Radiative Forcing Due to AnthropogenicGreenhouse Gas Emissions from Finland: Methodsfor Estimating Forcing of a Country or an ActivitySUVI MONNI*RIITTA KORHONENILKKA SAVOLAINENVTT ProcessesP.O. Box 1606FIN-02044 VTT, Finland

ABSTRACT / The objective of this study was to assess theradiative forcing due to Finnish anthropogenic greenhouse gasemissions in three scenarios. All the Kyoto Protocol gases,i.e., CO2, CH4, N2O, and fluorinated gases, were included.The calculations showed that forcing due to Finnish emissionswill increase in the case of all gases except methane by theyear 2100. In 1990, radiative forcing due to Finland’s emissionhistory of all Kyoto Protocol gases was 3.2 mW/m2, of which71% was due to carbon dioxide, 17% to methane, and therest to nitrous oxide. In 1990 the share of fluorinated gases

was negligible. The share of methane in radiative forcing isdecreasing, whereas the shares of carbon dioxide and of flu-orinated gases are increasing and that of nitrous oxide re-mains nearly constant. The nonlinear features concerning ad-ditional concentrations in the atmosphere and radiative forcingdue to emissions caused by a single country or activity arealso considered. Radiative forcing due to Finnish emissionswas assessed with two different approaches, the marginalforcing approach and the averaged forcing approach. Theimpact of the so-called background scenario, i.e., the sce-nario for concentration caused by global emissions, was alsoestimated. The difference between different forcing models atits highest was 40%, and the averaged forcing approach ap-peared to be the more recommendable. The effect of back-ground concentrations in the studied cases was up to 11%.Hence, the choice of forcing model and background scenarioshould be given particular attention.

Climate change can be seen as one of the mostserious environmental risks to humankind. It has aglobal character because the greenhouse gas emissionsare mixed to the whole atmosphere, and its develop-ment both at global and regional/local scales dependsmainly on the global total emissions rather than onlocal or regional emissions. The United Nations Frame-work Convention on Climate Change (UNFCCC) andthe Kyoto Protocol made under it can be regarded asthe world’s collective effort to mitigate climate change.In addition to carbon dioxide (CO2), which is the mainanthropogenic greenhouse gas, the Kyoto Protocol alsocovers anthropogenic emissions of methane (CH4), ni-trous oxide (N2O), and partly and totally fluorinatedhydrocarbons (HFCs and PFCs) and sulfur hexafluo-ride (SF6). Because practical emission control policiesare the responsibility of individual countries, some in-dex to measure the impact of individual countries onclimate change is needed. Usually the responsibilitiesof single countries or activities in climate change are

described using greenhouse gas emissions expressed,e.g., in CO2 equivalents. This approach is also used inthe burden sharing of the Kyoto Protocol. However,although this is quite simple and practical, it does nottake into account emission histories and slow removalof greenhouse gases from the atmosphere leading toaccumulation of gases. In fact, anthropogenic climatechange and its mitigation contain many inertial fea-tures of both natural and socioeconomic types. Naturalinertial phenomena are caused, e.g., by slow removal ofgreenhouse gases from the atmosphere and particularlyby the thermal capacity of oceans. Socioeconomic iner-tia is associated with investment stock (buildings, powerplants, infrastructure, etc.), population, consumptionpatterns, and government structures.

Greenhouse gas concentrations in the atmosphereincrease due to anthropogenic greenhouse gas emis-sions. Greenhouse gases are removed from the atmo-sphere in various ways and time scales depending, e.g.,on their reactions with other gases in the atmosphere.Carbon dioxide is the only anthropogenic greenhousegas that circulates between the atmosphere, oceans,and biosphere. The most significant carbon fluxes oc-cur between the atmosphere and oceans and betweenthe atmosphere and the terrestrial biosphere. Methane(CH4) and the partly fluorinated hydrocarbons (HFCs)

KEY WORDS: Greenhouse effect; Radiative forcing; Global Warming;Marginal forcing approach; Kyoto Protocol

*Author to whom correspondence should be addressed; email:Suvi.Monni@vtt.fi.

DOI: 10.1007/s00267-002-2865-6

Environmental Management Vol. 31, No. 3, pp. 401–411 © 2003 Springer-Verlag New York Inc.

are primarily removed from the atmosphere by reac-tions with hydroxyl radical (OH). Aerobic soils are alsoa minor sink of methane. Nitrous oxide (N2O), fullyfluorinated hydrocarbons (PFCs) and sulfur hexafluo-ride (SF6) are removed from the atmosphere by pho-todissociation (IPCC 2001).

Radiative forcing is defined as the perturbation tothe net irradiance at the tropopause after allowing thestratospheric temperature to readjust to radiative equi-librium (IPCC 1995). It can be used as an index de-scribing the greenhouse impact of a country or anactivity when studying the main dynamic features ofglobal warming. Radiative forcing can also include forc-ing agents of various types, such as several greenhousegases and changes in the planetary albedo due to par-ticles or vegetation changes. Globally averaged radiativeforcing was assessed, e.g., by the IntergovernmentalPanel on Climate Change (IPCC) for global emissionhistories and scenarios (IPCC 2001). It has also beenused to describe the greenhouse impact of some activ-ities, such as peat-fuel-based energy production (Up-penberg and others 2001, Savolainen and others 1994),forestation projects (Korhonen and others 2001), oraviation (IPCC 1999).

In the United Nations Framework Convention onClimate Change it is stated that countries have “com-mon but differentiated responsibilities” in mitigatingclimate change. This is usually interpreted as meaningthat industrial countries should bear the main respon-sibility of emission reductions. In the climate negotia-tions, Brazil has proposed that the responsibility foremission reductions should be based on the tempera-ture increase caused (UNFCCC Secretariat 1997). Thiscan be approximated by the radiative forcing integral,if the temperature increase adjustment term is omittedas has also been done in GWP calculations. The revisedversion of the Brazilian proposal (Filho and Miguez2000) includes particularly the time-dependence of thetemperature increase and mean radiative forcing,which was not included in the original proposal. Whenconsidering emissions as proposed by Brazil, historicalemissions would also be taken into account when shar-ing the burden of emission reduction, leading to alower burden for developing countries because of theirshort emission history.

After the Brazilian proposal, den Elzen and Schaef-fer (2000) made comparisons between differentchoices for burden sharing between Annex I and non-Annex I countries and also between some smaller re-gions using sharing methods for radiative forcing pre-sented by Enting (1998), which is discussed further inthe Methods section. The main conclusions of denElzen and Schaeffer (2000) were as follows: taking into

account CO2 emissions due to changes in land use inaddition to fossil fuel CO2 emissions increases the effectof non-Annex I countries on temperature increase,because most of the current land use emissions occur indeveloping regions. Including not only CO2 emissionsbut also other anthropogenic greenhouse gas emissionsincreases the contribution of developing regions evenmore. When taking the nonlinear behavior of radiativeforcing (and thus, temperature increase) into account,the share of developing regions decreases (den Elzenand Schaeffer 2000). Enting (1998) analyzed the attri-bution of carbon dioxide concentration and radiativeforcing, especially in the case of land use change. Theproportional contribution from land use change toradiative forcing of all anthropogenic greenhouse gasesis greater than the proportional contribution to carbondioxide concentration, because emissions from landuse change have occurred mainly during the periodwhen carbon dioxide concentrations were lower thanthey are today (Enting 1998).

The objective of this paper is to assess the radiativeforcing impact caused by the anthropogenic emissionsfrom Finland. Assessments were made using the infor-mation published in the Third Assessment Report ofthe Intergovernmental Panel on Climate Change(IPCC 2001) on greenhouse gas forcing properties. Atthe same time an approach was developed to considerhow the non-linear features of dependencies betweenemissions and concentrations and between concentra-tions and radiative forcing can be considered in thecase of a country or an activity that causes a fraction ofthe global emissions only. The so-called marginal cal-culation, which takes into account the saturation effect,is different from that of Enting (1998) but is similar tothat used in IPCC (1999) report “Aviation and theGlobal Atmosphere.”

Methods

The model used in this study to estimate greenhousegas concentration and radiative forcing is called REF-UGE2, and it is based on an older computer modelREFUGE described by Korhonen and others (1993).The model calculates additional concentrations ofgreenhouse gases in the atmosphere due to given emis-sion histories or scenarios and the consequent radiativeforcing caused by increased concentrations. When cal-culating forcing of a country or of a single activity, themodel takes into account the background concentra-tion caused by global emissions, and radiative forcingcan be calculated using two alternative models, themarginal forcing approach and the averaged forcingapproach. The functions describing the relation be-

402 S. Monni and others

tween atmospheric concentration and radiative forcingare based on (IPCC 2001), and are presented in Ap-pendix 1.

Removal of greenhouse gases from the atmosphereis modeled with pulse–response functions, which de-scribe the time behavior of a unit pulse emission to theatmosphere. The function describing removal of car-bon dioxide from the atmosphere to the oceans isbased on the pulse–response model presented byMaier-Reimer and Hasselmann (1987). It is a superpo-sition of five exponentials with different relaxationtimes depending on concentration level and takes intoaccount only the transfer of carbon dioxide from atmo-sphere to oceans (Maier-Reimer and Hasselmann 1987).Pulse–response functions are presented in Appendix 1.

Carbon fluxes between the atmosphere and the ter-restrial biosphere are an important part of the naturalcirculation of carbon. One strategy in the modeling isto express explicitly the direct source and sink termsdue to human activities, such as deforestation and af-forestation and to describe the rest of the biosphericimpact by fitting the pulse–response function to ac-count for these as well. This method has been used, forexample, by Enting and others (1994) and Joos andothers (1996). Another way, which was adopted in thisstudy, is to consider all carbon fluxes between theatmosphere and the terrestrial biosphere as externalinput terms, sources or sinks, to the model. This isbased on the assumption that the additional atmo-spheric CO2 concentration due to an emission to theatmosphere causes an increased transfer to the ocean,but the additional atmospheric concentration will notchange the flux of CO2 to the terrestrial biosphereexcept for the small impact due to CO2 fertilization(which is also known relatively inaccurately). The car-bon fluxes between atmosphere and terrestrial bio-sphere depend mainly on other factors such as climateand direct human activities.

Pulse–response functions of methane, nitrous oxide,and the fluorinated greenhouse gases are functionswith only one exponential depending on the effectiveatmospheric lifetime of the gas. Only the fluorinatedgreenhouse gases (HFCs, PFCs and SF6) have constantlifetimes. By contrast, the lifetimes of methane andnitrous oxide are dependent on the concentrations ofthese gases in the atmosphere. The concentration ofmethane has a positive feedback to its atmosphericlifetime, and therefore increasing concentration ofmethane leads to decreasing removal of methane fromthe atmosphere. For nitrous oxide, the effect is theopposite, although not as significant as in the case ofmethane (IPCC 2001). These feedbacks have beentaken into account in the REFUGE2 model by changing

lifetimes according to global atmospheric concentra-tion as described in Appendix 1.

An increased greenhouse gas concentration leads toincreased radiative forcing, because thermal radiationemitted by the Earth is partly trapped by greenhousegases. Every greenhouse gas absorbs radiation in arange of wavelengths, and globally averaged radiativeforcing is an integral over all the wavelengths. Whengreenhouse gas concentrations increase sufficiently, allradiation of a particulate wavelength is trapped, leadingto saturation of radiative forcing (Wuebbles and Ed-monds 1991). Partial saturation of radiative forcing isimportant for CO2, CH4, and N2O, but not for the fluor-inated gases, the concentrations of which are very low.

In this study, the contribution of Finland to globalradiative forcing is considered. Two possible ap-proaches in calculating radiative forcing caused byemissions due to a single country or activity were con-sidered in the REFUGE2 model. One of the methods iscalled here the marginal forcing approach. A similarmarginal forcing approach is used, for example, inChapter 6 in the report “Aviation and the Global At-mosphere” (IPCC 1999). The marginal forcing ap-proach used takes into account the saturation effect sothat emitters who come last end up with lower radiativeforcing, because some saturation has already occurred.The method estimates forcing on the basis of concen-tration contributions �CACT, for which differential ra-diative forcings are applied. The marginal contributionof a country or an activity can be calculated usingequation 1.

�FACT�CACT�EACTHIST,SCEN�� � �CACT�EACT

HIST,SCEN�

*d��FGLOB �CGLOB �EGLOB

HIST,SCEN���

d �CGLOB �EGLOBHIST,SCEN��

(1)

where �F denotes change in radiative forcing, C notesthe concentration of the greenhouse gas considered inthe atmosphere, �C the change in concentration, and Ethe emissions of the greenhouse gas considered. Thesubscript ACT denotes the activity or region (in thiscase Finland) and subscript GLOB is global. The super-script HIST, SCEN denotes dependency of a selectedemission history or scenario.

The marginal approach generally under- or overes-timates impacts, depending on the functional form ofimpact versus, e.g., concentration. The marginal forc-ing approach used in this study (equation 1) underes-timates the forcing effect of a contribution due to thesaturation effect of radiative forcing. The problem withthe marginal approach is that if all contributions areestimated using the marginal approach, they cannot besummed up.

Radiative Forcing Due to Finnish Emissions 403

Enting (1998) also allocated radiative forcing ac-cording to changes in corresponding concentrations.This formalism is slightly different from equation 1because it considers marginal forcing so that contribu-tions can be summed up. Enting’s (1998) equation formarginal forcing is

FACT�C�t�� � �t

�FGLOB

�CGLOB

�CACT

�tACTdt (2)

In this study (equation 1), the contribution of a countryor activity was estimated on the basis of final contribu-tions (i.e., on the basis of contribution at the end of theconsidered time interval). This differs from the ap-proach of equation 2, which evaluates warming contri-butions during the considered time interval. When al-location is performed on the basis of finalconcentrations (equation 1), warming, e.g., due to tem-porarily high CH4 concentrations is not considered tocause warming for a longer time span than that of theconcentration increase.

Another method is to divide global forcing up inproportion to the additional atmospheric concentra-tions caused by different countries or activities. Thismethod is called here averaged forcing approach and isdefined by equation 3.

�FACT�CACT�EACTHIST,SCEN�� � �FGLOB�CGLOB�EGLOB

HIST,SCEN��

*�CACT�EACT

HIST,SCEN�

CGLOB�EGLOBHIST,SCEN� � C0

(3)

where C0 denotes undisturbed concentration (the con-centration during the preindustrial period) of the gas.

In both methods used in this study (equations 1 and3), a scenario for global emissions must be chosen,because global emissions affect the so-called back-ground concentration in the atmosphere. When globalatmospheric concentration is increasing, the share of asingle country decreases. The choice of a correspond-ing global and regional scenario is not at all unambig-uous. The effect of the background scenario was alsostudied in the case of Finland.

The REFUGE2 model also takes into account theslowing of removal of CO2 and methane from the at-mosphere due to increased concentration. When theatmospheric concentration increases, the additionalconcentration caused by a country as a function of timealso increases due to slowing removal of the gas fromthe atmosphere. Thus the effect of background con-centration on the additional concentration caused by acountry is contrary to the effect of background concen-tration on radiative forcing. However, the saturation of

radiative forcing is a stronger phenomenon and, as anet effect, higher background concentration leads tolower radiative forcing due to a country or an activity.

Scenarios and Results

For the assessment of the radiative forcing caused byFinland, three emissions scenarios are used. Two ofthem, KIO1C and BAUC, are based on the scenarios ofthe National Climate Strategy for Finland until the year2020, and after that they are linear extrapolations. Onescenario, TechnoC, is based on the book “Energy Vi-sions 2030 for Finland” (Kara and others 2001) untilthe year 2030 and is also a linear extrapolation there-after. In the KIO1C scenario it is assumed that Finlandwill achieve the national target of the Kyoto Protocol in2010, after which the emissions will remain constant.The control of emissions is based on policies on in-creased use of renewables and energy conservation andon limiting of coal-fired condensing power productionby increasing the use of natural gas. Historical emis-sions of Finland have been taken from (Lehtila andTuhkanen 1999) until the year 1990, and after thataccording to Finland’s Third National Communicationto UNFCCC (Sarkkinen and others 2001).

In the BAUC (business as usual) scenario, no newmeasures for emission reduction or energy saving areassumed. In the TechnoC scenario, strict environmentalconstraints and rapid development in technology areassumed. The emission trends from 1990 to 2100 arerather similar to the trends in the SRES (IPCC 2000)scenarios A2, B1, and B2 for Annex I countries. Thecorresponding scenarios for Finland are KIO1C for B2,BAUC for A2, and TechnoC for B1. When comparingper capita emission reductions of B1 and TechnoC, itcan be seen that the emission reductions of TechnoC

would not be sufficient for the goal of B1, i.e., stabili-zation of CO2 concentration. In any case, comparisonof global and Finnish scenarios according to per capitaemissions is difficult because of a lack of knowledge ofFinland’s population projections, but the chosen sce-narios are seen to be similar enough to use B1 as abackground scenario for TechnoC. Carbon dioxideemissions in the scenarios KIO1C, BAUC, and TechnoC

are presented in Figure 1. Corresponding scenarios forother Kyoto Protocol gases have also been presented(Monni 2002).

When calculating radiative forcing of CO2, CH4, orN2O caused by a single country or an activity, thescenario for background concentration (the atmo-spheric concentration caused by global emissions) mustalso be chosen. When calculating radiative forcing ofthe fluorinated gases, the background concentration

404 S. Monni and others

has no effect on forcing. The scenarios for backgroundconcentration used here are the marker scenarios ofSRES scenario families A2, B1, and B2. The familymarkers are designated here according to the name ofthe scenario family. The calculated global backgroundconcentrations of CO2 in scenarios A2, B1, and B2 arepresented in Figure 2. The preindustrial concentrationof carbon dioxide is assumed to be 278 ppmv (IPCC2001). The concentration doubles by the year 2100 inthe B1 scenario, where it stabilizes at a level of about560 ppmv.

Radiative forcing of all Kyoto Protocol gases in theKIO1C scenario calculated with the averaged forcingapproach and using B2 as background scenario is pre-sented in Figure 3. In 1990, radiative forcing caused byFinland is 3.2 mW/m2. In the KIO1C scenario radiativeforcing doubles by the year 2100, when it is 7.8 mW/m2. Considerable use of fossil fuels started in Finlandaround 1950 and, therefore, the radiative forcing frommethane emissions (mainly from cattle breeding and

waste) caused the highest contribution to the totalforcing until the 1960s. In 1990, the share of carbondioxide is 71% of radiative forcing, whereas it is 83% in2100. The share of N2O remains almost constant, butthe share of CH4 decreases considerably by 2100. Thereare two main reasons for the decrease of methaneforcing: there is considerable potential to reduce Fin-land’s methane emissions from landfills, especially be-fore 2020–2030, and because of methane’s short atmo-spheric lifetime, the reduction of emissions affectsradiative forcing rapidly. The relative share of fluori-nated gases increases most: in 1999 their share is 0.1%and in 2100 it is nearly 3%. The main reason for theincrease of forcing caused by fluorinated gases is theirlong atmospheric lifetimes: PFCs and SF6 have lifetimesof 2600–50,000 years (IPCC 2001), and therefore prac-tically all fluorinated gases emitted by Finland are stillpresent in the atmosphere in 2100.

In Figure 4 radiative forcing of all Kyoto Protocolgases due to Finland’s emissions is presented for thethree considered scenarios. The background scenariosare B1 for TechnoC, B2 for KIO1C, and A2 for BAUC.Forcing is calculated with the averaged forcing ap-proach. In the BAUC scenario, Finland’s forcing in2100 is 11 mW/m2, in the TechnoC scenario 6.3 mW/m2, and in the KIO1C scenario 7.8 mW/m2. Althoughthe emissions in the TechnoC scenario are stronglydecreasing, the radiative forcing is increasing due toslow removal of greenhouse gases from the atmo-sphere.

In Figure 5 the KIO1C scenario is calculated forcarbon dioxide using scenarios B1, B2, and A2 as back-ground scenarios (Figure 2). In scenarios with higheratmospheric concentrations, the radiative forcingcaused by Finland is lower due to the saturation of

Figure 1. CO2 emissions from fossil and peat fuel use inFinland in three scenarios. Solid line: emission history andscenarios of the original scenario studies used. Dashed lines:extension of the scenarios in this study.

Figure 2. Atmospheric concentrations of carbon dioxide inthe SRES scenarios A2, B1, and B2.

Figure 3. Radiative forcing of all Kyoto Protocol gases in theKIO1C scenario calculated using the averaged forcing ap-proach. The scenario for background concentration is B2.“New” denotes so-called new greenhouse gases, i.e., HFCs,PFCs, and SF6.

Radiative Forcing Due to Finnish Emissions 405

radiative forcing. In the B1 scenario, in which the at-mospheric carbon dioxide concentration stabilizes to avalue of 560 ppmv the radiative forcing caused by Fin-land in 2100 is almost 5% higher than in the B2 sce-nario, which is selected as the corresponding scenariofor the KIO1C scenario. When the A2 scenario is set asbackground scenario, the forcing caused by Finland is9% lower than with B2 as background scenario. Thescenarios BAUC and TechnoC are also calculated withB2 as background scenario. In the BAUC scenario theforcing was 11% higher when the B2 scenario was usedas background scenario instead of the A2 scenario. Inthe model, the relative uptake capacity of CO2 of theoceans decreases with increasing atmospheric concen-tration. For this reason, additional carbon dioxide con-centration caused by Finland as a function of timeincreases with increasing background concentrationbecause carbon dioxide is removed from the atmo-sphere at a slower rate. This effect is opposite to theeffect of background concentration on radiative forc-

ing. However, as a net effect, the radiative forcingcaused by a single country or activity decreases withincreasing atmospheric background concentration.

In Figure 6, forcing caused by Finland in the KIO1C

scenario is presented using both the marginal forcingapproach and the averaged forcing approach. Corre-sponding calculations were also made for other scenar-ios, and the corresponding SRES scenarios are used asbackground scenarios. Already in 1990 the differencebetween the two approaches is 9%, and in 2050 it is23%–26% and in 2100 28%–40% depending on thescenario. The difference is highest in the BAUC sce-nario. Thus the consequent forcing is strongly depen-dent on the model used.

Choice of a forcing model affects the forcing ofmethane and nitrous oxide, although the effect is notas strong as in the case of carbon dioxide. When mar-ginal and averaged forcing of carbon dioxide, methane,and nitrous oxide together are calculated in the KIO1C

scenario, the difference between different approachesis 7% in 1950, 10% in 1990, about 20% in 2050, andabout 30% in 2100.

In Figure 7 Finland is compared with other coun-tries. Because of rather poor correspondence betweenFinnish and global scenarios, only one scenario is pre-sented to describe different methods to calculate Fin-land’s share of global emissions and radiative forcing.In 1990 Finland’s share of global emissions of all theKyoto Protocol gases was estimated to be 0.22%. Globalmethane emissions were taken from Stern and Kauf-mann (1998), fossil fuel carbon dioxide emissions fromMarland and others (2001), and nitrous oxide emis-sions from Kroeze and others (1999). Global emissionsof fluorinated gases were taken from Oliver and Bakker(2000) and Finland’s emissions of all Kyoto Protocolgases were taken from Aaltonen and others (2001).

Figure 4. Radiative forcing of all Kyoto Protocol gases calcu-lated using the averaged forcing approach in three scenarios.

Figure 5. Radiative forcing due to CO2 emissions in theKIO1C scenario using scenarios A2, B1, and B2 as scenariosfor background concentration (calculated with the averagedforcing approach).

Figure 6. Radiative forcing of CO2 calculated in the KIO1C

scenario using the averaged forcing approach and the mar-ginal forcing approach.

406 S. Monni and others

Finland’s share of global integrated emissions since1990 is only 0.19% in 1990, which indicates the shortemission history of Finland. If the integration hadstarted earlier, Finland’s share of integrated emissionswould have been even lower. In the year 2100 in theKIO1C scenario, Finland’s share of global emissions is0.10%, but the share of integrated emissions is 0.14%.Emissions due to developing countries are increasing,causing decrease in Finland’s share of annual emis-sions. However, the emission history of developingcountries is short, and therefore Finland’s share ofintegrated emissions is higher compared with annualemissions. The share of radiative forcing in 1990 is0.18% when it is calculated with the averaged forcingapproach in the scenario KIO1C. In the same year(1990) Finland’s share of the world population is 0.1%and the share of global GDP is 0.6% (EIA 2001). HenceFinland’s share of radiative forcing is double the shareof population. Because of Finland’s relatively shortemission history the share of emissions is higher thanthe share of radiative forcing. Finland’s share of theglobal population is also probably decreasing. In 2100Finland’s share of global radiative forcing is 0.13%, andthe share of integrated radiative forcing is 0.15% whencomparing scenarios KIO1C and B2. The integratedradiative forcing can be seen to describe the impact ofanthropogenic greenhouse gas emissions on globaltemperature increase. When Finland’s emissions arecompared with those of other Annex I countries, theshare of emissions of all Kyoto gases in the year 1990 is0.37%, but the share decreases to 0.33% by 2100 whencomparing the scenarios KIO1C and B2. Finland’s shareof radiative forcing due to Annex I countries is 0.27%in 1990 without fluorinated gases and it increases to0.32% by 2100.

Discussion and Conclusions

The purpose of this study was to calculate radiativeforcing due to Finnish greenhouse gas emissions ac-

cording to three emissions scenarios and using thelatest IPCC (2001) information in calculating radiativeforcing from atmospheric concentration. Another ob-jective was to study the effects of different forcing mod-els as well as different background scenarios on radia-tive forcing caused by a single country or activity. Sinksof carbon dioxide were not taken into account in thecalculations of this study. Sinks as calculated in accor-dance with the application rules of the Kyoto Protocolare rather small for Finland, although the actual sinksare much greater. The actual CO2 sink in Finland’sforests was 23.8 Mt CO2 in the reference year 1990. In1991 it was 38.2 Mt CO2, and since then it has mainlybeen decreasing. In 1999 the sink was 10.8 Mt CO2. In1990 the CO2 sink corresponded to 31% of total green-house gas emission, whereas in 1999 it corresponded to14% (Sarkkinen and others 2001). This sink is basedmainly on the age structure changes of forest stands.However, the Kyoto Protocol rules under paragraph 3.3take into account only changes of the forested area,which is slightly decreasing in Finland due to construc-tion of roads, houses, etc. According to the Kyoto Pro-tocol paragraphs 3.3 and 3.4 together, Finland’s calcu-lated carbon sink may be 0.6 Mt CO2 per year, which isless than 1% of the emissions in the 1990s (UNFCCC2001).

When calculating forcing caused by a country or anactivity, particular attention should be paid to thechoice of background scenario. In the case of Finland,the greatest difference between the forcing calculatedwith different background scenarios was 11%. Thebackground scenario used should be that which seemsmost probable when comparing the global scenariowith the scenario of a country or an activity.

The SRES scenarios of the A1 family were not in-cluded in this study. If the marker scenario of the A1family, the A1B scenario, had been used instead of theB2 scenario, the consequent forcing of carbon dioxidecaused by Finland would have been lower. In the A1B

Figure 7. Finland’s share of global emis-sions, integrated emissions, radiativeforcing, and integrated radiative forcingin 1990 and 2100. The first year of inte-gration is 1900. All Kyoto Protocol gasesare considered and weighted with 100-year GWPs in the case of the two firstcolumn sets. The scenario for Finland isKIO1C and the global scenario is B2.Dashed lines in the radiative forcing col-umns show forcing calculated with themarginal forcing approach.

Radiative Forcing Due to Finnish Emissions 407

scenario, global emissions are higher than in the B2scenario almost until the year 2100, although theshapes of the scenarios are different. In the B2 scenarioglobal emissions are increasing at a relatively slow rate,whereas in the A1B scenario emissions increase morerapidly at the beginning of the century and begin todecrease about the year 2050. The atmospheric carbondioxide concentration is maximally about 16% higherin the A1B scenario than in the B2 scenario (IPCC2001), leading to a lower forcing due to Finnish emis-sions.

The difference between different forcing ap-proaches (marginal forcing approach and averagedforcing approach) was at its highest 40% in the casestudied. The effect of the marginal forcing approach issimilar to that discussed by den Elzen and Schaeffer(2000), but the results cannot be compared directlybecause of the different calculation methods used.When calculating with the marginal forcing approachof this study, the ensuing forcings are usually low. Theuse of the averaged forcing approach is recommended,because then the forcings of different countries can besummed up, and the sum of the forcings of all coun-tries is equal to global forcing. The marginal forcingapproach can be used when studying forcing of someglobally “additional” event.

The absolute uncertainties in calculating atmo-spheric concentrations of greenhouse gases and radia-tive forcing due to concentration increase are high.The sources of uncertainty are emission estimates, cal-culation of concentration, and calculation of radiativeforcing. According to Aaltonen and others (2001), thetotal uncertainty in Finnish greenhouse gas emissionestimates was 7% in 1999, mainly due to high uncer-tainty in emissions from land use change and in non-CO2 greenhouse gases. The uncertainties are definedas the ratio of half of the 95% confidence interval andthe mean value expressed as percentages. The uncer-tainties in fossil fuel carbon dioxide emissions are low.For example, in energy industries, the uncertainty inCO2 emissions from fuel combustion is 3% for liquidfuels, 4% for solid fuels and 1% for gaseous fuels.Hence, according to Sinisalo (1998), the major sourceof uncertainty for fossil fuel CO2 is the calculation ofconcentration and radiative forcing. Sinisalo (1998)simulated the uncertainty in concentration calculationssimilar to the method used in this study by modifyingpulse–response coefficients and arrived at an uncer-tainty of 20% for both concentration and radiativeforcing (Sinisalo 1998). However, total uncertainty canbe greater. Methane and nitrous oxide emissions havemuch higher uncertainty than CO2 emissions, beingthe greatest source of uncertainty in radiative forcing

calculations for these gases (Sinisalo 1998). Even in theenergy industry, methane emissions have an uncer-tainty of 30% and nitrous oxide emissions an uncer-tainty of 50%. Methane and nitrous oxide emissionsfrom agriculture and waste have even higher uncertain-ties (Aaltonen and others 2001). According to IPCC(2001), the uncertainty range of current (2000) glo-bally averaged direct radiative forcing is less than 10%for carbon dioxide, 15% for methane, 10% fornitrous oxide, and 10%–15% for halogenated hydro-carbons. The uncertainty in indirect radiative forcingdue to methane is far higher, but its contribution to thetotal forcing is rather small. However, the relative un-certainty, e.g., between two scenarios is relatively low,because the error sources correlate, thus decreasing theuncertainty (Sinisalo 1998). This can also be seen to bevalid for two countries or activities, if the structures ofemissions are similar.

According to this study the radiative forcing (calcu-lated with the averaged forcing approach) due to Finn-ish emissions in 1990 is about 3.2 mW/m2. About 2.3mW/m2 is due to CO2 emissions, 0.5 mW/m2 to CH4

emissions, and 0.4 mW/m2 to N2O emissions. Theshare of fluorinated gases is very low, 0.0001 mW/m2 in1990. The use of fossil fuel before the 1950s in Finlandwas very low and the radiative forcing due to methanewas the greatest contributor until the 1960s. The radi-ative forcing in the three emission scenarios consideredvaries between 6 and 11 mW/m2 in 2100. Thus in theyear 2100 the radiative forcing will be much higherthan in 1990 even in the scenario of lowest and stronglydecreasing emissions. The share of methane of radia-tive forcing will decrease to 2%–3% by 2100. The shareof fluorinated gases is increasing, being higher than theshare of methane in 2100 in the scenarios KIO1C andTechnoC. Finland’s share of global emissions was 0.22%in 1990, but will decrease to 0.10% by 2100 mainlybecause of the increasing emissions of developed coun-tries when KIO1C and B2 are considered. Finland’sshare of radiative forcing was 0.18% in 1990. The lowershare of forcing compared to emissions indicates Fin-land’s short emission history. Finland’s share of forcingwill be 0.13% in 2100. The changes in forcing are farslower than the changes in emissions because of theinertial features of climate change.

Reduction of radiative forcing is rather difficult be-cause of the inertial features of climate change. Even instrongly decreasing emissions scenarios, the radiativeforcing might continue to increase. This is one of thereasons why mitigation of climate change is considereddifficult. In the case of Finland, methane was the onlygreenhouse gas with decreasing radiative forcing, evenin the TechnoC scenario. Reducing methane emissions

408 S. Monni and others

is the easiest way to reduce global forcing in the shortrun because of its relatively short atmospheric lifetime,but it has a limited potential. In the long run, reductionof carbon dioxide emissions is most important.

Literature Cited

Aaltonen, J., T. Palosuo, and R. Pipatti. 2001. Key sourceidentification in the Finnish 1999 greenhouse gas inven-tory. VTT energy reports 34/2001. Espoo, Finland, 28 pp.

den Elzen, M., and M. Schaeffer. 2000. Assessment of majoruncertainties in calculating regional contributions to cli-mate change. RIVM report no. 728001012. National Insti-tute of Public Health and the Environment, Bilthoven, TheNetherlands, 47 pp.

EIA (Energy Information Administration). 2001. Interna-tional Energy Annual 1999. DOE/EIA-0219(99). Office ofEnergy Markets and End Use US Department of Energy,Washington, DC, 251 pp.

Enting, I. 1998. Attribution of Greenhouse gas emissions,concentrations and radiative forcing. CSIRO atmosphericresearch technical paper no. 38. Australia, 27 pp.

Enting, I., T. Wigley, and M. Heimann. 1994. Future emissionsand concentrations of carbon dioxide. Key Ocen/Atmo-sphere/Land analyses. Tecnical report 31. CSIRO Divisionof Atmospheric Research, Melbourne, Australia, 127 pp.

Filho, M., and J. Miguez. 2000. Note on the time-dependentrelationship between emissions of greenhouse gases andclimate change. Technical note. Ministry of Science andTechnology, Brazil, 40 pp.

IPCC (Intergovernmental Panel on Climate Change). 1995.Climate change 1994: radiative forcing of climate changeand an evaluation of the IPCC IS92 emission scenarios.Cambridge University Press, Cambridge, UK, 339 pp.

IPCC (Intergovernmental Panel on Climate Change). 1997.An introduction to simple climate models used in the IPCCsecond assessment report. IPCC Geneva, Switzerland, 51pp.

IPCC (Intergovernmental Panel on Climate Change). 1999.Aviation and the global atmosphere. Cambridge UniversityPress, Cambridge, UK, 373 pp.

IPCC (Intergovernmental Panel on Climate Change). 2000.Special report on emissions scenarios. Cambridge Univer-sity Press, Cambridge, UK, 595 pp.

IPCC (Intergovernmental Panel on Climate Change). 2001.Climate change 2001: The scientific basis. Contribution ofworking group 1 to the third assessment report of theintergovernmental Panel on Climate Change. CambridgeUniversity Press, Cambridge, UK, 881 pp.

Joos, F., M. Bruno, R. Fink, U. Siegenthaler, and T. Stocker.1996. An efficient and accurate representation of complexoceanic and biospheric models of anthropogenic carbonuptake. 48B. Tellus 397–417.

Kara, M., R. Hirvonen, L. Mattila, S. Viinikainen, S. Tuh-kanen, and I. Lind. 2001. Energy visions 2030 for Finland.Edita Plc, Helsinki, Finland, 237 pp.

Korhonen, R., I. Savolainen, and J. Sinisalo. 1993. Assessingthe impact of CO2 emission control scenarios in Finland onradiative forcing and greenhouse effect. Environmental Man-agement 17:797–805.

Korhonen, R., K. Pingoud, I. Savolainen, and R. Matthews.2001. The role of carbon sequestration and the tonne-yearapproach in fulfilling the objective of climate convention(submitted).

Kroeze, C., A. Mosier, and L. Bouwman. 1999. Closing theglobal N2O budget: A retrospective analysis 1500–1994.Global Biochemical Cycles 13:1–8.

Lehtila, A., and S. Tuhkanen. 1999. Integrated cost-effective-ness analysis of greenhouse gas emission abatement. VTTpublications 374. Libella Painopalvelu Oy, Espoo, Finland,145 pp.

Maier-Reimer, E., and K. Hasselmann. 1987. Transport andstorage of CO2 in the ocean—an inorganic ocean-circula-tion carbon cycle model. Climate Dynamics 2:63–90.

Marland, G., T. A. Boden, and R. J. Anders. 2001. Global,regional, and national CO2 emissions. In Trends: a com-pendium of data on global change. Carbon Dioxide Infor-mation Analysis Center, Oak Ridge National Laboratory, USDepartment of Department of Energy, Oak Ridge, Tennes-see.

Monni, S. 2002. A calculation model concerning warmingeffect of greenhouse gas emissions and its application tointernational comparisons. Master’s thesis. Helsinki Univer-sity of Technology, Espoo, Finland (in Finnish).

Oliver, J., and J. Bakker. 2000. Historical global emissiontrends of the Kyoto Protocol gases HFCs, PFCs and SF6. SF6

and the environment: emission reduction strategies, 2.-3.11.2000. San Diego, California.

Sarkkinen, S., H. Granholm, L. Kolttola, M. Kosonen, J. Ojala,J. Petaja, A. Parnanen-Landtman, J. Roos, H. Sourama, R.Saari, E. Kuusisto, and K. Hamekoski. 2001. Finland’s thirdnational communication under the United Nations Frame-work Convention on Climate Change. Karisto Oy, Hameen-linna, Finland, 187 pp.

Savolainen, I., K. Hillebrand, I. Nousiainen, and J. Sinisalo.1994. Comparison of radiative forcing impacts of the use ofwood, peat and fossil fuels. World Resource Review 6:248–262.

Sinisalo, J. 1998. Estimation of greenhouse impacts of contin-uous regional emissions. Technical Research Centre of Fin-land, Espoo, Finland, 53 pp.

Stern, D. I., and R. K. Kaufmann. 1998. Annual estimates ofglobal anthropogenic methane emissions: 1860–1994. InTrends online: a compendium of data on global change.Carbon Dioxide Information Analysis Center, Oak RidgeNational Laboratory, US Department of Energy, Oak Ridge,Tennessee.

UNFCCC. 2001. Preparations for the first session of the con-ference of the parties serving as the meeting of the partiesto the Kyoto Protocol (decision 8/CP.4). Matters relating toland-use, land-use change and forestry. FCCC/CP/2001/L.11. Bonn.

UNFCCC Secretariat. 1997. Paper no. 1: Brazil; Proposedelements of a protocol to the United Nations FrameworkConventions on Climate Change. Presented by Brazil in

Radiative Forcing Due to Finnish Emissions 409

response to the Berlin Mandate. UNFCCC/AGBM/1997/MISC.1/Add.3 GE.-97-. Bonn.

Uppenberg, S., L. Zetterberg, and M. Åhman. 2001. Climateimpact from peat utilisation in Sweden. IVL Report B 1423.Stockholm, Sweden, 39 pp.

Wuebbles, D., and J. Edmonds. 1991. Primer on greenhousegases. Lewis Publishers, Inc., Chelsea, Michigan, 230 pp.

Appendix 1: Equations to Calculate AdditionalConcentration in Atmosphere and RadiativeForcing

Transfer of carbon dioxide from the atmosphere tooceans is modeled with a pulse–response function(A1), which is a superposition of four exponentials withdifferent relaxation times (Maier-Reimer and Hassel-mann 1987):

fCO2�t� � a0 � a1e � t/�1 � a2e � t/�2 � a3e � t/�3 � a4e � t/�4

(A1)

Parameters of the pulse–response function are definedfor a step-function increase of preindustrial CO2 con-centration in the atmosphere by a factor of 1.25, 2, and4 and are presented in Table A1. The parameters arefitted to the computed response of a three-dimensionalocean carbon model (Maier-Reimer and Hasselmann1987). Fraction a0 of an emission pulse remains in theatmosphere. In the REFUGE2 model, pulse–responsefunctions for different step-function increases (1.25, 2,and 4) are weighted according to global atmosphericconcentration.

Removal of methane, nitrous oxide, and the fluori-nated gases is given by a pulse–response function (A2)with one exponential only (IPCC 1997):

f�t� � e �t� (A2)

where � is the average atmospheric lifetime of the gas.In the case of methane and nitrous oxide, the atmo-spheric lifetime depends on the concentration of thegas in the atmosphere according to Table A2.

Concentration in the atmosphere due to emissions iscalculated as an integral A3 (Maier-Reimer and Hassel-mann 1987):

C�t� � �t0

t

S�u� f�t � u�du � C0 (A3)

where S(u) is the emission source.According to IPCC (2001), globally averaged radia-

tive forcing due to CO2 concentration increase can becalculated using equation (A4):

�FCO2 � 5.35ln� CC0� (A4)

where C denotes carbon dioxide concentration and thesubscript 0 the undisturbed concentration.

Direct forcing due to methane is defined as (IPCC2001)

�FCH4 � 0.036��M � �M0� � �f�M, N0� � f�M0, N0��

(A5)

where M is atmospheric concentration of methane andN is atmospheric concentration of nitrous oxide.

For nitrous oxide the globally averaged radiativeforcing is (IPCC 2001)

Table A1. Parameters of pulse–response functionused in REFUGE2 modela

Step function 1.25 2 4

a0 0.131 0.142 0.166a1 0.201 0.241 0.356a2 0.321 0.323 0.285a3 0.249 0.206 0.130a4 0.098 0.088 0.063�1 (yrs) 362.9 313.8 326.3�2 (yrs) 73.6 79.8 91.3�3 (yrs) 17.3 18.8 18.9�4 (yrs) 1.9 1.7 1.2aParameters are defined for step-function increases for the initial CO2

concentration in the atmosphere by factors of 1.25, 2, and 4 (Maier-Reimer and Hasselmann 1987).

Table A2. Lifetimes of methane and nitrous oxideaccording to a specific atmospheric concentration

CH4concentration(ppbv)

CH4lifetime(year)

N2Oconcentration

(ppbv)

N2Olifetime(year)

732 6.7 270 120.9813 6.9 284 120.6903 7.1 293 120.4

1004 7.3 302 120.21115 7.5 314 1201239 7.7 324 119.81377 7.9 333 119.61530 8.2 346 119.41700 8.4 357 119.21870 8.6 368 1192057 8.9 383 188.82489 9.4 395 188.62738 9.6 411 118.43012 9.9 423 188.23313 10.2 436 1183644 10.5 454 117.84009 10.8

410 S. Monni and others

�FN2O � 0.12��N � �N0� � �f�M0, N� � f�M0, N0��

(A6)

Function f(M,N) takes into account the overlap of ni-trous oxide and methane (IPCC 2001)

f�M, N� � 0,47ln�1 � 2,01*10 � 5*�MN�0,75

� 5,31*10 � 15M�MN�1,52� (A7)

For the fluorinated greenhouse gases globally averagedradiative forcing is defined as (IPCC 2001)

�Fnew � �new�X � X0� (A8)

where X denotes the concentration of the gas in ques-tion and � is a gas-specific constant for radiative effi-ciency [W/m2/ppbv] as defined in (IPCC 2001, Table6, 7).

Radiative Forcing Due to Finnish Emissions 411