With its legal mandate to reduce greenhouse gas emissions approximately 30% by 2020, California leads the nation in plans to combat climate change. But unlike Gov. Schwarzenegger and Al Gore, not everyone thinks reaching 80% of current emissions levels in 11 years is a plausible target.

At a U.S. Fish and Wildlife Service conference this week in San Francisco, Stanford professor Stephen Schneider called the 2020 target “an impossible dream” and argued that setting unrealistic targets such as this one could ultimately hurt the emissions reduction process by reducing credibility, and perhaps, momentum.

Schneider, a member of the U.N.’s Intergovernmental Panel on Climate Change (IPCC) and a senior fellow at Stanford’s Woods Institute for the Environment, said that instead of focusing on specific percentages, policymakers should be focused on investing in the right technologies so that by 2020, our economy will be ready and able to handle a sustainable, long-term reduction in emissions.

“We need to get off the numbers and get on (the) investments,” said Schneider. “We’re not going to be credible if we get focused on something that can’t happen.”

Proponents of AB 32, like Google CEO Eric Schmidt, argue that the goals set by California’s 2006 Global Warming Solutions Act (AB 32) will foster clean energy technology–the type of investment that Schneider advocates. No one denies that reaching the 2020 target will be a challenge. And earlier this month California Air Resources Board Chair Mary Nichols seemed to echo Schneider’s sentiments when she told VerdeXchange News that rather than using the AB 32 as a “counting game,” the the goal “is to achieve real transformation in our energy economy.” She cited the requirement that the law be updated every five years, thus leaving room for a mid-course correction down the road.

Read the full Nichols interview here.