Climate change

|temperatures would continue to increase for several decades, and sea |

|level would continue to rise for centuries. |

|Vulnerability, Likely Impacts, and Possible Responses |

|Climate change is likely to have wide-ranging and mostly adverse |

|effects on human health. Direct and indirect effects can be expected |

|to lead to increased mortality. |

|Coastal infrastructure is likely to be extremely vulnerable. A |

|50-centimeter (20-inch) rise in sea level would place approximately |

|120 million people at risk. |

|Natural and managed ecosystems are also at risk: forests, |

|agricultural areas, and aquatic and marine life are all susceptible. |

| |

|However, adaptation and mitigation options are numerous. Significant |

|reductions in net greenhouse gas emissions are technically possible |

|and can be economically feasible, using an extensive array of |

|technologies and policy measures that accelerate technology |

|development, diffusion, and transfer. |

|Socioeconomic Issues |

|Early mitigation may increase flexibility in moving toward a |

|stabilization of atmospheric concentrations of greenhouse gases. |

|Economic risks of rapid abatement must be balanced against risks of |

|delay. |

|Significant "no regrets" opportunities are available in most |

|countries. Next steps must recognize equity considerations. |

|Costs of stabilization of emissions at 1990 levels in OECD countries |

|could range considerably (from a gain of $60 billion to a loss of |

|about $240 billion) over the next several decades. |

National Circumstances

In responding to the threat of global climate change, U.S. policymakers

must consider the special circumstances created by a unique blend of

challenges and opportunities. The National Circumstances chapter of this

report attempts to explain the particular situation in the United States--

including its climate, natural resources, population trends, economy,

energy mix, and political system--as a backdrop for understanding the U.S.

perspective on global climate change.

The United States is unusual in that it encompasses a wide variety of

climate conditions within its borders, from subtropical to tundra. This

diversity complicates the discussion of impacts of global climate change

within the United States because those impacts would vary widely. This

diversity also adds to U.S. emission levels, as heating and cooling demands

drive up emissions. Recent record levels of precipitation--both in snowfall

and rain--consistent with what could be expected under a changed climate,

have raised the awareness of climate impacts at the local and regional

levels, and may make it somewhat easier to predict the effects of increased

precipitation.

The United States also is uncommonly rich in land resources, both in

extent and diversity. U.S. land area totals about 931 million hectares (2.3

billion acres), including grassland pasture and range, forest, and

cropland. Forested land has been increasing, while grasslands and croplands

are slowly declining and being converted to other uses. The decline in

wetlands has slowed significantly as a result of the "no net loss" policy

being implemented.

With just over 265 million people, the United States is the third most

populous country in the world, although population density varies widely

throughout the country, and is generally very low. Although population

increase is moderate from a global perspective, it is high relative to the

average for all industrialized countries. Moreover, the number of

households is growing rapidly. These and other factors drive U.S. emissions

to higher per capita rates than those in most other countries with higher

population densities, smaller land areas, or more concentrated distribution

of resources to population centers.

The U.S. market economy is based on property rights and a reliance on

the efficiency of the market as a means of allocating resources. The

government plays a key role in addressing market failures and promoting

social welfare, including through the imposition of regulations on

pollutants and the protection of property rights, but is cautious in its

interventions. Thus, the infrastructure exists to limit emissions of

greenhouse gases--although the strong political and economic preference is

to undertake such controls through flexible and cost-effective programs,

including voluntary programs and market instruments, where appropriate.

U.S. economic growth averaged 3 percent annually from 1960 to 1993, and

employment nearly tripled as the overall labor force participation rate

rose to 66 percent. The service sector--which includes communications,

utilities, finance, insurance, and real estate--has grown rapidly, and now

accounts for more than 36 percent of the economy. The increasing role of

trade in the U.S. economy heightens concerns about the competitiveness

effects of climate policies.

During the 1980s, the U.S. budget deficit grew rapidly, as did the

ratio of debt to gross domestic product, and a political consensus emerged

on the goal of a balanced budget. The result is a tighter federal budget

with many competing priorities.

The United States is the world's largest energy producer and consumer.

Abundant resources of all fossil fuels have contributed to low prices and

specialization in relatively energy-intensive activities. Energy

consumption has nearly doubled since 1960, and would have grown far more,

because of growth in the economy, population, and transportation needs, had

it not been for impressive reductions in U.S. energy intensity. Industrial

energy intensity has declined most markedly, due to structural shifts and

efficiency improvements. In the residential and commercial sectors,

efficiency improvements largely offset the growth in the number and size of

both residential and commercial buildings. Likewise, in the transportation

sector, efficiency moderated the rise in total fuel consumption from 1973

to 1995 to only 26 percent, despite dramatic increases in both the number

of vehicles and the distances they are driven. Fossil fuel prices below

levels assumed in the 1993 Climate Change Action Plan, however, have

contributed to the unexpectedly large growth in U.S. emissions.

While unique national circumstances point to the reasons for the

current levels (and increases) in U.S. emissions, they also suggest the

potential for emission reductions. Successful government and private-sector

programs are beginning to exploit some of the inefficiencies in the

manufacturing sector. The development of new, climate-friendly technologies

is a rapidly growing industry, with significant long-term potential for

domestic and international emission reductions.

Greenhouse Gas Inventory

Inventorying the national emissions of greenhouse gases is a task

shared by several departments within the executive branch of the federal

government, including the Environmental Protection Agency, the Department

of Energy and the Department of Agriculture. The Greenhouse Gas Inventory

chapter summarizes the most current information on U.S. greenhouse gas

emission trends--and represents the 1997 submission from the United States

in fulfillment of its annual inventory reporting obligation. The estimates

presented in this chapter were compiled using methods consistent with those

recommended by the IPCC Guidelines for National Greenhouse Gas Inventories;

therefore, the U.S. emissions inventory should be comparable to those

submitted by others under the FCCC.

Table 1-1 summarizes the recent trends in U.S. greenhouse gas emissions

from 1990 to 1995. The three most important anthropogenic greenhouse gases

are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

Hydrofluorocarbons (HFCs) are also inventoried. Consistent with the

requirements in the Climate Convention only to address emissions of gases

not controlled by the Montreal Protocol on Substances That Deplete the

Ozone Layer, chlorofluorocarbon (CFC) emissions are not inventoried, nor

are mitigation measures for these compounds described.

| |ct | | | | | | |

| |and | | | | | | |

| |ect | | | | | | |

| |ts | | | | | | |

| |1990 |1991 |1992 |1993 |1994 |1995 | |

|Carbon Dioxide (CO2) |1,228|1,213|1,235|1,268|1,291|1,305 | |

|Fossil Fuel |1,336|1,320|1,340|1,370|1,391|1,403 | |

|Industrial Processes |17 |16 |17 |18 |19 |19 | |

|Total |1,353|1,336|1,357|1,388|1,410|1,422 | |

|Forests (sink)* |(125)|(123)|(122)|(120)|(119)|(117) | |

|Methane (CH4) |170 |172 |173 |171 |176 |177 | |

|Landfills |56 |58 |58 |60 |62 |64 | |

|Agriculture |50 |51 |52 |52 |54 |55 | |

|Coal Mining |24 |23 |22 |20 |21 |20 | |

|Oil and Natural Gas |33 |33 |34 |33 |33 |33 | |

|Other |6 |7 |7 |6 |6 |6 | |

|Nitrous Oxide (N2O) |36 |37 |37 |38 |39 |40 | |

|Agriculture |17 |17 |17 |18 |18 |18 | |

|Fossil Fuel |11 |11 |12 |12 |12 |12 | |

|Industrial Processes |8 |8 |8 |8 |9 |9 | |

|HFCs |12 |12 |13 |14 |17 |21 | |

|PFCs |5 |5 |5 |5 |7 |8 | |

|SF6 |7 |7 |8 |8 |8 |8 | |

|U.S. Emissions |1,583|1,570|1,592|1,624|1,657|1,676 | |

|Net U.S. Emissions |1,458|1,447|1,470|1,504|1,538|1,559 | |

|1990-91 and 1993-95 | | | | | | | |

Overall, U.S. greenhouse gas emissions have increased annually by just

over one percent. The trend of U.S. emissions--which decreased from 1990 to

1991, and then increased again in 1992--is a consequence of changes in

total energy consumption resulting from the U.S. economic slowdown in the

beginning of this decade and its subsequent recovery.

Carbon dioxide accounts for the largest share of U.S. greenhouse gases--

approximately 85 percent--although the carbon sinks in forested lands

offset CO2 emissions by about 8 percent. During 1990-95, greenhouse gas

emissions continued to rise in the United States, with CO2 increasing

approximately 6 percent, methane approximately 4 percent, N2O nearly 10

percent, and HFCs approximately 7 percent. Fossil fuel combustion accounts

for 99 percent of total U.S. CO2 emissions. (Chapter 3 of this report

explains the use of MMTCE in converting emissions of greenhouse gases to

carbon equivalents.)

Although methane emissions are lower than CO2 emissions, methane's

footprint is large: in a 100-year time span it is considered to be twenty-

one times more effective than CO2 at trapping heat in the atmosphere and is

responsible for about 10 percent of the warming caused by U.S. emissions.

In 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 Earth's 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

Страницы: 1, 2, 3, 4

МЕНЮ

Climate change

ИНТЕРЕСНОЕ