SACRAMENTO -- After warnings of rampant fraud and abuse, California's Attorney General Jerry Brown is calling on the feds to regulate the unwieldy frontier of retail carbon offset sales.

The national market for carbon offsets is expected to reach $100 million within the next four years -- with an estimated 80 percent of the offset market going to companies attempting to reduce their carbon footprint.

The market is rife with problems.

There are no government standards for quantifying emissions from offset projects, there are no guarantees that a company isn't double-selling their credits or claiming credits for practices that are already required by law. Adding to the potential for fraud, most of the organizations that purchase the credits have little understanding of the process.

"It's important for consumers to know exactly what they are getting," Gareth Lacy, Brown's spokesman told LNL. "Carbon offsets are an important tool."

As green businesses become more popular, so do carbon offsets.

The credits are marketed to those who hope to zero-out their carbon emissions. An individual may buy credits to offset travel for a business trip or vacation. A company may buy offsets to claim their business is "carbon neutral."

The offsets act like shares in a company that undertakes projects like reforestation or building renewable energy projects. A single, working individual who puts 7.53 tons of carbon dioxide into the atmosphere a year may offset that impact by buying $113-worth of carbon credits, whereas a large corporation may spend millions.

"The Federal Trade Commission must set clear guidelines for the sale of carbon offset credits," Brown said in a recent statement. "As more Americans try to offset their carbon emissions, the danger grows that some individuals will attempt to manipulate the system. Consumers must feel confident that they actually get what they pay for-real carbon reduction offsets."

But absent a national system, a successful voluntary system is taking shape in California.

The California Climate Action Registry counts 332 of the state's largest corporations and public agencies as its members. First created by legislation in 2001, the registry was formed by a group of CEOs to voluntarily report their greenhouse gas emissions.

On Tuesday, the Los Angeles-based organization created a stringent set of protocols regulating offsets.

The registry just certified its first forest renewal project last month and one of California's three investor-owned utilities, Pacific Gas and Electric (PG&E), recently purchased $2 million in carbon offsets, some of which were derived from the project.

The two forest projects are the 24,000-acre Garcia River Forest in Mendocino County, owned and managed by The Conservation Fund and the 2,100-acre Van Eck Forest in Humboldt County, managed by Pacific Forest Trust.

Both projects follow the registry's "forest protocols" whose requirements include a permanent conservation easement be placed on the forest, third party verification and sustainable management techniques that go above "business as usual."

According to the registry, California's foresting laws are some of the strictest in the world.

"These two forest projects clearly demonstrate that (the registry's) forestry protocols can be used in the fight against global warming," said Gary Gero, the interim president of the California Climate Action Registry.

Later this year, Congress is expected to debate legislation under which businesses and other organizations would likely be "credited" for offsetting their carbon emissions.

The FTC has yet to respond to Brown's request.