OLR Research Report

July 25, 2002





By: Kevin E. McCarthy, Principal Analyst

You asked for information on recently adopted California legislation (AB 1493) dealing with global warming. You were specifically interested in the genesis of this legislation and the issues that were raised in the debate on it.


The California legislature recently passed AB 1493, which requires the California Air Resources Board (CARB) to adopt regulations to reduce emissions of carbon dioxide and other greenhouse gases from vehicles in the state. The legislation arose from concerns that such emissions contribute to global warming. Proponents of the legislation argued that global warming could cause a wide range of adverse environmental and public health effects in the state, including more severe droughts, poorer air quality, and an increased incidence of respiratory disease. They also argued that these effects could harm several key industries in the state.

The key issues in the debate included the scope of the regulations, the role of the legislature in their adoption, and the relationship of the legislation to federal law that establishes fuel efficiency standards for vehicles. Opponents of the legislation argued that the legislation would grant CARB too much authority. They asserted that the legislation would allow CARB to adopt regulations that would bar the sale of certain types of vehicles, raise taxes, and restrict the number of vehicle miles traveled in the state. They also argued that the bill would, in effect, raise fuel efficiency standards for vehicles, an area that is governed by federal rather than state law.

The final version of AB 1493 addresses some of the concerns raised by the bill's opponents. It requires CARB to adopt regulations by January 1, 2003 that achieve the maximum feasible and cost–effective reductions in emissions of greenhouse gases from vehicles. The regulations are subject to legislative review. The regulations may not go into effect before January 1, 2006, and can only apply to 2009 and later model year vehicles. The regulations may not contain several types of measures, such as higher taxes or reduced speed limits. The bill and a summary prepared the Office of the Legislative Counsel are available at


As discussed in OLR memo 2002-R-0536, human activities, such as burning fossil fuels in transportation and power generation, have significantly increased the concentration of carbon dioxide and other greenhouse gases in the atmosphere. (Some of these gases are also produced by natural causes.) These gases trap heat in the atmosphere much like glass traps heat in a greenhouse. Environmentalists believe that increasing concentrations of greenhouse gases in the atmosphere will result in a wide range of harmful effects over the course of the 21st century. These include hotter summers, increased droughts, rising sea levels as polar ice caps shrink, impaired air quality, and increased rates of respiratory disease.

Although there is a growing consensus that global warming is a real and significant issue, there remain questions as to the speed at which the climate is changing, the effect of feedback mechanisms that may slow or speed climate change, and the impact of climate change on specific regions. There is also extensive debate on the appropriate policy response to these phenomena, in particular the role of regulatory versus non-regulatory approaches.


Global warming has been a major environmental issue in California for several years. Groups concerned with global warming have argued that it could cause several interrelated problems. For example, warmer temperatures throughout the year could produce extended droughts and increase the risk of catastrophic forest fires. Hotter temperatures in the summer could increase respiratory disease and mortality. In addition, proponents of global warming legislation argue that climate change may substantially harm key industries in the state, including agriculture, timber, and tourism. In recognition of the potential effects of climate change, the California legislature established the California Climate Action Registry in 2001, and required it to perform various functions relating to the provision of technical assistance for greenhouse gas emissions reductions. Among other things the registry must maintain a record of emission baselines and certify emission results.

Transportation has been a major focus of the debate on global warming in California. Transportation accounts for 59% of carbon dioxide emissions from fossil fuel combustion in the state, compared to 31% nationally. Because California is the largest market for automobiles in the country, its previous adoption of state-specific regulations on other types of emissions led automakers to build cars that meet California's standards and to sell them nationwide.

In February 2001, Assembly Member Fran Pavley introduced AB 1058. The bill, which was the predecessor to AB 1493, would have required CARB to adopt regulations by January 1, 2003, to achieve the maximum feasible and cost-effective reduction of greenhouse gases produced by vehicles. AB 1058 specified that the regulations could only apply to 2009 and subsequent model year vehicles. It contained some, but not all, of the other limitations subsequently placed on the regulations by AB 1493. The bill required CARB to report to the legislature and governor on the content of the regulations by January 1, 2005.

The bill was initially drafted by the Bluewater Network and supported by several dozen other environmental organizations, as well as the American Lung Association. It was opposed by the Alliance of Automobile Manufacturers, the state chamber of commerce, General Motors, and the Western States Petroleum Association. The Assembly and Senate passed different versions of AB 1058, and AB 1493 was introduced in 2002 as a parallel bill. The legislative histories of the bills are available on-line at


Among the key issues in the debate were the lack of specificity as to the types of measures that CARB could adopt and the legislature's role in making this determination. Opponents of AB 1058 argued that it could result in new taxes, fees for miles traveled, or the elimination of entire classes of vehicles, such as sports utility vehicles (SUVs). An analysis prepared by the staff of the Assembly's Transportation Committee noted that AB 1058

…gives scant guidance to [C] ARB as to how carbon dioxide is to be regulated, what means of emission reductions might be required, or what specific level of reduction should be sought. The sponsor maintains that this lack of detail will provide maximum flexibility for the creative development of practical and cost-effective methods of controlling carbon dioxide. Conversely, it affords the legislature no indication of, nor any control over, the scope or nature of any resulting program.

Several of these issues were addressed in AB 1493, as discussed below.

The bills' opponents also asserted that it would limit consumer choice. They argued that vehicle manufacturers would likely produce one set of vehicles that met the CARB regulations, while consumers in other states could buy a broader set of vehicles. In addition to restricting consumer choice, this could lead to higher costs for vehicles.

Another issue that arose was the relationship between the bills and federal law. Opponents of the bills argued that the federal corporate average fuel economy (CAFE) law prohibits state regulation of carbon dioxide emissions from vehicles. They based this argument on the theory that carbon dioxide regulation is tantamount to fuel economy regulation, preempted by CAFE.



AB 1493 makes eight findings. A key finding is that global warming would have “compelling and extraordinary” impacts on California, including (1) potential reductions in the state's water supply, (2) adverse health impacts due to the increase in air pollution brought about by higher temperatures, (3) a potential doubling of the number of catastrophic wildfires due to dryer vegetation, and (4) significant impacts to consumers due to higher costs of food, water, and energy, among other things. The legislature also found that that (1) passenger vehicles and light duty trucks account for 40% of the total greenhouse gas emissions in the state and (2) technological solutions to reduce these emissions will stimulate the state's economy and provide enhanced job opportunities.

Development and Review of the CARB Regulations

The bill requires CARB to develop its regulations by January 1, 2005 (compared to January 1, 2003 in AB 1058). The bill states that this delay is intended to give the legislature time to review the regulations, and to determine whether additional legislation is needed before they go into effect. The bill establishes criteria for determining whether a measure is feasible and cost-effective.

The bill requires CARB to consider several factors in developing the regulations, including their technical feasibility and their impact on the state's economy. It requires that the regulations provide (1) the maximum feasible flexibility to entities subject to them, including permitting alternative compliance methods and (2) emissions credits for reductions they make before the effective date of the regulations.

CARB must send the regulations to the relevant legislative committees for review within ten days of their adoption. The legislature must hold at least one public hearing on the regulations and can modify them.

Restrictions on the Regulations

The bill bars the regulations from (1) imposing any additional fees or taxes; (2) banning the sale of any specific types of vehicle, including SUVs; (3) requiring a reduction in vehicle weight; (4) reducing speed limits; or (5) limiting vehicle miles traveled. The alternative compliance methods cannot require mandatory trip reductions or land use restrictions.