Energy Policy 32 (2004) 1499–1510

.

Comments on the Brazilian Proposal and contributions to globaltemperature increase with different climate responses—CO2 emissions

due to fossil fuels, CO2 emissions due to land use change

Luiz Pinguelli Rosa*, Suzana Kahn Ribeiro, Maria Silvia Muylaert,Christiano Pires de Campos

IVIG/COPPE/UFRJ—International Virtual Institute of Global Change of the Coordination of Post Graduation Programs in Engineering of the Federal

University of Rio de Janeiro, Bloco 1-Sala 129 Cidade Universitaria, Caixa Postal 68.501, CEP 21.945-970 Rio de Janeiro, Brazil

Abstract

This paper addresses the question of how to take into account the anthropogenic contribution to the increase of global

temperature, instead of being restricted to the Carbon emissions adopted in the Kyoto Protocol on responsibility sharing. It is

shown the sensibility of the results to the variation of the parameters from different authors used for simulating the climate response

based in the so-called Brazilian Proposal (BP).

It is also discussed the methodological and scientific aspects of the BP being discussed by an expert group coordinated by SBSTA/

UNFCCC and results of energy sector and land use change contributions by groups of countries.

r 2003 Elsevier Ltd. All rights reserved.

Keywords: Brazilian Proposal; GHG historical emissions; Climate change

1. Introduction

There is a current theoretical discussion motivated bythe Brazilian Proposal (BP) to the sharing of differentnations responsibilities in climate policy, based oncontributions to climate change instead of proposalscurrently based on annual emissions (Brazilian Propo-sal, 1997). The original Brazilian model has beenmodified (Meira and Miguez, 1998) to answer formercriticism, mainly in the evaluation of the contributionsto global temperature increase. After the revised version,there were four important events related to the theme:an informal expert meeting during the Buenos AiresConference of the Parties [COP-4], the expert meetingsheld in: (i) Cachoeira Paulista, Brazil, May 1999,(ii) Bonn, Germany, May 2001, and (iii) Bracknell,UK, September 2002. Some specific points, raised inthose meetings, are commented in the present paper.

According to the example of the BP, the pastcontributions from developed countries represent about84% of energy system emissions. During the preparationof a proposal for the Third Conference of Parties inKyoto (1997), in a meeting at the time of the Rio PlusFive Conference (1997), we have exchanged ideas withthe Brazilian Government team. It was concerned thequestion of how to take into account the contributionfrom different countries or groups of countries to theincrease of global temperature, instead of being re-stricted to their Carbon emissions in the current debateon responsibility sharing. A part of the ongoing process,there were further discussions on those points. Ourformer results were presented in three occasions beforethe Kyoto Conference: in the Conference on AIJ(Activities Implemented Jointly) at New Delhi inJanuary 1997, during the Rio Plus Five Conference inMay 1997 and in the International Energy Agency(IEA) Conference on GHG in Vancouver in June 1997,published in their proceedings (Rosa, 1997; Ribeiro andRosa, 1997; Rosa and Ribeiro, 1997). In those previousworks, we have developed a simple model to calculatethe relative contributions to temperature increase fromGHG emissions. It works well for simulations of

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*Corresponding author. Tel./fax: +55-21-2270-1586.

E-mail addresses: pr@eletrobras.gov.br (L.P. Rosa),

skr@pet.coppe.ufrj.br (S.K. Ribeiro), msmuylaert@ivig.coppe.ufrj.br

(M.S. Muylaert), ch.campos@uol.com.br (C. Pires de Campos).

URL: www.ivig.coppe.ufri.br.

0301-4215/04/$ - see front matter r 2003 Elsevier Ltd. All rights reserved.

doi:10.1016/S0301-4215(03)00121-6

different scenarios to give a feeling for the problem on aclear and transparent basis. Our approach provides avery transparent and simple way to compute thecontributions to global warming effect of historical,present and future emissions, by fitting the results ofcomplex models to simple analytical formulae withfew parameters (Rosa and Ribeiro, 2001). Ourmethod differs from that used in the BP because weuse analytical formulae instead of doing numericalintegration.The limitation of precision of such an approximation,

due to neglecting non-linearity, is discussed in thepresent paper. Data, especially on land use change andfirewood emissions as well as usual economy scenariosfor future emissions have higher uncertainty. Never-theless, estimates of such data are used as input incomplex models to compute CO2 atmospheric concen-tration and global temperature increase. In the present

work, we use available data of CO2 emissions due tofossil fuels and we use data calculated in our research(IVIG, 2002) due to land use change.The BP in Kyoto is resumed in Section 1, the current

debate on the BP is discussed in Section 2, where wecomment the main questions pointed out by critics.Section 3 introduces the important issue of climateresponse, one of the most relevants in the debate onthe BP.Section 4 presents the global contribution to CO2

(from energy sector) atmospheric concentration withdifferent approximations and Parameters (Figs. 1 and2). Section 4 also presents a simple and transparentapproximation used for fast calculation of globalcontributions (Fig. 3) to the climate change (based onCO2 emissions from energy sector, estimated by therevised BP), taking into account different parameters forthe climate response.

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0

25

50

75

100

125

150

175

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year

~(1)

^(2)

Fig. 1. Total contribution to CO2 (from energy sector) atmospheric concentration in approximations (1) and (2) with parameters (1) of Table 4.

0

50

100

150

200

250

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000Year

^(1)

^(2)

^(3)

Fig. 2. Total contribution to CO2 (from energy sector) atmospheric concentration in approximation (1) with parameters (1), (2) and (3) of Table 4.

0500

100015002000250030003500

Year

^(1)

^(2)

^(3)

^(4)

Fig. 3. Total CO2 (from energy sector) contribution to climate change with parameters (1), (2), (3) and (4) of Table 5 (adopting parameters of column

(1) of Table 4).

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–15101500

It is also showed, in Section 4, an exercise ofthe contribution to climate change using the parametersof the revised BP for climate response (column (1)of Table 5), due to historical fossil fuel and landuse change emissions based on new databases. Thedatabase for fossil fuel emissions has been takenfrom the US Oak Ridge National Laboratory, for theperiod 1750–1990 and the database for land use change(1700–1990) was established by our research (IVIG,2002).

These informations are organized in groups ofcountries. The CO2 contribution from the energy sectoris presented divided in Annex I and Non-Annex Icountries (Fig. 4). The CO2 contribution from land usechange is presented (Fig. 5) in groups of countriesorganized by OECD, Africa, Asia, Latin America.Besides, it is shown (Fig. 6) the result of bothcontributions, from the energy sector and the land usechange computed together, presented for Annex I andNon-Annex I countries.

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0

500

1000

1500

2000

2500

1751

1764

1777

1790

1803

1816

1829

1842

1855

1868

1881

1894

1907

1920

1933

1946

1959

1972

1985

GW

(G

t C

.yea

r)

Annex I

Non-Annex I

Fig. 4. Contribution to climate change of CO2 emissions due to energy sector and cement production from 1751 to 1998 (Source: IVIG, 2002).

0200400600800

10001200140016001800

1751

1768

1785

1802

1819

1836

1853

1870

1887

1904

1921

1938

1955

1972

1989

GW

(Gt C

.yea

r)

OECD

Asia

Latin AmericaAfrica

Fig. 5. Contribution to global warming of CO2 emissions due to land use change from 1751 to 1990 (Source: IVIG, 2002).

1751

1771

1791

1811

1831

1851

1871

1891

1911

1931

1951

1971

Non-Annex I

Annex I4000

3500

3000

2500

2000

1500

1000

500

0

GW

(Gt C

.yea

r)

Fig. 6. Contribution to global warming of CO2 emissions due to energy sector, cement production and land use change from 1751 to 1990

(Source: IVIG, 2002).

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–1510 1501

Section 5 presents the main conclusions of the paper,enphasizing the importance of the BP in the interna-tional scenario. The most important issue of the BP is topoint that annual emission is not the best measure ofclimate change effect neither the best measure to dealwith the responsibilities shares as well. The contributionto the climate change taking into account, among othersissues, the gases lifetimes, is an important step pointedout by the BP. This explains the international attentionabout the scientific and methodological aspects ofthe proposal by Brazil to distribute the burden of theemissions reductions. It is important to note that theconcept of the BP does not necessarily deal with anyspecific period of time. It can be applied to any certainperiod of time. The choice of the starting and endingdates implies in different share of responsibilities amonggroups of countries such as the Annex I and Non-AnnexI Parties to the Convention, what involves an importantaspect for the policy makers.

2. Brazilian Proposal for sharing responsibility based on

contributions to temperature increase—overview

The BP has addressed the relationship between theemissions of GHG and the increase of global meansurface temperature. It has also made an exercise inorder to choose a reduction target for each Annex Icountry. The choice was made in such a way as to assignrelative responsibilities to individual countries accordingto their contribution to climate change. It was used theexistent and available data for almost all countries atthat moment (1996/1997) which were exclusively relatedto CO2 emissions from the energy sector. For the samereason, it was chosen a certain time period (1990–2020)only as an example to explain the main content of theproposal: the importance of shifting the focus from‘‘emissions’’ to ‘‘temperature increase’’. This focuschanging is important because ‘‘temperature increase’’can be recognizable as a better indicator for the climate

change effect itself. It is also important becauseconsidering the indicator ‘‘temperature increase’’ resultsin accountability of responsibilities shares different fromthe responsibilities established by the ‘‘emissions’’indicator as pointed by the Kyoto Protocol. It is alsopossible to use it to assign relative responsibilitiescollectively to the Annex I countries, Non-Annex Icountries or to any other groups of countries.The intention of the BP was to achieve an agreed

model for computing the contribution of each countryto the increase of global temperature, starting from dataon annual emissions. The Proposal remains underdiscussion and it has been referred to the Scientificand Methodological Subsidiary Body (SBSTA) in the1997 Conference of Parties (COP) in Kyoto. In May1999, May 2001 and September 2002, expert meetings

discussed the scientific and methodological aspects ofthe proposal by Brazil. The main conclusions are: (i) theBP has sufficient scientific and technical basis foroperating the BP, (ii) different indicators to measurethe contribution to global warming give differentresponsibilities, and (iii) the simulation of differentmodels give values very similar when measuring thecontributions to global warming, proving one aspect ofrobustness of the proposal.Due to the absence of data at that time, the original

BP has not considered other important GHG such asCH4 and N2O and has not taken into account othersectors different from energy sector. Our research(IVIG, 2002) has produced new emissions database bycountries and we use some of our results in the presentpaper, to compare the CO2 emissions due to fossil fuelconsumption and land use change. The database forfossil fuel emissions by each country has been takenfrom the US Oak Ridge National Laboratory, for theperiod 1750–1990. The former version of the BP hasused k ¼ 1=140 years for CO2 concentration with aconstant factor C=0.5598 ppmv/PgC determined bylinear regression to fit the results of the MAGIC boxdiffusion model for the period 1990–2020, computedwith emissions from the IPCC-IS92a scenario. Analo-gously a factor was matched to the temperatureincrease, using the results of the MAGIC box diffusionmodel in the same period.In the revised BP a superposition of exponential

functions from the Bern Model has been used, instead ofthe single exponential. Besides, the time response ofclimate system has been included in the temperatureincrease calculation with a superposition of twoexponential functions.Ceiling and reduction targets were proposed to be

established for all the Annex I Parties in time periodsstarting from 1990 and taking the initial concentrationin 1990 to be equal to zero. The relative responsibility ofeach Annex I Party with respect to the Annex I Partiescollectively must be established for each period of timeby considering the respective concentration of GHG inthe atmosphere in the initial year of the period.The results of a simulation based on the BP are shown

in Table 1 (relative shares, based on the followingindicators: emissions, concentrations and temperatureincrease, of Annex I and Non-Annex I countries).Depending on the indicator utilized, the responsibilitiesof the two groups of countries, used as example, arequite different.Officially, the BP is the unique option for interna-

tional burden sharing being carried out bythe UNFCCC.1 At the moment, the international

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1Other approaches can be found in the literature, like the ‘‘Grand-

fathered Proposal’’ based on a hybrid per capita accountability; the

‘‘WRI’s carbon-intensity related proposal’’; the ‘‘Argentine proposal

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–15101502

community is starting to discuss the next commitmentperiod of the Kyoto Protocol and the proposal by Brazilcan help the discussions on share of responsibilities. Asthe BP presents a different option to share responsi-bilities among countries due to anthropogenic activities,shifting the focus of the debate from the emissions to thetemperature increase,2 it establishes a necessary newapproach to compute the emissions. It has to be takeninto account that the several greenhouse gases havedifferent lifetimes and characteristics and that theclimate system has a response for the gases.3

3. Current debate on the Brazilian Proposal

The BP has motivated the current scientific debate onits simplifications and assumptions to fit, in transparentand easy formulae for fast calculation, the complex timedependent relationship between emissions of GHG andglobal temperature increase (Enting, 1998; den Elzenet al., 1999a, b; Fuglevesdt and Berntsen, 1999; Meira,1999).A criticism to the BP arises from the difficulties that

such a complexity of climate system poses for definingresponsibility sharing, based on contributions to tem-perature increase calculated from emissions and atmo-spheric concentrations. The criticism on the originalproposal was recognized in the revised version of theproposal.

The original paper presented by Brazil in 1997proposed an approach for estimating the relative shareof responsibility for climate change, by different Annex Iparties, based on their contribution to the increase ofGlobal mean surface temperature over a certain periodof time. According to Meira (2001): ‘‘the proposal itselfwas for the use of an agreed simple climate model forestimating the temperature increase resulting fromemissions of different countries. As an illustration, the1997 assumed that the temperature increase is propor-tional to the time integral of the radiative forcing; a factwhich is only valid for very short time periods. Thisaspect of the model was later corrected. In addiction, thenon-linearities in the carbon cycle and radiative forcingwere included. As a consequence of the inclusion of non-linearities, the question of attribution of climate changeto different countries only could be addressed byadopting a differential, or marginal, approach’’. Allthe above changes are documented in the Report on theExpert Meeting held in Cachoeira Paulista, Brazil (denElzen et al., 1999a, b), ‘‘the primary focus of the expertmeeting was to identify issues relating to the scientificand methodological aspects of the BP, including thosethat need further consideration and areas of futurework’’.Regarding the revised version, we comment below the

main points argued. Most of them were discussed at theExpert Meeting of Cachoeira Paulista and considered inthe references already mentioned in this paper. Theconclusion of the meeting is that there is sufficientscientific and the technical basis for operating therevised BP and the methodology proposed by Brazil ofusing a highly parameterized, simple climate model, isconceptually sound given its purpose and when appliedon short time horizons. The revised methodology is amajor improvement compared to the original proposal,but still contains some important deficiencies: Thecarbon cycle sub-model needs to be improved to betterrepresent the non-linear response of CO2 concentrationsto a pulse emission. Such improvements must ensureadequate inclusion of terrestrial processes such as CO2

fertilization (den Elzen et al., 1999a, b). There are severalassumptions argued in the model used to support therevised BP, as follows.Emissions from fossil fuels prior to 1950 were

extrapolated in the BP from 1950–1973 data and sooverestimate industrialized countries contribution(Enting, 1998; den Elzen et al., 1999a, b). How-ever, there are many discrepancies among differentdatabases on early emissions, which are not quantita-tively so relevant for temperature increase as thoseafter 1950. In compensation the non-inclusion of bunkerfuels emissions in the BP model favours Annex Icountries. Anyway, we do not made such an extrapola-tion in our calculation, where we use Enerdata (Martin,1990).

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Table 1

Relative share of CO2 emissions (energy sector) and contributions to

atmospheric concentration and temperature increase

Annex I (%) Non-Annex I (%)

Emissions in 1990 75 25

Concentrations in 1990 79 21

Contribution to temperature increase

In 1990 88 12

In 2010 82 18

In 2020 79 21

Source: Brazilian Proposal (1997).

(footnote continued)

for index-linking targets to GDP’’; the ‘‘Triptych Proposal’’ of

University of Utrecht; the ‘‘Contraction and Convergence Proposal’’

of GCI (Global Commons Institute); the ‘‘Increasing participation/

Multi—stage approach Proposal’’; and others.2This implied the estimative of green house gases historical

emissions prior to 1990. Consequently, this information goes beyond

the National Communications being carried out at the moment.3This is illustrated by the sentences: ‘‘In a first approximation, the

dependence of the atmospheric concentrations upon the emissions over

a given period of time is proportional to the accumulation of the

emissions up to the year in question, taking into account that the older

the emission the smaller its effect on the concentration, due to the

exponential natural decay of the greenhouse gases in the atmosphere

with a different lifetime for each gas’’ (UNFCCC, 1997).

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–1510 1503

Emissions from land uses were not included also andthis kind of contribution is higher in Non-Annex Icountries in the present. Nevertheless, it was higher inAnnex I counties in the past. Besides, the uncertainty ishigh and emissions from food agriculture and cattlemust not be treated as those from deforestation or fromprivate cars in transportation. Land use emissions are aweak point of the emissions inventories even in thedeveloped countries.The calculation of the atmospheric concentration was

done with Bern model parameters from ocean carboncycle. It overestimates older emission of Annex I,because the dynamics of ocean is slower than theterrestrial one (Enting, 1998; den Elzen et al., 1999a, b).Nevertheless, the concentration calculated for 1990(370 ppmv) is only 5% higher than the IPCC value(355 ppmv) and the result for 2100 (715 ppmv) differsonly 0.7% from MAGGIC model (710 ppmv).The radiative forcing considered by the model of the

BP is proportional to the atmospheric concentrationfrom emissions. Therefore, it does not take into accountnon-linear saturation and overlap processes, due to thegrowing accumulation of CO2 in the atmosphere.Saturation and overlap are non-linear effects that reducewarming from present emissions and so its inclusionshall benefit Non-Annex I countries (Enting, 1998;

den Elzen et al., 1999a, b). However, it is due to earlyAnnex I emissions. Non-linear effects of radiative forcingcould reduce by about 20% Non-Annex I presentcontribution, in a first approximation to evaluate it bycomparing two hypothetical countries, one emittingfrom 100 years until now and the other growing theemission along the last 50 years (Enting, 1998).Temperature is calculated with time constant of

climate response higher in the Brazilian model than inother models. Therefore, the climate response becomestoo slow and it increases contribution of early emittersof Annex I. Other models use only fast response ofclimate response neglecting the slow component, whichis recognized to exist (den Elzen et al., 1999a, b). Thequestion of considering this slow component of climateresponse as relevant for climate policy is not a scientificsubject but a political issue to be discussed. From thispoint of view, the BP is extremely fruitful. Table 2summarizes the present discussion.There are two main issues related to the BP, the

scientific and the methodological issues. The scientificissues are related to the scientific aspects like robusttools, data, models and the methodological issues arerelated to indicators for contributions to global warm-ing, non-linearities and feedbacks, attribution dates,among others. In the expert meeting held in Cachoeira

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Table 2

Criticisms and comments on the Brazilian proposal calculation approach to CO2

Contributions In favour of Annex I In favour of Non-Annex I

(a) Emissions

From fossil fuels prior to 1950 extrapolated

from 1950–1973

Estimated emissions favours industrialized

countries

There are discrepancies among different data

Bunker not included Non-inclusion of bunker favours Annex I

Emissions from land uses are not included Contribution of Non-Annex I is higher in the

present

Contribution of Annex I higher in the past

High uncertainty and emissions from food

and agriculture and cattle must not be treated

as those from deforestation or from cars

(b) Concentration

Parameters from Bern model are of ocean

carbon cycle

Dynamics of ocean is slower than the

terrestrial one and overestimates older

emission of Annex I

The concentration calculated for 1990

(370 ppmv) is 5% higher than the IPCC value

(355 ppmv). The result for 2100 (715 ppmv)

differs only 0.7% from MAGGIC model

(710 ppmv)

(c) Radiative forcing

Non-linear effects not included Saturation and overlap reduce effects from

present emissions but it is due to early Annex

I emissions

Saturation and overlap non-linear effects if

included should decrease contribution from

Non-Annex I countries. Inclusion of non-

linear effects could reduce by 20% Non-

Annex I present contribution

(d) Temperature

Calculated with time constant of climate

response higher than in other models

The climate response in the Brazilian model is

too slow and it increases contribution of early

emitters

Other models use only fast response of climate

response neglecting the slow component

which is recognized to exist

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–15101504

Paulista, Brazil, 1999, it was concluded the existenceof sufficient scientific and technical basis for operatingthe BP.Some authors (den Elzen et al., 1999a, b) have made a

critical analysis of the two versions of the BP fromscientific and methodological points of view. Related tothe first version (UNFCCC, 1997) of BP, there are threemost important observations about BP:

(a) the study claims for the inclusion of other twogreenhouse gases, N2O and CH4, as BP calculatesonly the CO2 emissions due to energy sector;

(b) the study also claims for the inclusion of land usechange and forestry sectors and its contribution toglobal warming, as BP calculates only emissionsfrom fossil fuel;The BP authors’ arguments to these two points

can be clarified by the following affirmation:‘‘Different greenhouse gases can be included, withtheir respective constants of proportionality be-tween temperature (or sea-level rise) and theaccumulation of concentrations, and their indivi-dual affects added in terms of the resulting changein temperature or sea-level rise over the periodconsidered’’ (UNFCCC, 1997).

(c) the study considers an error to suggest that there isa long time delay between the contribution to CO2

concentrations and temperature increase, showingthat other models disagree of it.

Related to this question, there is a study developed byRosa et al. (see the webpage http://unfccc.int/issues/ccc.html), with the objective to show the robustness ofthe BP in such aspect. It is an exercise using differentparameters in a same climate response model tocompare the results in terms of time delay.Another theme discussed by the authors is the transfer

of ‘‘energy-efficient’’ technology from developed todeveloping countries; the starting year for calculatingemissions; the technical uncertainties related to estimat-ing land use changes, carbon content of biomass andterrestrial dynamics. Nevertheless, it seems that, in fact,the first three issues represent, even after the secondversion of BP with revision (2000), the most importantones in respect to decision-making implications.The expert meeting held in Bracknell, UK, 25–27

September 2002, had some important results in terms ofscientific and methodological issues. Besides, newsuggestions for different targets arose to be implementedin the next steps of the researches. The main issuesdiscussed and organized in a document (UNFCCC,2002) are listed below: ‘‘Indicators’’, ‘‘Non-linearitiesand feedbacks’’, ‘‘Databases’’, ‘‘Methods of attribu-tion’’, ‘‘Variation of attribution start and end dates’’,‘‘Evaluation Data’’, ‘‘Other forcing: aerosols and ozoneprecursors’’, ‘‘Different Scenarios’’ and ‘‘Display ofresults’’. The most important issues involve the inclusion

of the aerosols and some GEE precursors emissions inthe climate response effects, the creation of a stronghistorical data surveys in terms of gases emissions andthe importance of making efforts to turn the indicatorsof the climate change easier to be dealt with by thepolicy makers and non-specialists. They will be com-ment in the following sub-chapters:

3.1. Indicators

Indicators are used in the contribution to climatechange to measure the impact of each nation on theglobal warming. An ideal indicator should be close toimpacts, understandable and certain. BP defends the‘‘temperature increase’’ as the best indicator to under-stand the climate change because ‘‘the obvious choice ofa variable to measure climate change is the change inglobal mean surface temperature’’, since other globalvariables such as the time rate of change of the globalmean surface temperature and the rise in mean sea levelare derived from the change in global mean surfacetemperature (UNFCCC, 1997). The nature of suchchanges and the implications and usefulness as acriterion for burden sharing needs to be (i) close

resemble the impacts of climate change, (ii) understand-

able to scientists as well as the public, (iii) certainty

to calculate the indicator as well as robust4 and;(iv) backward discount to not give less ‘weight’ toemissions that occurred a long time ago.5

Some important climate change indicators identifiedby the experts in the Bracknell meeting were analyzed interms of usefulness for policy makers: emissions,concentration, radiative forcing, temperature increase,sea-level rise. Nevertheless, different indicators willresult in different attributions (UNFCCC, 2001), asthe adoption of annual emission as an indicator of shareof responsibilities, as in the Kyoto Protocol.6 Sea-levelrise, an indicator of climate change of considerable

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4Each step further down the cause–effect chain (i.e. from emissions

to concentrations or to radiative forcing and so on) introduces

additional uncertainty, due to an additional step and non-linearities in

the calculation.5For example, the concentration of methane today is not influenced

by emissions of methane 100 years ago. Because of the short lifetime of

methane in the atmosphere, these emissions have decayed almost

completely by now. The experts noted that it is uncertain whether such

‘backward discounting’ reflects the influence of emissions with respect

to damages. In addition, ‘backward discounting’ also affects the

certainty of the indicator, since information that dates further back is

usually more uncertain.6 It is important to highlight that the parties are presumed to have

control over their future annual emissions and the Convention

requirement is that Parties report annual emissions, given to a natural

tendency to compare the annual emissions of Parties and thus

implicitly to associate the emissions to the relative responsibilities in

inducing the climate change (UNFCCC, 1997). This is the present

approach of the Kyoto Protocol inducing the experts, policy makers

and mainly the non-experts a misinterpretation of climate change.

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–1510 1505

interest to many coastal countries, is closely related tochange in average global temperatures, but not allcountries are impacted by the sea-level rise, while thetemperature increase affects all. The most importantindicators are listed below (UNFCCC, 2002):

Cumulative emissions: The sum of annual emissionsfrom a source between a start and an end date. Thisindicator can only be applied for one greenhouse gas ata time. Effects of several gases cannot be compared.7

Concentrations: The effect of all emissions between astart and an end date on concentrations of the green-house gases in the atmosphere at the end date. Thisindicator can only be applied for one greenhouse gas ata time. Effects of several gases cannot be compared.

Integrated past concentrations with climate response:Integrating the increased concentrations due to emis-sions from a start date to an end date. This indicatorwas used in the calculations that accompanied theoriginal BP. (The revised proposal by Brazilian calcu-lates temperature increase, rate of temperature increaseand sea-level rise.) It is the first proxy for thetemperature increase. This indicator can also only beapplied for one greenhouse gas at a time. Effects ofseveral gases cannot be compared.

Radiative forcing (due to increased concentrations):the radiative forcing due to the increased concentrationsat the end date. The effects of different gases can becombined with this indicator.

Integrated past radiative forcing: Integrating theradiative forcing due to increased concentrations froma start date to an end date. This indicator is very similarto integrated past concentrations with climate response.It can be used to combine the effects of all gases.

Integrated future radiative forcing: The radiativeforcing due to the concentrations integrated from whenemissions end to a future date. It applies the concept ofglobal warming potentials (GWPs) to concentrations(instead of applying it to pulse emissions), takingexplicitly into account the unrealized effects that willoccur in the future after the gases have been emitted.

Temperature increase: The increase in global-averagesurface temperature due to emissions. The calculationtakes into account the effect of emissions between a startand an end date on concentrations and on radiativeforcing.8

Rate of temperature change: The rate of temperaturechange calculated as the derivative of the temperatureincrease.

Sea-level rise: The processes of thermal expansion ofwater and melting of ice. Because sea-levels increase veryslowly (in the order of thousands of years), the effectsseen today may be small compared to those that willoccur in the future, even if emissions stop.There is a ‘trade-off’ among indicators. On the one

hand, the indicator should be as close as possible to theactual impacts of climate change, i.e. damages, aspossible. It should therefore be further down thecause–effect chain. On the other hand, it shouldbe calculated with certainty and therefore be at thebeginning of the cause–effect chain. Table 3 lists theindicators and their characteristics as assessed byBracknell expert meeting.The main conclusions about indicators of the expert

meeting of Bracknell are that (i) the indicators fromconcentrations onwards do not include the effects of theemissions that will occur after the emission, sincegreenhouse gases stay in the atmosphere after they havebeen emitted for a period of time, the gases contribute toincreased concentrations, radiative forcing, increasedtemperatures and sea-level rise depending on theirparticular removal processes; (ii) it is possible tocombine various indicators into composite indicatorsin order to resemble more closely actual damages, butno one was suggested; (iii) the experts only considered

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7Rovere et al. (2002) propose the cumulative emissions over time as

indicator for measuring the responsibilities over the time, starting from

the year 1990 allowing growth targets relative to a business-as-usual

projection. According to Rovere et al. (2002), this would eliminate the

uncertainties and complexity of models, addressing some political

challenge of agreeing on data sets (especially non-CO2 and CO2

emission from land use change), preserving the original spirit of the BP

and more acceptable to the Parties.8 It is interesting to observe a study carried out by Wigley and Raper

(2002) as an example of the complexity of different opinions about the

temperature increase in the issue of climate change. According to the

summary made by the Center for the Study of Carbon Dioxide and

(footnote continued)

Global Change (www.co2science.org/journal/2003/v6n14c3.htm, on 3

April 2003) ‘‘In an attempt to quantify changes in the world’s climate

due to anthropogenic activities expected to occur between 1990 and

2100, the Second Assessment Report (SAR) of the Intergovernmental

Panel on Climate Change (IPCC) projected a mean global temperature

increase of 0.9 to 3.5�C under a ‘‘no climate policy’’ scenario that

assumes humanity does nothing to intentionally influence earth’s

climate in the interim; while the IPCC’s Third Assessment Report

(TAR) projected a mean global temperature increase of 1.4–5.8�C for

the same scenario. Wigley and Raper thus set out to answer the

obvious question raised by these dramatically different results: ‘‘Why

are the more recent projections so much larger?’’ The authors begin by

stating that the different results of the IPCC’s second and third

assessment reports arise from differences in the two major components

of the reports’ climate model calculations: (1) differences in emissions

scenarios, which are derived from what Wigley and Raper refer to as

‘‘storylines’’, and (2) differences in science, which one would hope

would be due to advancements in science. The authors then describe

these differences and how they altered the conclusions of the two

reports. With respect to the high-end warming of the two assessment

reports—which is what climate alarmists always cite in support of their

call for immediate implementation of draconian regulations to reduce

anthropogenic CO2 emissions—Wigley and Raper report that the

projected 1990–2100 warming rose by 2.3�C (from a value of 3.5�C in

the SAR to a value of 5.8�C in the TAR), but that advancements in

science were responsible for only 4% of that increased warming, which

translates to an additional temperature increase of a mere 0.1�C

between the time of the two reports. All the rest of the extra warming

projected in the TAR report (2.2�C out of 2.3�C) was thus the result of

nothing more than a scarier worst-case ‘‘storyline’’.

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–15101506

indicators evaluated at the global scale, regionalindicators also could be defined, but such calculationwould be extremely complex and more uncertain(UNFCCC, 2002).

3.2. Non-linearities and feedbacks

Several processes in the climate system are non-linearand include feedbacks. Consequently, the sum of theeffects of emissions from individual regions is not equalto the effect of all emissions together. Some non-linearities occur, for example, in the carbon cycle, theatmospheric chemistry, the relationship between con-centration of CO2 and radiative forcing, the relationshipbetween radiative forcing and temperature increaseand the relation between temperature increase and sea-level rise.Feedback processes will lead to non-linearities when

the feedback is strong. Even when the feedbacks behavelinearly, they introduce the same methodological prob-lems as non-linearities. The experts felt that at thisstage it is difficult to determine the relative significanceof the non-linearities and feedbacks for the attributioncalculation.Due to the non-linearities and the feedbacks, it can be

observed the following aspects (UNFCCC, 2002):

* Emissions at different points in time will havedifferent effects. For example, because of the non-linearity in the calculation of radiative forcing fromconcentrations, the additional radiative forcing dueto additional CO2 concentration is a quarter lowertoday (due to higher CO2 concentrations) than it wasat the beginning of industrialization (when the CO2

concentration was lower).* The effect of emissions of individual sources may

depend on emissions of other sources. For example,the effect of CO2 emissions today is different becauseemissions have occurred in the past.

* These issues were also discussed in the expert meetingheld in Cachoeira Paulista, Brazil, 1999 (den Elzenet al., 1999a, b). The original BP and some participat-ing experts used simplified linear models. Therepresentation of the climate system is less realistic,yet the attribution is simple, because emissions ateach point in time are considered as having the sameeffect. After that meeting, there was the revision ofthe BP in which the period taken into account wasreduced to solve this problem. In general, on shorttime scales, linear models are more reliable than onlonger time scales.9

* All models confront the same difficulty of theuncertainties and non-linearities. It should be com-mended here the CICERO, Norway; CSIRO, Aus-tralia; DEA-CCAT, Denmark; ECOFYS, Germany;Hadley Center, United Kingdom; GRAPE andRITE, Japan; LBNL, UIUC and ISAM, UnitedStates of America; RIVM, the Netherlands; andNIWA, New Zealand. There are two models inBrazil: the first one is the BP itself and the other is theintegrated past emission with climate response beingconducted by the IVIG/COPPE/UFRJ.

4. The climate response problem

According to several expertise, the approach of theBP needs to be improved to consider some non-lineareffects such as climate response. A first step, startingfrom the original BP, was the inclusion of an exponen-tial decay factor in the integration to calculate thewarming effect. The crucial parameter is the decayconstant to be used in the exponential function. Thereare different values in discussion, all of them arising

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Table 3

Indicators for attribution to climate change and their characteristics

Indicator Close to impacts Understandable Certain Backward discounting

Cumulative emissions — 4 3a —

Concentrations 1 4 2.5 3

Integrated concentrations with climate response 1.5 — 2.5 2

Radiative forcing (due to increased concentrations) 2 2 2 3

Integrated past radiative forcing 3 — 2 2

Integrated future radiative forcing 3.5 — 2 3

Temperature increase 4 4 1.5 2

Rate of temperature change 4 2b 1 ?

Sea level rise 4 4 0.5 1

Source: UNFCCC (2002).aThe certainty depends on the certainty of the emissions.bWhile the indicator ‘rate of temperature change’ is well understandable, the attribution of positive and negative contributions to the rate of

temperature change is more abstract.

9According to Pinguelli et al. (unfccc.int/issues/ccc.html) the

variation of the parameters used to simulate the climate response do

not change the main conclusion of the BP.

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–1510 1507

from more sophisticated calculations. Enting (1998)suggest the time constant 37 years (see Table 5), fromthe work of Hasselmann et al. (1993). In the InformalMeeting on the BP during the Conference of Parties(COP 4) at Buenos Aires other values have beensuggested. In the Expert Meeting of Cachoeira Paulista,in May 1999, different climate responses have beendiscussed (den Elzen et al., 1999a, b).The question is deeper than knowing the best

parameters to describe the climate response in a policymaker approximation. In spite of the heavy advancedcomputation for modelling atmospheric circulationcoupled to ocean in global warming simulations, thereare constraints in models (Hasselmann et al., 1993).The global mean temperature near the earth surface

can be studied through a response function to aradiative forcing impulse, provoked by the instanta-neous variation in the GHG atmospheric concentration,due to a pulse emission. The system relaxes toequilibrium and the simplest approximation forthis response is an exponential decay with a single timeconstant. There are different values for the timeconstant as pointed out in Section 5. The responsefunction can be represented through a superposition ofnormal modes, as usual in solutions of differentialequations. A two exponential functions sum is thesimplest case of combination of response functionssuperposed. Different time constants have been given inthe literature with a broad range of values (Cubash,1992; Hasselmann et al., 1993).Nevertheless, all those approximations are limited by

the high residual non-linearity for large response times.The response function is a proper tool for linear system,but it is not enough to explain the non-linear dynamics.There is not consensus on how to include non-lineareffects in the context of a simplified policy maker model.The warming effect of the emitted gas is related to its

permanence in the atmosphere during a period, where itsmolecules absorb partially the thermal radiation fromthe Earth surface to the external space, blocking the exitof heat and increasing the average temperature nearthe Earth surface. The radiative forcing, linked to theatmospheric gas concentration, drives this effect. Thenon-linear characteristic of the system complicates thisrelationship.We have used different alternative time constants for

calculating the contributions to global warming fromAnnex I and Non-Annex I CO2 emissions, to check thesensitivity of the results. Differently of the BP, we do notcalculate the global temperature increase, but insteadthe contribution to global warming, as the integration ofthe atmospheric concentration from the gas emissions. Itis an ingredient for calculating the global temperatureincrease (Rosa and Ribeiro, 2001).We define the contribution to climate change W ðtÞ;

expressed in mass of the gas multiplied by time

(Gt C yr), as the integration of the atmosphericconcentration of the emitted gas along the time, with aweight function in the integrand to simulate the climateresponse. Due to negative feedback of the climatesystem, there is a kind of saturation of the warmingeffect represented by W ðtÞ and so, of the globaltemperature increase, which is related to this function.It is possible to simulate the climate response by asuperposition of exponential decay functions also withdifferent decay constants. So

W ðtÞ ¼X

i

Xj

bjgiWijðki;wj ; tÞ; ð1Þ

where

Wijðki;wj;tÞ ¼ e�wj t

Z t

0

d t0e�ðki�wjÞt0Z t0

0

d t00ekit00cðt00Þ; ð2Þ

cðtÞ is the emission in the time t; ki and bi are,respectively, the exponential decay constants and thefactors in the superposition of exponential functions ofthe Bern Model for the atmospheric concentration ofthe emitted gas (Table 4); wi and gi are, respectively, theexponential decay constants and the factors in thesuperposition of exponential functions for simulatingthe climate response (Table 5).

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Table 4

Different parameters for the decay of CO2 atmospheric concentration

(1) (2) (3)

1=ki bi 1=ki bi 1=ki bi

Years Years Years

330 0.216 6.9 0.30036 140 1

80 0.392 71.1 0.34278 — —

20 0.294 815.7 0.35686 — —

1.6 0.098 — — — —

(1) Bern model parameters used in the revised Brazilian Proposal

(1998).

(2) Bern model parameters (IPCC, 1995).

(3) Single exponential used in the former Brazilian Proposal.

Table 5

Different parameters for the time response of climate

(1) (2) (3) (4)

1=wi gi 1=wi gi 1=wi gi 1=wi gi

Years Years Years Years

20 0.634 3.66 0.574 1.6 0.585 37 1

990 0.366 120 0.426 58 0.415 — —

(1) Revised Brazilian Proposal.

(2) Meta image, quoted in Elzen et al. (1999,a b).

(3) Image 2.1, Elzen et al. (1999,a b).

(4) Enting (1998) from Hasselmann et al. (1993).

L.P. Rosa et al. / Energy Policy 32 (2004) 1499–15101508

5. Global contributions to concentration considering

different parameters for the decay of CO2 atmospheric

concentration and global contributions to global warming

considering climate response

For comparison, we have calculated the atmosphericconcentration and the global warming contributionsfrom historical World emissions (CO2 from energysector) for different model approximations. The atmo-spheric concentration is calculated (Fig. 1) by using: (1)continuous emission integrated with a linear approx-imation, which has been done in previous paper (Rosaand Ribeiro, 2001); (2) discrete annual emissions asusual. The curves present similar results. We show also(Fig. 2) the results with the atmospheric concentrationdescribed trough different superposition of exponentialfunctions corresponding to different time constants,including those of Bern Model (Table 4).Comparison of Results for Total Past Contributions

using different approximations and parameters.As it is possible to see in Fig. 1, there is good

agreement between the two approximations (at first, thecontinuous emission integrated with a linear approx-imation, which has been done in previous paper, Rosaand Ribeiro, 2001; and second, the discrete annualemissions as usual). The same is not true in Fig. 2, wherethe single exponential with 1=ki ¼ 140 years gives aresult in complete disagreement with the Bern Model.We use the Bern Model parameters of column (1) ofTable 4, in our computations of climate change W ðtÞ(Fig. 3), where the four groups of parameters for timeresponse presented in Table 5 are compared. In thecalculation of W ðtÞ we have checked (Fig. 3) differentexponential functions for simulating the climate re-sponse once it is not clear, until now, what is the besttime constant to fit of the climate response (Table 5).The result for W ðtÞ is higher when we use the parametersof calculus (1) of Table 5.To address the question of the introduction of new

gases emissions database, we are developing a projectwhich has some results presented below. In Fig. 4, it canbe observed the historical (1751–1998) contribution toglobal warming of the Annex I and Non-Annex I Partiesto global warming only related to energy sector. For thisexercise, it was considered the parameters of the BERNmodel (column (1) of Table 4) and the parameters forclimate response from the revised BP (column (1) ofTable 5).In 1998, the 1751–1998 contribution to climate change

related to the energy sector of the Annex I Partieswas responsible for 87% (2.097Gt C yr) of the worldenergy sector contributions, and the contributionof Non-Annex I Parties to climate change was 13%(314Gt C yr).Fig. 5 shows the contribution to global warming of

CO2 emissions due to Land Use Change from 1751 to

1990 by the following groups of countries: OECD, LatinAmerica, Africa and Asia. For the period taken intoaccount, the contribution to global warming of theOECD countries (1650Gt C yr) corresponds to 49.3%of the world land use change contribution to climatechange, Asia 22.4% (750Gt C yr), Africa 11.9% (400GtC yr) and Latin America 16.4% (550Gt C yr).Fig. 6 illustrates the contribution to global warming

from CO2 emissions of the Annex I and Non-Annex IParties due to the Energy Sector and Land Use Changecomputed together from 1751–1990. The Annex IParties represent 64.14% of the world energy sectorplus land use change contribution to climate change(3670Gt C yr) and the Non-Annex I Parties represent35.85% (2051Gt C yr).

6. Conclusion

The Brazilian Proposal has an important role in theinternational scenario. The most important issue of theBP is to point that annual emission is not the bestmeasure of ‘‘climate change effect’’ neither the bestmeasure to deal with the responsibilities shares as well.The contribution to the climate change taking intoaccount, among others issues, the gases lifetimes, is animportant step pointed out by the Brazilian Proposal.This explains the international attention about thescientific and methodological aspects of the proposalby Brazil to distribute the burden of the emissionreductions.It was used our model (Rosa and Ribeiro, 2001),

described in the chapter 3, to estimate the contributionto climate change from CO2 emissions of the Annex Iand Non-Annex I Parties due to the Energy Sector andLand Use Change computed together (Fig. 6), in thechapter 4. It can be observed that Annex I countriespresents higher contribution than Non-Annex I coun-tries considering the period from 1751–1990.It is important to note that the concepts of the

Brazilian Proposal does not necessarily deal with anyspecific period of time. It can be applied to any period oftime different of the one, used as an example, in theofficial document of the proposal. The choice of thestarting and ending dates implies in different share ofresponsibilities among groups of countries, such asOECD, continents, or the Annex I and Non-Annex IParties to the Climate Convention, what involves animportant aspect for the policy makers.The Brazilian Proposal highlights another important

political issue in the climate change debate: the existentlong time vision of the cause–effect relation between theanthropogenic emission and the climate change effectitself. It reminds the development processes taken by theworld and their respective consequences. In this sense,Brazilian proposal can be considered as a starting point

ARTICLE IN PRESSL.P. Rosa et al. / Energy Policy 32 (2004) 1499–1510 1509

(for the second period of compromises, in case KyotoProtocol will be confirmed for the first period as well)for the involvement of developing countries and for thefulfilment of the developed countries’ commitment toGHG abatement, looking for a different pathwaydevelopment.

Acknowledgements

The authors are grateful to the National Council ofResearch (CNPq), the Ministry of Science and Technol-ogy (Global Climate Change Department), the Founda-tion for Research Support of Rio de Janeiro (FAPERJ)and the researchers of International Virtual Institute onGlobal Change (IVIG), specially, Leonardo Cardoso.

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