California and the nation may be taking two steps forward and one step back when it comes to their effort to cut greenhouse gases from cars through a mileage standard approach, an economist told the California Air Resources Board April 20. While the so-called corporate average fuel economy approach incentivizes smaller vehicles and new automotive technologies--like hybrid drive trains--the resulting boost in mileage just gives people an incentive to drive more, according to Soren Anderson, Haas Energy Institute economist. A fuel tax would be superior in cutting greenhouse gas emissions from cars because, according to Anderson, it would not only increase energy efficient cars, but also decrease driving. Anderson pointed to research showing that a 10 percent increase in the price of gasoline almost immediately reduces gas consumption by 5 percent because people drive less to save money. Yet, despite the potential effectiveness of a tax, Anderson admits that it\u2019s a political non-starter. So his prescription is to keep broadening and tightening mileage standards, while continuing to talk about a gas tax. The transportation sector produces the most greenhouse gas emissions in the state, followed by the energy sector. * * * * * The U.S. Supreme Court is nearing a decision on whether California and other states can sue power plant operators to cut their greenhouse gas emissions under federal common law on grounds they constitute a public nuisance. The court heard oral arguments April 20 in the case, American Electric Power Company, Inc., et al. v. Connecticut, et al. California is a party to the lawsuit. Justices expressed some skepticism about whether the judiciary could adequately devise a remedy in the case, citing the complicated nature of the climate change problem, suggesting it might better be left to Congress and the federal Environmental Protection Agency. The case stems from an action states brought against five utilities that operate coal power plants. In that litigation, the states asked a federal judge to cap utility carbon dioxide emissions. The utilities claimed the states did not have standing to file the suit--a contention with which the trial court agreed. The states then appealed to the U.S. Court of Appeals for the Second Circuit. That court ruled states could press their suits. It subsequently turned down an appeal by utilities for a rehearing. The utilities then appealed to the High Court. In accepting the case for review, the Supreme Court said it would decide whether states have standing to sue for greenhouse gas caps, whether federal common law provides a cause of action in the absence of any federal greenhouse gas statute, and whether a court can determine a \u201creasonable\u201d cap on emissions based on \u201cjudicially discoverable and manageable standards\u201d or whether it requires \u201cinitial policy determination[s]\u201d to settle the matter. * * * * * Greenhouse gas emissions dropped 6 percent in the U.S in 2009, the U.S. Environmental Protection Agency announced April 19. Carbon gases, generated principally by the electricity sector and transportation, were 6,633.2 million metric tons. Between 1990-2007 greenhouse gas levels rose 7.3 percent, but the 2009 levels were 427.9 million metric tons lower than 2008 emissions, according to the 2011 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2009. \u201cThe U.S. still has a ways to go to get to 1990 [emission] levels as does California,\u201d said California Air Resources Board spokesperson Gennet Paauwe. The Air Board hopes to complete its 2009 greenhouse gas inventory for California this summer. \u201cCalifornia\u2019s inventory may differ from the nationwide inventory, since our emission profile differs--particularly with respect to the fuel we use to generate electricity,\u201d Paauwe added, noting the state uses far less coal than other parts of the country. EPA attributed the drop to lower economic output, lower natural gas prices, and less carbon-intense fuels. In 1990, the electricity sector emitted 1,821 million metric tons of carbon dioxide equivalent. That rose to 2,413 million metric tons in 2007, then by 2009 fell to 2,159 million metric tons. At the same time, emissions of methane--a greenhouse gas 20 times more potent than carbon dioxide--increased by 1.7 percent since 1990. The cause, according to EPA, was a rise in natural gas use and gas released from livestock and landfill wastes. Industry electrical use caused about 26 percent of the measured emissions, followed by residential and commercial sectors. The residential and commercial power users accounted for 22 and 19 percent, respectively, of carbon emission in 2009. Emissions from these end-use sectors have increased 25 percent since 1990, according to EPA\u2019s greenhouse gas emission inventory.