Gore’s call for 100 percent renewable electricity generation within 10 years may seem, at first blush, to be so far out in left field as to lack any seriousness — but it has some commonality with established regulatory policy. For example, California’s global warming law (AB 32) is rooted in Governor Schwarzenegger’s Executive Order S-03-05, issued on June 1, 2005, ordering that “the following greenhouse gas emission reduction targets are hereby established for California: by 2010, reduce GHG emissions to 2000 levels; by 2020, reduce GHG emissions to 1990 levels; by 2050, reduce GHG emissions to 80 percent below 1990 levels.”

What is notable about both Gore’s and the governor’s targets is that all the numbers happen to end in zero. Gore did not call for a reduction of, say, 95 percent in 13 years; his targets are evidently ballpark numbers more-or-less picked out of a hat. “One hundred percent” can basically be interpreted to mean “a whole lot” and “10 years” translates to “ASAP.”

Likewise, the governor’s targets for California are a little bit fuzzy. The 2010 target was apparently over-ambitious; and although the 2020 target has been legislatively mandated in AB 32, a careful reading of the statute reveals that its “rock-solid” cap is actually a little bit squishy. The legislation authorizes the governor to suspend the regulations under the threat of “significant economic harm.” On the other hand, the legislature also clearly anticipated possible reductions below the 2020 limit, because it stipulated an additional requirement that the regulations achieve the “maximum technologically feasible and cost-effective greenhouse gas emission reductions.”

The requirement for maximum emission reductions could be the key to achieving something like what Gore has in mind, in that it represents an explicit authorization for over-compliance incentives. This differs from the “maximum cost reductions” objective of conventional cap-and-trade systems, and is better addressed by something like a carbon tax — Gore’s policy instrument of choice.

A carbon tax lacks the “environmental certainty” of cap-and-trade. However, taxes and caps are neither mutually exclusive nor incompatible policy options, and a tax would actually provide greater certainty of achieving emission goals if it is implemented as a price floor [PDF] in the context of cap-and-trade.

Any serious proposal relating to climate policy must be backed up by concrete regulatory action, and to this end the California Air Resources Board is inviting the public and stakeholders to comment on its recently-released Draft AB 32 Scoping Plan document. (Comments are requested by August 1, but will be accepted until August 11.)