As Congress continues the debate on an appropriate response to the climate change issue, multiple bills have been introduced to begin reducing greenhouse gas (GHG) emissions. Of these, S. 2191 (the Lieberman-Warner Climate Security Act of 2008 ) has received particular attention. Introduced by Senator Lieberman, S. 2191 was ordered reported by the Senate Committee on Environment and Public Works on December 5, 2007. Numerous analyses have been done on its impacts, and as of April 2008, six studies had been released. The most comprehensive analysis has been conducted by the U.S. Environmental Protection Agency (EPA). The report is entitled: EPA Analysis of the Lieberman-Warner Climate Security Act of 2008: S. 2191 in 110 th Congress (March 14, 2008). The analysis employs a suite of models and basecases, along with some useful sensitivity analyses. This report will focus on three of the models, two basecases, and sensitivity analysis as appropriate. The first model is ADAGE: a computable general equilibrium (CGE) model developed by RTI International. The case employing the reference basecase is designated EPA/ADAGE-REF in this report, while the case employing the high technology basecase is designated EPA/ADAGE-TECH. The second model is IGEM: a CGE model developed by Dale Jorgenson Associates. The case employing the reference basecase is designated EPA/IGEM-REF in this report, while the case employing the high technology basecase is designated EPA/IGEM-TECH. The third model is IPM: a dynamic, deterministic linear programming model of the U.S. electric power sector developed by ICF Resources. The case employing the IPM model is designated EPA/IPM in this report. A second analysis has been conducted by the Energy Information Administration (EIA). The report is entitled Energy Market and Economic Impacts of S. 2191 , the Lieberman-Warner Climate Security Act of 2007 (April 2008). The analysis employs EIA's NEMS model: a macroeconomic forecasting model with extensive energy technology detail. In addition to conducting a "core" analysis of S. 2191 using its preliminary 2008 Annual Energy Outlook (AEO) Baseline , EIA also conducts some useful sensitivity analyses that focus on the upside risk of increased energy prices under S. 2191 which are discussed as appropriate. The core S. 2191 analysis is designated EIA/NEMS in this report. A third analysis has been conducted by the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change. The report is an appendix to a more comprehensive analysis of cap-and-trade programs released in 2007. The appendix is titled: Appendix D: Analysis of the Cap and Trade Features of the Lieberman-Warner Climate Security Act ( S. 2191 ) . The appendix employs MIT's EPPA CGE model and presents some useful sensitivity analyses of S. 2191 's offset and carbon capture and storage (CCS) bonus allowance provisions. The case that includes S. 2191 's 15% international offset and CCS subsidies provisions is designated MIT/EPPA in this report. A fourth analysis has been conducted for the Clean Air Task Force (CATF) by OnLocation. The report is titled The Lieberman-Warner Climate Security Act— S. 2191 : A Summary of Modeling Results from the National Energy Modeling System (February 2008). Employing EIA's NEMS model, the CATF analysis is designated CATF/NEMS in this report. A fifth analysis has been conducted for the American Council for Capital Formation (ACCF) and National Association of Manufacturers (NAM) by Science Applications International Corporation. The report is entitled Analysis of The Lieberman-Warner Climate Sec urity Act ( S. 2191 ) Using The National Energy Modeling System (NEMS) . Employing NEMS, ACCF/NAM employs two basic cases: (1) a high cost case using the most constrained and high cost assumptions of any of the analyses presented here (designated as ACCF/NAM/NEMS-HIGH) and (2) a low cost case using the second most constrained and high cost assumptions of any of the analyses presented here (designated as ACCF/NAM/NEMS-LOW). A sixth analysis has been conducted for the National Mining Association (NMA) by CRA International. The report is entitled Economic Analysis of the Lieberman-Warner Climate Security Act of 2007 Using CRA ' s MRN-NEEM Model (April 8, 2008). The analysis employs CRA's MRN-NEEM macroeconomic model with extensive electric power sector detail. The case employing the NMA analysis is designated NMA/CRA. It should be noted that several of the studies examined in this report are published as presentations with limited documentation, making comparative analysis difficult. Each presentation has selected features or impacts it is particularly interested in highlighting. The more comprehensive analyses are the work by EPA, EIA, and MIT. In order to increase the comparability of the various cases examined here, CRS has converted all publicly available data presented by the cases to 2005 dollars (where appropriate) and interpolated missing data where possible. Likewise, where studies have stated they used specific projections as a base case (such as EIA ' s Annual Energy Outlook 2007 or preliminary 2008 projections), CRS has assumed those assumptions have not been altered except as specifically stated by the study. This analysis considers the bill as ordered reported by the Senate Committee on Environment and Public Works, incorporating the proposed deficit reduction amendment— S. 3036 is identical to that version, including the deficit amendment. Other proposed amendments are likely if the bill moves to the floor, and these amendments, if adopted, could affect the costs and benefits of the overall bill. S. 2191 , The Lieberman-Warner Climate Security Act of 2008, was introduced October 18, 2007, by Senator Lieberman. On December 5, 2007, the Senate Committee on Environment and Public Works ordered reported an amended version of the bill that would establish a mandatory cap-and-trade system to reduce greenhouse gas emissions from most sectors of the economy. 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). Overall, the sponsors estimate that S. 2191 would reduce total U.S. greenhouse gas emissions by up to 66% from 2005 levels by 2050. S. 2191 would establish an absolute cap on the emissions from covered sectors and would allow trading of emissions permits (" allowances ") among covered and non-covered entities. The bill achieves its broad coverage through an upstream compliance mandate on petroleum, natural gas, and fluorinated gas producers and importers, and a downstream mandate on coal consumers, such as electric generators. Specifically, the bill would limit greenhouse gas emissions from all petroleum producers/importers, all natural gas processors, all facilities that use more than 5,000 tons of coal per year, and entities that produce or import more than 10,000 tons annually (carbon dioxide equivalent) of fluorinated gases and other greenhouse gases. S. 2191 does not have a "safety valve"—an alternative compliance option that permits covered entities to pay an excess emissions fee instead of reducing emissions. Instead, the bill creates a Carbon Market Efficiency Board with authority to temporarily adjust the availability of allowances through borrowing and other techniques; however, it is a zero-sum game. Allowances borrowed must be repaid, so the emissions cap is maintained. The bill limits the availability of domestic offsets to 15% of the allowance requirement, with allowances bought in an eligible international allowance market also limited to 15%. Both percentages may be increased by the Carbon Market Efficiency Board if market conditions suggest such action. The bill would permit banking of allowances. For each year 2012 through 2050, the bill specifies the total number of allowances available, then explicitly states the percentage of those allowances that will go to covered and non-covered sectors, as well as the share that will be auctioned . (See Table 1 .) Over time, an increasing share of the allowances are auctioned, while the allowances to covered sectors decrease to zero. Auction proceeds are allocated for various purposes, including technology development and deployment, transition assistance, adaptation, and program administration. (See Table 2 .) Under a proposed amendment to make the bill revenue neutral, a percentage of allowances (starting at 6.1%, increasing to 15.99%) would be auctioned off-the-top for deficit reduction ("Deficit Reduction Fund"). After the Deficit Reduction allowances are allocated, the rest of the allowances ("remainder allowances") are allocated according to the bill as reported. For example, in 2012, 6.1% of the total number of allowances are auctioned for deficit reduction, and an additional 21.5% of the "remainder allowances" are auctioned for program management, technology deployment, adaptation, and other purposes. In addition to the cap-and-trade program, S. 2191 has other key provisions to reduce greenhouse gas emissions. Title VI imposes an "international reserve allowance" requirement on certain "covered" imported goods as a prerequisite for entry into the country. Unlike importers of covered fuels that create greenhouse gases when used (which are directly controlled as covered facilities under S. 2191 ), Title VI would affect certain bulk goods manufactured in processes that generate greenhouse gases (e.g. iron, paper, etc.) that would not be allowed into the country if the allowance requirement were not met.