A number of congressional proposals to advance programs designed to reduce greenhouse gases have been introduced in the 110 th Congress. The second is to enact a market-oriented greenhouse gas reduction program along the lines of the trading provisions of the current acid rain reduction program established by the 1990 Clean Air Act Amendments. The major provisions of the seven Senate bills are compared in Appendix A . As introduced, the cap is estimated by the sponsors to reduce emissions to 15% below 2005 levels in 2020, declining steadily to 63% below 2005 levels in 2050. S. 3036 , introduced by Senator Boxer on May 20, 2008, is identical to the reported version of S. 2191 , except that S. 3036 contains a budget amendment aimed at making the bill revenue-neutral. This bill was considered by the Senate the week of June 2, 2008. S. 280 , introduced January 12, 2007, by Senator Lieberman, would cap emissions of the six greenhouse gases specified in the United Nations Framework Convention on Climate Change at reduced levels from the electric generation, transportation, industrial, and commercial sectors—sectors that account for about 85% of U.S. greenhouse gas emissions. The bill also contains an extensive new infrastructure to encourage innovation and new technologies. Beginning in 2020, the country's emissions would be capped at their 1990 levels, and then proceed to decline steadily until they were reduced to 20% of their 1990 levels in the year 2050. The bill would establish a renewable portfolio standard (RPS) and a new low-carbon generation requirement and trading program. Beginning in 2012, covered entities would have emissions targets set at their 2006 levels in 2020. H.R. Using the same basic structure as S. 280 , the emission caps under H.R. Although H.R. H.R. H.R. H.R. 620 . Using the same basic structure as H.R. H.R. H.R. The bill would direct EPA to develop emission performance standards for non-covered entities, which may include coal mines, landfills, wastewater treatment operations, and animal feeding operations. H.R. H.R. Legislative Action in the 110th Congress

On May 20, 2008, the Senate Committee on Environment and Public Works' Subcommittee on Private Sector and Consumer Solutions to Global Warming and Wildlife Protection reported out a revised version of S. 2191 . As ordered reported, S. 2191 's emissions cap is estimated by its sponsors to require a 71% reduction from 2005 levels by 2050 from covered entities (estimated by the sponsors to account for 87% of total U.S. greenhouse gas emissions). Comparison of Key Provisions of House Greenhouse Gas Reduction Bills
Appendix C. Common Terms
Allocation schemes (upstream and downstream). Cap-and-trade program. In contrast to a cap-and-trade program, in which the quantity of emissions is limited and the price is determined by an allowance marketplace, with a carbon tax, the price is limited and the quantity of emissions is determined by the participants based on the cost of control versus the cost of the tax. Emissions cap. Generally a greenhouse gas reduction program that allows emitters to choose between complying with the reduction requirement of a cap-and-trade program or paying a set price (safety valve price) to the government in lieu of making reductions.
Multiple proposals to advance programs that reduce greenhouse gases have been introduced in the 110th Congress. S. 2191 was reported May 20, 2008, from the Senate Committee on Environment and Public Works. An amended version of S. 2191 S. 3036, was considered by the Senate in June 2008, but a vote to invoke cloture failed. In general, these proposals would create market-based greenhouse gas reduction programs along the lines of the trading provisions of the current acid rain reduction program established by the 1990 Clean Air Act Amendments. This report presents a side-by-side comparison of the major provisions of those bills and includes a glossary of common terms (Appendix C).
Although the purpose of these bills is to reduce greenhouse gases (GHGs), the specifics of each differ greatly. Five bills (S. 280, S. 309, S. 485, H.R. 620 and H.R. 1590) cap greenhouse gas emissions from covered entities at 1990 levels in the year 2020. S. 317 places its first emissions cap at 2001 levels in 2015; S. 1766 targets reductions at 2006 levels in 2020; S. 2191 as reported would cap GHGs at about 19% below 2005 levels in 2020; H.R. 4226 would limit 2020 emissions to 85% of their 2006 levels; H.R. 6186 would reduce emissions to 20% below 2005 levels by 2020, and H.R. 6316 would reduce emission to 20% below 1990 levels by 2020. Ten bills (S. 280, S. 317, S. 485, S. 2191, S. 3036, H.R. 620, H.R. 1590, H.R. 4226, H.R. 6186, and H.R. 6316) would establish cap-and-trade systems to implement their emission caps. In contrast, S. 1766 provides for two compliance systems—a cap-and-trade program and an alternative safety valve payment—and allows the covered entities to choose one or employ a combination of both. Finally, S. 309 provides discretionary authority to the Environmental Protection Agency (EPA) to establish a cap-and-trade program to implement its emission cap.
The differences continue with respect to entities covered under the programs. Three bills (S. 309, S. 485, H.R. 1590) provide discretionary authority to EPA to determine covered entities by applying cost-effective criteria to reduction options. In contrast, S. 317's emission cap is imposed solely on the electric generating sector. The other bills (S. 280, S. 1766, S. 2191, S. 3036, H.R. 620, H.R. 4226, H.R. 6186, and H.R. 6316) cover most economic sectors but not all (e.g., they exclude the agricultural sector). Thus, the overall reductions achieved by the bills depend partly on the breadth of entities covered.
Beyond the basics of these bills, each contains other important provisions. For example, S. 280 creates a new innovation infrastructure, while several—S. 1766, S. 2191, S. 3036, H.R. 4226, H.R. 6186, and H.R. 6316—encourage foreign countries to undertake comparable control actions and specify potential consequences for inaction. Other provisions include mandatory greenhouse gas standards for vehicles (S. 309, S. 485, H.R. 1590), and a renewable portfolio standard for the electric generating sector (S. 309, S. 485, H.R. 1590). This comparison should be considered a guide to the basic provisions contained in each bill. It is not a substitute for careful examination of each bill's language and provisions.