Global Climate Change: U.S. Greenhouse Gas Emissions - Status, Trends, and Projections

CRS Report for Congress
Global Climate Change:
U.S. Greenhouse Gas Emissions
St atus, T rends, and Projections
Updated August 15, 2003
John Blodgett and Larry Pa rker
Specialists in Energy and En vironmental Po licy
Resources, Sc ience, and Industry Division

Congressional Research Service ˜ The Library of Congress

Global Climate Change:
U.S. Greenhouse Gas Emissions —
Status, Trends, and Projections
This report reviews U.S. emissions of greenhouse gases in the contex ts both o f
domestic policy and of international obligations and p roposals. On October 15,
1992, the United S tates ra tified t he United Nations Framework C onvention o n
Climate Change (UNFCCC), which entered i nto force on March 21, 199 4 . T h is
committed t he United S tates t o “national policies” t o limit “its anthropogenic
emissions of greenh ouse gases,” with a voluntary goal o f returning “emissions of
carbon diox ide [ CO2] and other greenhouse gases [ m ethane (CH4), nitrous ox ide
(N 2O ) , h yd r o f l uorocarbons (HFC s), p erfluorocarbons (PFC s), and sulfu r h e x a f l u o r i d e
(S F6)] ” at t he “end o f t he decade” to “their 1990 levels.”
Subsequent l y, i n t he 1997 Kyoto P rotocol t o t he UNFCCC, the United S tates
participat ed i n n e gotiations that ended with agreem ent on further reductions that
could become legally binding. The United States s igned t he Kyoto P rotocol i n 1998,
but Pres ident C linton did not send it to the S enat e for advice and consent. Pres ident
Bu sh has s aid t hat h e rejects t he Protocol, and former U.S. Environmental P rotection
Agency Administrat or Christine T o d d Whitman t old reporters that the
Administration would n ot be pursuing t he UNFCCC commitment either. Instead,
President Bush h as proposed to shift t he na tion’s climate change program from a go al
of reducing emissions per s e t o a go al of re ducing energy i ntensity — t he amount of
greenhouse gases emitted p er unit o f econo mic productivity. Under t he proposal, t he
intensity, whic h h as b een declining for a number o f years, would d ecline 18%
between 2002 and 2012, as opposed to a 14% projected “business as u sual” d ecline.
Meanwhi l e, t he UNFC C C “end o f t he decade” deadl i n e h as passed an d U.S .
greenhouse gas emissions continue on an upward t rend, though with dips in 1991 and
in 2001, attributed mostly to economic slowdowns. Based on historical data, 2001
emissions were about 13% in ex cess of t he UNFCCC goal . Overall, from 1990 to
2001, U.S. greenhouse gas emissions (weighted b y global warming potential) have
increased an average o f about 1.1% per year. P rojections suggest that U.S. emissions
wi l l cont i nue t o ri se for at l e a s t t he nex t decade. R eversi n g t he upward t rend i n
greenhouse gas emissions would represent an ex traordinary t echnical and political
challenge t o U.S. energy a nd environmental policy.
This report will be updated as n ecessary.

U.S. Greenhouse Gas Emissions and Baselines ...........................2
Emissions Projections ..............................................5
The Climate Action Report Projection .............................6
Effect onProjections ofVaryingAssumptions .......................9
Status ofEmissions RelativetoGoals .................................12
AdditionalConsiderations in AssessingPossibleReductions ..............14
CarbonSequestration ......................................14
Emissions Trading ........................................15
Fi gure 1. U.S. Emissions of CO2: Historical and P rojected (2005, 2010) .......7
Fi gure 2. U.S. Emissions of CH4,N20,andHFCs,PFCs,andSF6:
Historical and P rojected (2005, 2010) ..............................8
Fi gu re 3. U.S. Aggregate Gross Emissions of Six Greenhouse Gases:
Historical and P rojected (2005, 2010) (MMTCE) ....................10
Fi gu re 4. Greenhouse Gas In tensity: P resident’s In itiative .................14
Table 1 . U.S. Greenhouse Gas Emissions (MMTCE), 1990-2001 ............3
Table 2 . U.S. Baseline Year Greenhouse Gas Emissions ...................4
Table 3 . U.S. Greenhouse Gas In tensity (1990-2001) .....................6
Table 4. Impact of Economic Assumptions on Projections of CO2 Emissions . 11
Table 5 . Impact of Technology/ Effici ency Assumptions on Projections of
CO2 Emissions ...............................................12

Global Climate C hange:
U.S. Greenhouse Gas Emissions
Status, Trends, and Projections
This report reviews U.S. emissions of greenhouse gases in the contex ts both o f
domestic policy and of international obligations and p roposals. On October 15,
1992, the United S tates ra tified t he United Natio n s Framework C onvention o n
Climate Change (UNFCCC), which entered i nto force on March 21, 1994. By this
action, the n ation m ade a l egally non-bindi ng commitment to “national policies” to
limit “its anthropogenic emissions of greenhouse gases,” which are believed t o pose1
a r i s k of global climate change. The goal was to return “these anthropogen i c
emissions of carbon diox ide and other greenhouse gases” at t he “end o f t he decade”
to “their 1990 levels.” This go al was voluntary, to “demon s t r a t e that developed
countries are t aking t h e lead in modifying l onger-term t rends in anthropogenic2
e m i s s i ons consistent with the objective of t he Convention.” The C onvention
established s tandards for inventoryi ng and reporting greenhouse gas emissions.
Subsequently, t he United S tates participat ed in negotiating t he Kyoto P rotocol3
to the UNFCCC. Under t he Kyoto P rotocol, the United S tates would have m ade a
legally binding agreement t hat for the 5 -year period 2008-2012, it would reduce its
average annual aggregate carbon-equivalent emissions of six gas es by 7% below
speci fi ed basel i n e years. 4 However, while Pres ident C linton s igned t he Protocol in
1998, he did not send it to the S enate for its advice and consen t; and P resident
George W . Bu sh has s aid t hat h e h as no intention o f pursuing t he Kyoto P rotocol —5
t h at i t i s “fat al l y fl awed.”
Nonetheless, other n ations continue efforts t o implement t h e K yo to Protocol,
and t h e United S tates remains obligated under t he UNFCCC to inventory its
emissions of greenhouse gases and t o pursu e voluntary reductions. However, as

1 T his report does not address t he underlyi ng debate over gl ob a l c l i mate c hange a nd the
potential r ole of humans i n contributing t o it. On the s cience and policy of global climate
change , s ee CRS Issue Brief IB89005, Global Climate Change .
2 UNFCCC, Ar t i c l e 4, Commi t me n t s , s e c t i ons 2( a ) a n d ( b) .
3 On the a gr eement, see CRS Report RS30692, Global Climate Change Treaty: The Kyoto
4 T echnically, t he net carbon-equiva lent emissions of the s ix gr eenhouse gases for t he 5-year
period 2008-2012 are not to exceed 5 times 93% of the baseline emi ssions. K yoto Protocol,
A r t i c l e 3 ( 1). T his i s equivalent to the average annual emission load during t he 5-ye a r
period being 7% below the baseline.
5 White House, Office of the Press Secretary, “President Bush Di scusses G l o b a l Climate
Change ,” J une 11, 2001.

described b elow, P resident Bu sh has announced a voluntary p rogram to reduce t he
intensity of U.S. greenhouse gas emissi ons per unit of economic productivity.6 Bas e d
on this initiative, according t o f o r m e r Environmental P rotection Agency
Administrat or Christine Todd Whitman, “t he Bush Administration does not intend
to pursue emissions cuts it committed t o” in the UNFCCC.7
It is in this contex t, then, t hat t his report s et s out the bas eline emissions that the
Uni t ed S t at es h as est abl i s hed and port rays t rends i n em i ssi ons over t he past decade; 8
notes the current status of U.S. emissions a s c o mpared to the UNFCCC go als; and
reviews p rojections and, as a point of reference, com p ares t h em t o t h e K yo t o P rot ocol
emissions commitment s . (Assessing that prospective commitment does not imply
t h at the United S tates s hould reduce emissions, only what would be required if it
were t o j o i n t h at agreem ent t o reduce em i ssi ons.)
In what follows, figures for emissions are point estim a t e s 9 and rounded t o
millions of metric tons of carbon equivalents (MMTCE10). As will be discussed, the
data are o f v aryi ng robustness and may b e s ubject to adjustments. The d ata for CO2,
w h ich accounts for over 80% of domestic greenhouse gas emissions, are t h e m o s t
robust, being l argely based o n comprehensive fuel use d ata. Subsumed estimates and
uncert ai n t i es i n p roj ect ed em i ssi ons have great er effect t h e furt h er i n t o t h e fut ure one
looks. But even allowing for t hese i m p r e c i s i ons, t he trendline of aggregat e U .S .
emis s i o n s o f greenhouse gases is clear: over t he decade o f t he 1990s emissions
trended upward, and t hey are project ed to continue to rise in the future.
U.S. Greenhouse Gas Emissions and B aselines
Pursuant to the United Nations Fram ework C onvention o n C limate Change, t he
United S tates h as published “ national i nv e n t o r i es of anthropogenic emissions by
sources and removals by sinks of all greenhouse gases not controlled b y t he Montreal
Protocol, using comparable methodologies ... agreed upon by the C onference of the11
Parties.” (S ee Table 1.)

6 F o r d o c u me n t s o n t h e A d mi n i s t r a t i o n p l a n, s e e [ ht t p : / / www.whi t e ho u s e . go v/ n e w s / r e l e a s e s /

2002/02/climatechange.html ].

7 “Bush Emi ssions Plan Seen Replacing Regs ,” Platts Inside Energy (Feb. 25, 2002), p. 9.
8 Envi ronmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks:

1990-2001 (April 2003), EPA 430R03004.

9 Although emi ssions data are t ypic a l l y p r esented as i ndivi dual f igures for each year, t his
single number ( point estimate) actually re p r e s e n ts a r ange bounded by potential errors
arising from assumptions underlyi ng the data.
10MMT CE figur e s c o mb i ne the variable greenhouse effects of t he different gases by
calculating and summi ng their equivalent ef f e c t s , with carbon dioxide serving as t he
reference gas. Global warmi ng potential f igures have an uncertainty of + or - 35%; a recent
recalculation i s not included i n t he current figures ( see discussion in EPA, Inventory of U.S.
Greenhouse Gas Emissi ons and Sinks: 1990-2001 (April 2003), EPA 430R03004. pp. 6-9).
11 UNFCCC, Ar t i c l e 4, s e c t i o n 1 ( a ) a nd Ar t i c l e 12, s e c t i o n 1 ( a ) .

Table 1. U .S. Greenhouse Gas Emissions (M M T CE), 1990-2001
Gas 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
CO2 1,365 1,354 1,381 1,412 1,438 1,455 1,504 1,526 1,531 1,549 1,604 1,580
CO2 (sinks) a (293) (289) (291) (291) (292) (290) (289) (229) (226) (229) (228) (229)
CH4 176 176 176 174 176 177 174 172 170 168 167 165
N2 O 108 110 113 113 120 118 120 120 119 117 117 116
235HFCs, PFCs, SF6 26 24 25 26 26 27 31 32 35 33 33 30
Total emissions 1,675 1,664 1,694 1,726 1,760 1,777 1,829 1,850 1,855 1,867 1,921 1,892
iki/CRS-98-Net emissions 1,382 1,375 1,403 1,435 1,468 1,487 1,540 1,621 1,629 1,638 1,693 1,663
leakEnvi ronmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2001 (April 2003), EPA 430R03004. (Data f or 1991-
provided by EPA.) Following international c onvention, EPA presents t he data in teragr ams of CO2 equivalent; CRS has converted t he figures t o million metric
://wikiof carbon equivalent (MMTCE ), a metric t hat i s more f amiliar t o most U.S. policymakers.
use c hanges and f orestry s inks that seque ster carbon; included i n net emissions total only.

The Environmental P rotection Agency (EPA) publishes t he official emissions
data annually.12 The United S tates also from time to time reports on emissions and
ex plai ns its climate ch an ge p r ograms in the Climate Action Report (CAR) to the
United Nations; t he third CAR was published i n 2002.13
The U.S. b aselines for t he UNFCCC and t he Kyoto P rotocol are shown i n Table
2. For the UNFCCC commitment, t he baseline i s 1990 emissions, or 1,675
MMTC E ; i f t he Uni t ed S t at es h ad acceded t o t h e Kyo t o t arget s, t h e b asel i n e woul d
have been 1,676 MMTCE, a negl i g i b l e d i f f erence. By definition, sinks are not
incl uded i n cal culating t he baselines .
Table 2. U .S. B aseline Year Greenhouse Gas Emissions
Green h o u s e Gas B a sel i n e Year E mi ssi on s (MMT CE )
Carbon diox ide (CO2 ) 1990 1,365
Methane (CH4) 1990 176
Nitrous ox ide (N2O) 1990 108
Hydrofluorocarbons (HFC s)
UNFCC Kyoto UNFCC KyotoPerfluorocarbons (PFC s)
Sulfur hex afluoride (SF6)
Source: EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 - 2001) Apr i l

2003, EPA 430R03004.

T h e emissions baselines shown i n Table 2 are not immutable. Each annual
report i ncludes updated es timates b ased on methodological and d ata revisions,
although s uch changes are u sually small. Revisions are d iscussed at s ome l engt h i n
each report. The criteria for calculating emissions agreed upon by the C onference of
Parties h inge on both current techni cal knowledge and policy j udgments. New
t echni cal i n form at i o n can change fact ors, for ex am p l e concerni ng cal cul a t i o n o f
greenhouse gas equivalents; and policy j udgments can be adjusted, for ex ample
concerning the time frame for cal culating effect s. In addition, a few technical issues
remain unres o l v ed, for ex ample in assigning emissions from fuels burned i n
international t ravel. However, an y changes tend to be modest, s eldom affecting t otals

12EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 - 2001 , April 2003,
EPA 430R03004, available at [ ng.nsf/content/
Resour ceCent e r Publ i cat i onsGHGEmi ssi onsUSEmi ssi onsInve nt or ml ] .
13The Climate Action Reports, submitted by t he United States of America under t he United
Nations Framework Convention on Climate Change, appeared in October 1994, J uly 1997,
and M ay 2002; for t he third r eport, see U.S. Departmen t o f S t a t e, U.S. Climate Action
Report (May 2002), available at [ ng.nsf/cont e n t/
ResourceCenterPublicationsUS ClimateActionReport.html ].

much more than plus or minus 1%, ex cept for sequestration figures, which have been
subj ect t o l arger changes. 14
Besides act ual quantities o f emissions, an alternative m eas ure of a nation’s
contribution t o global warming i s “greenhouse gas intensity of the economy” — t hat
is, emissions per unit of gross domestic product (GDP). In effect, t his m e a s ure
focuses o n t he efficiency of the econom y i n t erms of greenhouse gas emissions: t he
more efficient, the fewer emissions per dollar o f economic output and t hus the l ower
the “greenhouse gas intensity.” Fo r t he Un ited S tates, greenhouse gas intensity has
been d e c l i n i n g s i n ce at least t he 1980s; for the 1990s, t he decline i n i ntensity was
about 10%, b ased on net emissions 15 (see Table 3).
Emissions Projections
Projecting greenhouse gas emissions i nvolves m odeling t he nation’s economic
gro wth and activity, with speci al attention t o variables affecting fossil fuel
combustion. The m odeling also d epe n d s o n assumptions about energy policy
directions. If reducing emissions becomes a go al , t hen p roj ect i ons becom e subj ect
to the outcome of unresolved i ssues in how the emissions reductions goals might be
For ex ample, t he major s ource of C O 2 e missions, fossil fuel combustion, is
influen ced by overall economic activity and growth as wel l as by energy policy
decisions such as development o f non-car bon based s ubstitutes, the rate of adoption
of energy efficient t echnologies, and t he retirement rate o f nuclear facilities, among
o t h e r s . These policy factors are difficult to predict i n t he absence o f a concr e t e
climate change policy.16 The climate change plan proposed by President Bush i n
February 2002 provides s ome n ew policy d irections, but many elements depend on
congressional action (e.g. , for funding) o r voluntary p rivate sector initiatives, m aking
projections of their impact problematic.

14 See “ Change s i n T his Year’s Inve ntory Report,” EPA, Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2001, pp. Change s-1 - Change s-13.
15 Followi n g t he Administration’s practice, discussions in this report of greenhouse gas
intensity are based on net emissions per unit of economic activity.
16 On current federal policies, see CRS Report RL31921, Climate Chan g e : F e deral Laws
and Policies Related to Greenhouse Gas Reductions.

Table 3. U .S. Greenhouse Gas Intensity ( 1990-2001)
GDP (billions of ch ai ned Greenhouse Gas In tensity (metric
(1996) dollars) tons carbon equivalent per million
Total Emissions Net Emissions
Source: T able 1; Economic Report of t h e P r esident , February 2003, T a ble B-2; CRS
The Climate Action Repor t Projection
The t hird U.S. Climate Action Report (CAR 2002) p rojects greenhouse gas
emissions at 5-year intervals t hrough 2020. For t his report, the p rojections are
followed only t o 2010 (see Fi gu res 1 a n d 2 ), because of the d ifficulties i n p rojecting
into the m ore d istant future. Also, 2010 provi des a basis for evaluating a relationship
to the Kyoto Protocol target s.

Figure 1 . U.S. E missions of CO 2: Historical and Projected (2005, 2010)
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
CO2 CO2 (sink s) Net C O2
: Historical data (through 2001): EPA, Invento ry of U.S. Greenhouse Gas Emissions and Sinks: 1990 - 2001, April 2003, EPA 430R03004, pp. ES-2 - ES-4. Proj ectio ns (to
U.S. Department o f State, Climate Actio n Report 2002, May 2002. [Data converted to MMT CE by CRS.]

Figure 2 . U.S. E missions of CH 4,N20, and HFCs, PFCs , a nd SF6: Historical and Projected (2005, 2010)
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
CH4 N20 HFCs, PFCs, SF6
: Historical data (thr ough 2001): EPA, Invento ry of U.S. Greenhouse Gas Emissions and Sinks: 1990 - 2001, April 2003, EPA 430R03004, pp. ES-2 - ES-4. Proj ections (to
U.S. Department o f State, Climate Actio n Report 2002, May 2002. [Data converted to MMT CE b y CRS.]

The CAR 2002 estimate for aggregate gross greenhouse emissions 17 in 2010 is
2,213 MMTCE (see Fi gure 3 ). The P resident’s 2002 initiative t o reduce greenhouse
gas i ntensity proposes a s eries o f policy i nitiatives that it estimates “will achieve 100
million t ons of reduced emissions in 2012.”18 Ex t rapol at i n g b et ween t h e CAR 2002
projections from 2010 to 2015 (a 1.9% annual growth rate), t he 2012 project ed
emission level would be 2,298 MMTCE. The President’s i nitiative s uggesting a
decline i n emis s i o n s o f 100 million t ons in 2012 would reduce t his t o 2,198
MMTCE, representing a r e d u ction o f about 4.4% from “business as u sual” gross
greenhouse emissions in that year. In add ition, largely s eparate from federal
activities, a number of state and l ocal governmental initiatives, as wel l as a variet y
of private s ector activities, are underway to address greenhouse gas emissions.
Effect on Pr oj ecti ons of Var yi ng Assumpti ons
CA R 2 002 only m akes point es timates, but some sense of t he implications of
varying assumptions that affect the estimates can be gl eaned from ex amining an
alternative s ource of CO2 emissions data, t he Energy Information Agency’s (EIA’s)19
Annual Energy Outlook series. (Because of m i nor di fferences i n dat a cal cul at i o n
and p resentation, EIA’s annual emissions figu res d iffer s lightly from EPA’s.)
The EIA repo r t ’ s projections of CO2 emissions incl ude sensitivity anal yses to
various changes i n assumpt i o ns, and since C O2 from fuel combustion accounts for
about 80% of U.S. greenhouse gas emissions, t he analys is is a reasonable t est o f t he
projections. Th e a s s u m p t i o n s E IA e x a m i n e s i n c l u d e e c o n o m i c gr o w t h , t e c hnological
innovation, oil prices, electricity demand, and others. The first two, economic
growth and t echnol ogical i nnovation, have the great es t effect on vari ance in
projections of CO2 emissions (see Table 4). Fo r 2010, compared to EIA’s “reference
case” (whi ch i s equi val ent t o a “busi n ess as u sual ” case), l ow econom i c growt h
would reduce p rojected emissions by about 2%, 20 while high economic growth would
increase p rojected emissions by about 3%. C o m pared t o t he reference case t hat
assumes anticipated technological devel opments, s tat i c technology would result i n
emissions rising about 2%, while a “high-technology” case i s p ro jected to reduce
emissions about 2%. The point reference case — CAR’s point estimate —
effect i v el y assum es t he several v ari ances affect i n g em i ssi ons cancel out . But i f al l t he
vari ances i n creasi n g em i ssi ons prove t rue and cum ul at i v e, t h en proj ect ed em i ssi ons
f o r 2010 could b e 5 % o r m ore h igher t han the point estimate; conversely, if all t h e
variances decreasing emissions prove true and cumulative, e m i ssions could b e 5 %
or more lower.

17 CAR 2002 , T able 5-2, p. 74; this exc l u d e s “ Sequestration Removals” and i ncludes
“Adj ustments.”
18 White House, Gl obal Climate Change Policy Book, “Executive Summary,” at
[ ht t p: / / www.whi t e news/ r el eases/ 2002/ 02/ cl i mat echange .ht ml ] .
19 EIA, Annual Energy Outlook 2003 (J an. 2003), DOE/EIA-0383(2003).
20 T he i mpact o f e c o n omi c activity can be seen ( Tabl e 1 ) i n t he fact that gr oss e mi ssions
declined in both 1991 and 2001, in tandem with economic downturns.

Figure 3 . U.S. Aggregate G ross Emissions of Six G reenhouse G ases:
Historical and P rojected (2005, 2010) (MMTCE)
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
Gross Emissions Upper Bound Lower B ound P r es ident's I nitiative
: Historical data (thr ough 2001): EPA, Invento ry of U.S. Greenhouse Gas Emissions and Sinks: 1990 - 2001, April 2003, EPA 430R03004, pp. ES-2 - ES-4. Proj ections (to
U.S. Department o f State, Climate Actio n Report 2002, May 2002. [Data converted to MMT CE by CRS.] Upper and lower bound equal + 5% and - 5%, as d iscussed in text.
t’s initiative is from documents on the Administration p lan at [ http://www. wh i t e h o u s e . g o v / n e ws / r e l e a s e s / 2002/02/climatechange.html].

Table 4. Impact of Economic Assumptions on Projections of
CO2 Emissions
Change in CO2 Emissions from Fuel Use,
Case Comparisons 2010
Lo w R eference High
economic case economic
Economic Growth 1,759 (-2%) 1,800 1,852 (+3%)
2003 R eference High
Technology Case Technology
In tegrated Technology 1,831 (+2%) 1,800 1,759 (-2%)
Source: EIA, Annual Energy Ou tlook 2003 (January 2003) DOE/EIA-0383(2003), pp. 174, 218.
S o m e st udi es suggest t h at even great er vari ance i n proj ect i ons i s possi bl e — for
ex ample, that new energy-efficient t echnol ogies could b e d eployed m ore quickly than
generally assumed i f appropriate policies were i nstituted. A November 2000 DOE
study, commonly called t he “New 5-Lab S t udy,” shows t hat energy efficiency gains
in the t ransportation, industr y, c o m m ercial, and residential s ectors could reduce21
em i ssi ons from t he “busi n ess as u sual ” s cenari o . The “busi n ess as u sual ” s cenari o
in this study is very similar t o EIA’s r e f e r e n c e case, though i t p rojects s omewhat
smaller emissions in 2010 (1,769 MMTCE from fossil fuel combustion, compared
to EIA’s m ost recent p rojection o f 1,800). The study compares “mode r a te” and
“advanced” s cenari o s “t h at are d efi n ed by pol i ci es t hat are consi s t ent wi t h i n creasi n g
levels of public commitment and political resolve t o s olving the nation’s energy-
related challenges .” P o l i cies ex amined incl ude “fiscal incentives , voluntary
program s , regul at i ons, and research and d evel opm ent . ”22
Under t he “moderate scenario,” energy efficiency is improved t hrough s uch
pol i ci es as ex p anded l abel i n g, new effi ci ency standards, tax credits, and cost-shared
R &D; renewable energy grows more rapidly t han i n t he “busi n ess as u sual ” s cenari o ,
and a high er proportion o f nuclear power is re tained. Under t he “advanced scenario,”
which h as more aggressive demand- an d s upply-side policies and a doubling of
R&D, a fe d e r ally sponsored carbon trading s ys tem i s announced in 2002 and

21 DOE, Interlaborat ory W orki ng Group, Scen a r i o s f o r a Clean Energy Future ,
ORNL/CON-476, LBNL-44029, and NREL-T P -620-29379 (Oak Ridge, T N: Oak Ridge
National Laboratory; Berkeley, CA: Lawr ence Berkeley National Laboratory; Golden, CO:
National Renewable Energy Laboratory, Nove mber 2000), a t [
Energy_Eff/CEF.htm] .
22 Ibid., p. 1.4.

implemented in 2005 with a clearing equilibrium price o f $50 per t on of carbon.23
The res ults of this anal ys is are s hown i n Table 5.
Table 5. Impact of Technology/Efficiency Assumptions on
Projections of CO2 Emissions
Total C O2 Emissions from Fuel Use, 2010
Case Comparisons (MMTCE)
“Business as Usual” (BAU) 1,769
Moderate Scenario 1,684 (-5% from BAU)
Advanced Scenario 1,467 (-17% from BAU)
Source: DOE, I nterlaboratory Working Gr oup, Scenario s for a Clean En ergy Futu re,
ORNL/CON-476 and LBNL-44029 (Oak Ridge, T N: Oak Ridge National Laboratory; Berkeley, CA:
Lawr ence Berkeley National Laboratory, 2000), T able 1.8, p. 1.18.
This “New 5-Lab S tudy” t hus suggests t hat i f s pecified policies were adopted,
emissions could b e considerably lower t h a n e v e n EIA’s high -technology s cenario
indicates, b y as m uch as 17% compared to EIA’s h igh-technology reduction i n
emissions of about 2%. EPA and t he Department of Energy (DOE) h ave underway
a number o f p rograms t o foster t he developm ent and deployment of energy-efficient24
The P resident’s greenhouse gas intensity reduction i nitiative i s a new v ariable
affecting p rojections. It would h ave t he effect of reducing antic i p a t e d emissions
bel o w “busi n ess as u sual ” l evel s i n t he fut u re (see Fi gure 3 ); however, t he initiative
does not reflect the l evel of aggressiveness assumed b y t he “New 5-Lab S tudy” for
policy i nterventions to achieve i t s “ advanced scenari o ” for rapi d p enet rat i o n o f
energy-efficient t echnologies.
Status of Emissions Relative to Goals
Under t he UNFCCC, the United S tates committed t o t he voluntary goal of
holding greenhouse gas emissions at the end of the 1990s to their 1990 levels. If t he
United S tates h ad met t his goal, its greenhouse gas emissions for 2000 would h ave
been 1,675 MMTCE. However, U.S. emissions in 2000 were 1,921 MMTCE (not

23 Ibid., pp. 1.6-1.7. Note that the carbon trading assumption has been effectively mooted
since i t was not implemented i n 2002 as assume d i n t he study.
24 See t h e C l imate Action Report , Chapter 4; EIA, Analysis of the Climate Change
Technology Initiative , SR/ OIAF/ 99-1, avai l a bl e a t [ h t t p : / / www.ei o i a f / ar chi ve/
climate99/climaterpt.html ]; and EIA, Analysis of the Climate Change Technology Initiative:
Fiscal Y e ar 2001, SR/OIAF/2000-0 1 , A p r i l 2000, available at [ http://
climate/index.html ].

counting s inks). T h ese figures indicate t hat i n 2000, the n ation was ex ceeding its
UNFCCC greenhouse gas emissions commitment by 246 MMTCE, o r n early 15%.
If the United S tates had acced ed to the Kyoto Protocol, its greenhouse gases
emissions target for t he period 2008-2012 would h ave b een 5 times 93% of the 1,676
MMTCE baseline, or 1,559 MMTCE on average p er year for t he period. This
hypothetical go al would imply reductions e qual t o t he difference b etween the goal
and what would b e “business as u sual emissions” for the p eriod 2008-2012. Based
on the CAR projection t hat emissions will be 2,213 MMTCE in 2010, the average
annual reduction t hat would b e n ecessary for t h e U n i t e d S tates t o m eet the Kyo to
target of 1,559 MMTCE per year for 2008-2012 would b e 654 MMTCE per year, o r
about 30% below t he estimated l evel of “bus iness as usual” emissions. Higher t han
base case economic gr o w t h or lower p enetration o f energy-efficient t echnologies
would m ean that emissions would b e even h igher (and reductions necessary to meet
a goal like Kyoto great er). Slower economic growth, or fas ter penet ration of energy-
efficient t echnologies as s uggested by the 5 -Lab Study, would d ecrease emissions
(and hence reductions to meet a goal).
The P resident ’ s gr eenhouse gas initiativ e h as the goal o f reducing, through
voluntary activi t i es, t he intensity of net greenhouse gas emissions per unit o f
economic activity by 18% over t he nex t 10 years; this compares to a project ed
“business as u sual” d ecline i n i ntensity of 14% for t h e p e r i od — compared t o a
decline during t he 1990s of about 10% (see Table 3). According t o t he W h ite House
announcement, this go al means t hat t he current (2002) intensity of 183 metric tons
o f carbon emissions per million dollars of GDP would fal l t o 151 MMTCE p e r
million dollars of GDP in 2012 (see Fi gure 4 ). 25 At t h e ant i ci p at ed i n creased rat e of
intensity decline, total emissions would decline 100 M M T C E below “busines s as
usual” emissions (although t he absolute amount of emissions would continue to rise).
It is too early to assess progress toward the Administration’s goal of dimi n i s h i n g
greenhouse gas intensity.

25 Current data sugge sts t hat t he 2002 carbon intensity baseline may have dropped below 180
MMT CE (see Tabl e 3 ).

Figure 4 . G reenhouse G as Intensity:
President’s Initiative
Source: White House, Global Climate Change Policy Bo o k , F eb. 14, 2002, at
[http://yosemite.epa.go v / o a r / g lobalwarming. nsf/ Unique KeyLookup /SHS U5BNMAJ /$File/bush_ gc
These p roj ect ed em i ssi ons l evel s (and any implied reductions) are gross
estimates and do not take sinks into account (ex cept for the i ntensity projection). As
previousl y noted, t he baseline could b e revised, at l east s lightly. M ore important,
such projections depend on assumpti ons about economic trends as well as a b out
pol i cy act i ons at t h e l ocal , dom est i c, and i n t ernat i onal l evel s. However, what ever t h e
assum p t i ons, t he t rend i n t ot al em i ssi ons ex peri enced over t he past decade and
proj ect ed for t he nex t decade i s cl earl y upwa r d , w h i l e t h e UNFC C C go al was for
stabilization and the Kyoto Protocol calls for emissions levels of developed nations
Additional C onsiderations in
Assessing Possible R eductions
If one is concerned about assessing the implications of possible re d u c t i o n
requirements i n t he future, t wo f u r t h e r factors m ust b e considered. One is
sequestration, which removes C O2 from t he atmosphere, t hereby reducing gross
emissions. The second is a s eries o f p roposed trading m echanisms that could allow
a country to take credit f o r r e d u c t i ons it sponsors i n o ther countries. The United
States was a strong supporter o f i ncluding bot h t hese variables i n t he Kyoto P rotocol.
S e q u e s t r a t i o n c o u l d d i r ectly diminish a country’s red u c t i o n r eq u i r e m e n t ; t r a d i n g d o e s
not change a reduction requirement, but it could affect costs and who would actually
achieve the reductions.
Carbon Sequestration. Atmospheric greenhouse gas levels are affected not
only by emissions, but also by carbon sinks — p rocesses t hat rem ove and s equest er
carbon from t he atmosphere. Activities t hat affect sequestration i nclude farming and
forestry practices . For ex am ple, a positive n et growth of trees removes carbon from
t h e a tmosphere; clearing forests typically releases carbon. Table 1,“U.S.

Greenhouse Gas Emissions, 1990 -2001,” incl udes figures for carbon sequestration
from l and-use activities and forestry, which are t he difference b et w een “t otal
emissions” and “net emissions.”
T h e U N F C C C s t at es t h at s i gn at o r y n at i ons shall commit to “promote sustai n a b l e
management, and promote and cooperate in the conservation and enhancement, as
appropriate, o f s inks and reservoirs of al l greenhouse gases .. . , including biomass,
forest s a n d oceans as wel l as o t h er t errest ri al , coast al and m ari n e ecosyst em s”
(Article 4(1)(d)).
The Kyoto Protocol also would provide that sinks can be taken i nto account in
cal culating a nation’s emissions and its reduction obligation. “The net changes in
greenhouse gas emissions from s ources and removals by sinks resulting from d irect
human-induced l a n d -use change and forestry activities, limited t o afforestation,
reforestation, and d eforestation s ince 1990, measured as verifiable changes i n s tocks
... shall b e u sed t o m eet” t he 2008-2012 c o mmitments (Article 3(3)). In general,
t h en, a net i ncrease i n hum an-i nduced carbon sequest rat i o n from forest ry p ract i ces
between 1990 and 2008-2012 would b e s ubtracted from emissions during t he period,
thereby reducing t he amount of actual emissions that will have t o b e c u rtailed.
Conversely, net n egative s equestration fro m forestry p ractices would b e added t o t he
emissions that will have to be reduced.
J u st how this calculation would b e done is not prescribed in the P rotocol, and
disagreements on how much carbon sequestration could be counted toward a n ation’s
reduction obligations were debated t hrough s everal subsequent conferences. In J uly
2001, the S ix th Conference of Parties i n Bonn (COP6) agreed to limits on
sequestration activities t hat could be credited against the P rotocol’s reduction
requirements. Although t he United S tates chose n o t to participate i n t hese
proceedi n gs , t he C onference st at ed i n a foot not e26 that under t he methodology agreed
upon, the United S tates could t ake credit for net i ncreases of sequestration o f u p t o

28 million m et ric t ons per year.

Emi s sions Trading. Emissions trading, strongly supported by t he United
S t at es i n t h e K yo t o nego t i at i ons, d eri v es from t he pri n ci pl e o f econom i c effi ci ency
— t hat reductions, i f n ecessary, s hould b e achieved at t he lowest cost. Trading
mechanisms thus are des igned t o allow l ow-cost reductions to substitute for higher-
cost o n e s . T h e i dea i s t hat a country coul d achieve its reduction goal not only b y
reducing its domestic emissions, but also by reduci n g em i ssi ons el sewhere. Tradi n g
does not actually reduce a n ation’s reduction requ i r e m e n t , but it does allow i t t o
contract for and to count reductions elsewhere t hat are c h eaper to achieve than
The Kyo to Protocol provi d e s f or emissions trading m echanisms27 t h at can be
used to “supplement” domestic redu ct ions; t his o ffers the possibility that actual

26“Draft Decision on Implementation of t he K yoto Protocol on Climate Change,” adopted
in Bonn, Germany, J uly 23, 2001, footnote t o Appendix Z.
27K yoto Protocol, articles 4, 6, a nd 12; see a lso CRS Issue Brief IB97057, Global Climate
Change: M arket-Based Strategies to Reduce Greenhouse Gases.

domestic greenhouse gas reductions achieved b y a party t o t he Kyoto P rotocol will
b e l e ss than the party’s act ual commitment. S ome portion of t he reduct i o n
req u i rement could be s hifted el sewhere. The C linton Administration argued t hat
em i s s i on trading would be critical to U.S. compliance with Kyoto;28 a C linton
Administration economic anal ys is suggested that U.S. compliance costs would drop
from $193 per t on with no international emissions trading t o $23 per t on with gl obal
trading.29 COP6 agreed that there would b e n o quantitative limit on the amount of
credit a country could receive from t rading, but that domestic action m ust constitute
a s ignificant p art o f a nation’s reduction efforts.30 With n o q uantitative limit on
trading, any estimate of act ual domes tic reduction required t o comply with the Kyoto
Protocol, o r o f t he costs i nvolved, remains p roblematic — and is moot as long as the
United S tates declines to participat e i n t he Kyoto process.
The p recise numerical projections of greenhouse gas emissions (or o f p roposed
reductions) s hould b e v i e w e d as i ndicative (see Fi gure 3 ). They are l ess accurat e
than they appear, given the potential for revisions i n d ata and t he uncertainties of
projections. But in assessing the s tatus o f U.S. greenho u s e g a s emissions, t he
trendline for aggregate greenhouse gas emi ssions is clear: for the United S tates, the
overall trend i s up. None of the reviewed s cenarios using assumptions that diminish
emissions — l ow economic growth, putting off retirem en t of nuclear facilities,
accelerate d fostering o f energy-efficient t echnologies, the P resident’s voluntary
program t o reduce greenhouse gas intensity — reverses t he upward t rend in aggregate
greenhouse gas emissions by 2010. 31
Historical data show that the United S tates failed t o m eet its voluntary
commitment under t he UNFCCC for returning aggregate emissions at the end of the
1990s decade t o t he 1990 level. Any goal to reduce emissi o n s to or below 1990
l e v e l s w o u l d require the continuing upward t rend to turn down. Even with the
potential for sequestration and emissions trading t o reduce domes tic reduction
e f forts, a goal t o reverse greenhouse gas emissions trends would represe n t a n
ex traordinary t echnical and political challenge for U.S. energy and environmental

28Statement of J ane t Y e l l e n , Chair, President’s Council of Economic Advi sors, House
Committee on Commerce, Subcommittee on Energy and Power, March 4, 1998.
29For a discussion of the i mpact of emissi ons trading on c osts, s ee CRS R e port RL30285,
Global Climate Change: Lowering Cost Estimates through Emissions Trading — Some
Dynamics and Pitfalls , by Larry Parker.
30“Draft Decision on Implementation of t he K yoto Protocol on Climate Change,” adopted
in Bonn, Germany, J uly 23, 2001.
31T he “adva nced” s cenario of the “ Ne w 5-Lab Study” proj ects t he trend t urning downward