In 1990, the Congress enacted the Global Change Research Act. This act, among other things, required the administration to (1) prepare and at least every 3 years revise and submit to the Congress a national global change research plan, including an estimate of federal funding for global change research activities to be conducted under the plan; (2) in each annual budget submission to the Congress, identify the items in each agency’s budget that are elements of the United States Global Change Research Program (USGCRP), an interagency long-term climate change science research program; and (3) report annually on climate change “expenditures required” for the USGCRP. In response to the requirements of the 1990 act, the administration reported annually from 1990 through 2004 on funding for climate change science. From 1990 through 2001, the reports presented detailed science funding data for the USGCRP. Federal climate change science programs were reorganized in 2001 and 2002. In 2001, the Climate Change Research Initiative (CCRI) was created to coordinate short-term climate change research focused on reducing scientific uncertainty, and in 2002, CCSP was created to coordinate and integrate USGCRP and CCRI activities. CCSP is a collaborative interagency program designed to improve the government wide management of climate science and research. With respect to federal research, OMB, in annual reports and testimony before the Congress, reported climate change funding for 1993 through 2004 using four categories: Technology, which includes the research, development, and deployment of technologies and processes to reduce greenhouse gas emissions or increase energy efficiency. Funding for this category focuses on programs for energy conservation, renewable energy, and related efforts. Science, which includes research and monitoring to better understand climate change, such as measuring changes in forest cover and land use. International assistance, which helps developing countries address climate change by, for example, providing funds for energy efficiency programs. Tax expenditures related to climate change, which are federal income tax provisions that grant preferential tax treatment to encourage emission reductions by, for example, providing tax incentives to promote the use of renewable energy. Over the same time period, the administration also has reported annually on funding specifically for climate change science. CCSP is currently responsible for preparing these climate change science reports, which duplicate to some extent data provided by OMB in the science category. In 1992, the United States ratified the United Nations Framework Convention on Climate Change, which has as its objective the stabilization of greenhouse gas concentrations in the earth’s atmosphere but does not impose specific goals or timetables for limiting emissions. In response, federal agencies developed a plan for reducing greenhouse gas emissions, primarily through voluntary efforts by companies, state and local governments, and other organizations. Since that time, federal agencies have sponsored voluntary programs that encourage private and public sector entities to curb their greenhouse gas emissions by providing technical assistance, education, research, and information sharing. The administration has promoted such voluntary programs, along with other measures, as an alternative to mandatory emissions reductions. In February 2002, the president announced a Global Climate Change Initiative to reduce the rate of increase in greenhouse gas emissions in the United States. Specifically, he established the goal of reducing the emissions intensity of the United States by 18 percent between 2002 and 2012. Emissions intensity is a ratio calculated by dividing emissions in a given year by economic output for that year. In support of this goal, the president announced two new voluntary programs aimed at securing private sector agreements to voluntarily reduce greenhouse gas emissions or emissions intensity. Climate Leaders, an Environmental Protection Agency (EPA)-sponsored government-industry partnership established in February 2002, works with firms to develop long-term climate change strategies. According to EPA officials, as of November 2005, 74 firms were participating in the program. Climate VISION (Voluntary Innovative Sector Initiatives: Opportunities Now), introduced in February 2003 and coordinated by the Department of Energy (DOE) in cooperation with EPA and other federal agencies, works with trade groups to develop strategies to reduce their members’ greenhouse gas emissions intensity. Most industries participating in the program are represented by a single trade group. As of November 2005, 14 industry sectors and the Business Roundtable—an association of chief executive officers representing diverse sectors of the economy—were participating in the program. According to DOE, the trade groups participating in Climate VISION typically have high energy requirements. OMB reports indicated that federal funding on climate change increased from $2.35 billion in 1993 to $5.09 billion in 2004, or from $3.28 billion to $5.09 billion after adjusting for inflation, and that funding increased in three of the four categories between 1993 and 2004. However, changes in reporting methods limit the comparability of funding data over time, making it unclear whether total funding actually increased as reported. OMB reports also indicated that 12 of the 14 federal agencies receiving funding for climate change programs in 2004 received more funding in that year than they had in 1993, but again, unexplained modifications in the reports’ contents limit the comparability of agencies’ funding data, making it difficult to determine whether funding increased as OMB reported. We found that federal funding for climate change, as reported by OMB, increased from $2.35 billion in 1993 to $5.09 billion in 2004 (117 percent), or from $3.28 billion to $5.09 billion (55 percent) after adjusting for inflation, and reported funding increased for three of the four categories between 1993 and 2004. However, changes in reporting methods limit the comparability of funding data over time, and therefore it was unclear whether total funding actually increased as OMB reported. We were unable to compare changes in the fourth category–climate-related tax expenditures–because OMB reported estimates for proposed but not existing tax expenditures from 1993 to 2004. Specifically, for 1993 through 2004, we found the following: Technology funding, as reported by OMB, increased from $845 million to $2.87 billion (240 percent), or from $1.18 billion to $2.87 billion (143 percent) in inflation-adjusted dollars. The share of total climate change funding devoted to technology increased from 36 percent to 56 percent. However, we identified several ways that technology funding presented in OMB’s more recent reports may not be comparable to previously reported technology funding. For example, OMB added accounts to the technology category that were not reported before or were presented in different categories and did not explain whether these accounts reflected the creation of new programs or a decision to count existing programs for the first time. OMB also expanded the definitions of some accounts to include more activities without clarifying how the definitions were changed. Furthermore, OMB reports include a wide range of federal climate-related programs and activities, some of which–such as scientific research on global environmental change–are explicitly climate change programs, whereas others–such as technology initiatives promoting emissions reduction or encouraging energy conservation–are not solely for climate change purposes. Science funding increased from $1.31 billion to $1.98 billion (51 percent), according to both OMB and CCSP, or from $1.82 billion to $1.98 billion (9 percent) in inflation-adjusted dollars. However, science’s share of total climate change funding decreased from 56 percent to 39 percent. OMB and CCSP generally presented consistent climate change science funding totals from 1993 through 2004. CCSP reports also presented more detailed data, but these data were difficult to compare over the entire period because CCSP periodically introduced new categorization methods without explaining how the new methods related to the ones they replaced. Specifically, over the period CCSP used seven different methods to present detailed science funding data, making it impossible to develop consistent funding trends for the entire timeframe. International assistance funding reported by OMB increased from $201 million to $252 million (25 percent), but decreased from $280 million to $252 million (10 percent) in inflation-adjusted dollars. Moreover, its share of total climate change funding decreased from 9 percent to 5 percent. International assistance funding reported by OMB was generally comparable over time, although several new accounts were added without explanation. Tax expenditures were not fully reported by OMB for any year, even though climate-related tax expenditures amounted to hundreds of millions of dollars in forgone federal revenue in fiscal year 2004. Although not required to do so, OMB reported proposed climate-related tax expenditures. However, OMB did not report revenue loss estimates for existing climate change-related tax expenditures. Whereas OMB reported no funding for existing climate change-related tax expenditures in 2004, the federal budget for that year listed four tax expenditures related to climate change, including estimated revenue losses of $330 million for incentives to develop certain renewable energy sources. Table 1 shows federal climate change funding by category between 1993 and 2004. Table 2 shows funding data for the seven largest technology accounts, which accounted for 92 percent of technology funding in 2004. OMB and CCSP officials told us that time constraints and other factors contributed to changes in report structure and content over time. For example, OMB officials said that the short timeline for completing the report required by the Congress (within 45 days of submitting the upcoming fiscal year’s budget for the three most recent reports) limited OMB’s ability to analyze data submitted by agencies. OMB and CCSP officials also noted that each report was prepared in response to a one- time requirement and that they were not directed to use the same report format over time or to explain differences in methodology from one report to another. The director of CCSP told us that changes to climate change science reports, such as the creation and deletion of different categorization methods, were made because CCSP was changing towards a goals-oriented budget, and categorization methods changed as the program evolved. The director also said that future reports will explicitly present budget data as it was reported in prior reports to retain continuity, even if new methods are introduced.