Climate change
Информация - Экология
Другие материалы по предмету Экология
n addition, in the last two centuries alone, methane concentrations in the atmosphere have more than doubled. Emissions of methane are largely generated by landfills, agriculture, oil and natural gas systems, and coal mining, with landfills comprising the single largest source of the gas. In 1995, methane emissions from U.S. landfills were 63.5 MMTCE, equaling approximately 36 percent of total U.S. methane emissions. Agriculture supplied about 30 percent of U.S. methane emissions in that same year.
Nitrous oxide is also emitted in much smaller amounts than carbon dioxide in the United States and is responsible for approximately 2.4 percent of the U.S. share of the greenhouse effect. However, like methane, it is a more powerful heat trap--310 times more powerful than carbon dioxide at trapping heat in the atmosphere over a 100-year period. The main anthropogenic activities producing nitrous oxide are agriculture, fossil fuel combustion, and the production of adipic and nitric acids. Figures from 1995 show the agricultural sector emitting 46 percent of the total (18.4 MMTCE), with fossil fuel combustion generating 31 percent.
Hydrofluorocarbons (HFCs) are among the compounds introduced to replace ozone-depleting substances, which are being phased out as a result of the Vienna Convention and its Montreal Protocol on Substances That Deplete the Ozone Layer, and the Clean Air Act Amendments of 1990. Because HFCs have significant potential to alter the Earths radiative balance, they are included in this inventory. Many of the compounds of this nature are extremely stable and remain in the atmosphere for extended periods of time, which results in a significant atmospheric accumulation over time. U.S. emissions of these gases have risen nearly 60 percent as they are phased in as substitutes for gases that are no longer allowed under the Montreal Protocol--a rate of growth that is not anticipated to continue. Currently, HFCs account for less than 2 percent of U.S. radiative forcing.
Mitigating Climate Change
In October 1993, in response to the threat of global climate change, President Clinton and Vice President Gore announced the Climate Change Action Plan (CCAP). The Plan was designed to reduce U.S. emissions of greenhouse gases, while guiding the U.S. economy toward environmentally sound economic growth into the next century. This report updates the programs in the CCAP (including an appendix providing one-page descriptions of each program), describes several additional initiatives developed to further reduce emission growth rates, and estimates future emissions based on the current set of practices and programs.
CCAP programs represent an effort to stimulate actions that are both profitable for individual private-sector participants as well as beneficial to the environment. Currently, more than forty programs are in effect, combining efforts of the government at the federal, state, and local levels with those of the private sector. The CCAP has five goals: preserving the environment, enhancing sustainable growth environmentally and economically, building partnerships, involving the public, and encouraging international emission reductions.
Carbon dioxide emissions constitute the bulk of U.S. greenhouse gas emissions. CCAP recognizes that investing in energy efficiency is the most cost-effective way to reduce these emissions. The largest proportion of CCAP programs contains measures that reduce carbon dioxide emissions while simultaneously enhancing domestic productivity and competitiveness. Other programs seek to reduce carbon dioxide emissions by investing in renewable-energy and other low-carbon, energy-supply technologies, which will also provide longer-term benefits, such as increased efficiency and related cost-savings and pollution prevention. A smaller number of programs are targeted at methane, nitrous oxide, and other greenhouse gases (Table 1-2).
A review and update of the CCAP was initiated in 1995, involving a federal government interagency review process and a public hearing and comment period. Revisions to the CCAP (and to the calculation of the effects of its measures) were initiated in light of comments received during this process and are reflected in this document. In addition, as called for under FCCC reporting guidelines, the projections of the effects of measures taken are extended to the year 2020, with the understanding that uncertainties become greater in more distant years.
One of the principal products of the review was an assessment of the effectiveness of the CCAP programs, which were rated to be successful at reducing emissions. Currently, more than 5,000 organizations are participating in programs around the United States. The pollution-prevention benefits of these innovative programs are beginning to multiply rapidly in response to the groundwork laid and the partnerships made. In all, the programs are expected to achieve a large portion of the reductions projected in the CCAP. In fact, it is estimated that these programs will result in energy cost savings of $10 billion annually in 2000.
However, the review has also made clear the significantly reduced impact to be expected from the programs as a result of the nearly 40 percent reduction of CCAP funding by Congress from the amount requested by the President, higher-than-expected electricity demand, and lower-than-expected energy prices. In addition, before the programs implementation, CCAP program managers could not always anticipate the impacts of projected climate change emission reductions. Information available from the first tranche of activity was considered in developing the current projections.
A second product of the review was the identification of several measures that have since been added to the CCAP portfolio. The most significant of these is the Environmental Stewardship Initiative, which greatly expands activities already included in the CCAP, and focuses on reducing the emissions of extremely potent greenhouse gases from three industrial applications--semiconductor production, electrical transmission and distribution systems, and magnesium casting. The expanded initiative is anticipated to reduce emissions by an additional 6.5 MMTCE by 2000, and 10.0 MMTCE by 2010. Other programs include improving energy efficiency in the construction of and supply of energy to commercial and industrial buildings, expanding residential markets for energy-efficient lighting products, and providing information on renewable energy to reduce barriers to the adoption of clean technologies.
The analysis of individual actions is integrated with revised forecasts of economic growth, energy prices, program funding, and regulatory developments to provide an updated comprehensive perspective on current and projected greenhouse gas emission levels. This analysis involved an updating of the baseline calculation in light of new economic assumptions regarding energy prices, economic growth, and technology improvements, among other factors. In 1993, the first U.S. submission projected year 2000 baseline emissions to be 106 MMTCE above their 1990 levels; with current program funding, emissions are now projected to exceed 1990 levels by 188 MMTCE. Two principal factors are responsible:
- The analysis used to develop CCAP significantly underestimated the reductions that would be needed by programs to return emissions to 1990 levels by the year 2000. This was due to several factors, including lower-than-expected fuel prices, strong economic growth, regulatory limitations within and outside of CCAP, and improved information on emissions of some potent greenhouse gases.
- In addition, diminished levels of funding by Congress have affected both CCAP programs and other federal programs that reduce emissions, limiting their effectiveness.
While neither the measures initiated in 1993 nor the additional actions developed since then and included in this report will be adequate to meet the emissions goal enunciated by the President, they have significantly reduced emissions below growth rates that otherwise would have occurred. Based on current funding levels, the revised action plan is expected to reduce emissions by 76 MMTCE in the year 2000--or 70 percent of the reductions projected in the CCAP. Annual energy cost savings to businesses and consumers from CCAP actions are anticipated to be $10 billion (1995 dollars) by the year 2000. Even greater reductions are estimated from these measures in the post-2000 period: reductions of 169 MMTCE are projected for 2010, and 230 MMTCE for 2020. Annual energy savings are projected to grow to $50 billion (1995 dollars) in the year 2010.
A separate component of this chapter addresses the U.S. Initiative on Joint Implementation. Projects undertaken through this initiative allow private-sector partners to offset emissions from domestic activities through reductions achieved in other countries. The Climate Convention established a pilot program for joint implementation at the first meeting of the Conference of the Parties. Guidelines for reporting under the pilot program were established by the Subsidiary Body for Scientific and Technological Advice at its fifth session in February 1997. This report uses those guidelines to report on project activity.
Table 1-2
Summary of Actions to Reduce Greenhouse Gas Emissions
(Million Metric Tons of Carbon Equivalent)Action
NumberAction Title1993 Action
Plan EstimateRevised Estimate*20002000200520102020 Residential & Commercial Sector Actions26.910.329.453.0 78.41Rebuild America2.01.63.06.3 7.11 & 2Expanded Green Lights and Energy Star Buildings3.63.48.516.3 30.