California’s unemployment rate has hovered around 12.4 percent for almost a year. But a new report released late Tuesday shows that green jobs continued to grow amid the downturn.

California’s “Core Green Economy” had 174,000 jobs in January 2009, up from 169,000 in January 2008, according to the report by Next 10, a nonpartisan think tank founded by philanthropist and venture capitalist Noel Perry.

The Bay Area — a hub for solar manufacturing and other clean energy generation — continued to post the state’s strongest green employment gains, adding 2,500 jobs — half of the 5,000 statewide — during the January 2008 to January 2009 time frame.

The bulk of the state’s green jobs are in services, such as environmental consulting and green marketing. But manufacturing represents 26 percent of all green employment — a significant share, given that manufacturing represents just 11 percent of the state’s total economy.

The report, called “Many Shades of Green: Regional Distribution and Trends in California’s Green Economy,” is the second annual report for Next 10 prepared by Collaborative Economics of Mountain View.

The report’s authors point to California’s long history of forward-thinking public policy as driving much of the state’s green job growth.

“We’ve had a renewable portfolio standard for utilities and energy efficiency requirements for buildings for years,” said Perry, who started Next 10 in 2003. “The bar has been raised here in California, and entrepreneurs and innovators are trying to reach that bar.”

Job growth in the Bay Area can be found across cleantech sectors, particularly energy generation, carbon emissions monitoring, clean transportation and energy storage.

Picarro, a Sunnyvale company that makes scientific instruments to measure greenhouse gases such as carbon dioxide and methane, had fewer than 50 employees last year. The headcount is now 70, and the company expects to have well more than 100 by this time next year. Palo Alto’s Tesla Motors, which had about 500 employees a year ago, has well more than 800 today.

“There’s a lot of excitement about energy storage,” said Doug Henton of Collaborative Economics. “It’s the holy grail. Everyone is trying to figure out how to develop advanced batteries and fuel cells.”

Tracking green job growth can be difficult because there are several different ways to define “green jobs” and the “green economy.” Collaborative Economics defines green jobs and businesses as those that conserve energy and natural resources, reduce pollution, repurpose waste and provide alternatives to carbon-based energy sources. The firm scoured employment databases and then reached out to individual companies in an effort to quantify the actual number of jobs created.

Contact Dana Hull at 408-920-2706.