860,000 green jobs, the report said.

Jonathan Rothwell, a senior research analyst at Brookings Institution, warns that the report should not be used as a barometer to measure whether President Obama’s efforts at boosting the number of green jobs have been a success.

“It would be very hard to draw conclusions about the impact of recent public policies on job creation,” Rothwell said. The report does not contain any growth figures, meaning that it doesn’t reflect how the number of jobs may have changed over time. And even if such numbers were available, Rothwell said, it would be difficult to draw a direct cause-and-effect relationship between policies and numerical shifts.

The manufacturing sector accounted for the greatest number of green jobs among any private-sector industry, a promising sign for a strategically important sector, analysts said.

There are “a lot of export opportunities for America if we can take leadership in this sector,” said Cai Steger, energy policy analyst with the National Resources Defense Council advocacy group.

Other areas that accounted for large portions of the nation’s green jobs included construction (372,100 jobs) and professional, scientific and technical services (349,000 jobs).

The report also examined the picture at a state-by-state level. California had 340,000 green jobs in 2010 -- more than in any other state and the District of Columbia -- making up 2.3 percent of total employment.

The District, with 26,941 jobs in the green goods and services sector, was near the top of the list of the proportion of jobs in relation to total employment, at 3.9 percent.

Rothwell said the government’s findings are similar to those of other recent reports on green jobs. This consistency, he says, shows that “despite all of the contention about what a green job is and whether this or that should be counted as a green jobs, there is a consensus emerging” as to how to study and track this sector.

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