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K1170637 190211
UNITEDNATIONS
EP UNEP/GC.26/INF/20
Governing Councilof the United NationsEnvironment Programme
Distr.: General
17 February 2011
English only
Twenty-sixth session of the Governing Council/
Global Ministerial Environment ForumNairobi, 2124 February 2011
Item 4 (a) of the provisional agenda
Policy issues: state of the environment
Summary for decision makers of the integrated assessment of
black carbon and tropospheric ozone
Note by the Executive Director
Summary
The Executive Director has the honour to provide, in the annex to the present note, a
prepublication version of the summary for decision makers of the Integrated Assessment of Black
Carbon and Tropospheric Ozone, as referred to in the report by the Executive Director on the state ofthe environment and contribution of the United Nations Environment Programme to meeting
substantive environmental challenges (UNEP/GC.26/4). It has been reproduced without formal
editing.
UNEP/GC.26/1.
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Integrated Assessmentof Black Carbonand Tropospheric Ozone
Summary for Decision Makers
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A complete elaboration of the topics covered in this summary can be found in the Integrated Assessment of Black Carbon and
Tropospheric Ozone report and in the fully referenced underlying research, analyses and reports.
For details of UNEPs regional and sub-regional areas referred to throughout this document see
http://geodata.grid.unep.ch/extras/geosubregions.php.
Copyright: UNEP and WMO 2011 Integrated Assessment of Black Carbon and Tropospheric Ozone: Summary for DecisionMakers.
This is a pre-publication version of the Summary for Decision Makers. Please do not cite page numbers from thisversion or quote from it. These materials are produced for informational purposes only and may not be duplicated.
UNEP/GC/26/INF/20
Disclaimers
The views expressed in this document are not necessarily those of the agencies cooperating in this project. The designations
employed and the presentation do not imply the expression of any opinion whatsoever on the part of UNEP and WMOconcerning the legal status of any country, territory or city or its authority, or concerning the delimitation of its frontiers or
boundaries.
Mention of a commercial company or product in this document does not imply endorsement by UNEP and WMO. The use of
information from this document for publicity or advertising is not permitted. Trademark names and symbols are used in aneditorial fashion with no intention on infringement on trademark or copyright laws.
We regret any errors or omissions that may have been unwittingly made.
Maps, photos and illustrations as specified.
Writing team: Coordinators Drew Shindell (National Aeronautics and Space Administration, Goddard Institute for SpaceStudies, USA) and Johan C. I. Kuylenstierna (Stockholm Environment Institute, University of York, UK); Writers Kevin Hicks
(Stockholm Environment Institute, University of York, UK), Frank Raes (Joint Research Centre, European Commission, Italy),
Veerabhadran Ramanathan (Scripps Institution of Oceanography, USA), Erika Rosenthal (Earth Justice, USA), Sara Terry (US
Environmental Protection Agency), Martin Williams (Kings College London, UK).
With inputs from: Markus Amann (International Institute for Applied Systems Analysis, Austria), Susan Anenberg (US
Environmental Protection Agency), Volodymyr Demkine (UNEP, Kenya), Lisa Emberson (Stockholm Environment Institute,
University of York, UK), David Fowler (The Centre for Ecology and Hydrology, UK), Liisa Jalkanen (WMO, Switzerland), Zbigniew
Klimont (International Institute for Applied Systems Analysis, Austria), N. T. Kim Oahn, (Asian Institute of Technology, Thailand),Joel Schwartz (Harvard University, USA), David Streets (Argonne National Laboratory, USA), Rita van Dingenen (Joint Research
Centre, European Commission, Italy), Harry Vallack (Stockholm Environment Institute, University of York, UK), Elisabetta Vignati(Joint Research Centre, European Commission, Italy).
With advice from the High-level Consultative Group especially: Ivar Baste (UNEP, Switzerland), Adrin Fernndez Bremauntz
(National Institute of Ecology, Mexico), Harald Dovland (Ministry of Environment, Norway), Dale Evarts (US EnvironmentalProtection Agency), Rob Maas (The National Institute for Public Health and the Environment, Netherlands), Pam Pearson
(International Cryosphere Climate Initiative, Sweden/USA), Sophie Punte (Clean Air Initiative for Asian Cities, Philippines),
Andreas Schild (International Centre for Integrated Mountain Development, Nepal), Surya Sethi (Former Principal Adviser
Energy and Core Climate Negotiator, Government of India), George Varughese (Development Alternatives Group, India), RobertWatson (Department for Environment, Food and Rural Affairs, UK).
Editor: Bart Ullstein (Banson, UK).
Design and layout: Audrey Ringler (UNEP, Kenya).
Printing: UNON/Publishing Services Section/Nairobi, ISO 14001:2004-certified.
Cover photographs: credits
1. Kevin Hicks
2. Caramel/ickr
3. Veerabhadran Ramanathan
4. Christian Lagerek/Shutterstock Images5. John Ogren, NOAA
6. Raphal V/ickr
7. Robert Marquez
8. Jerome Whittingham/Shutterstock Images9. Brian Tan/Shutterstock Images
UNEP promotes
environmentally sound practicesglobally and in its own activities. This
publication is printed on 100% recycled paper
using vegetable based inks and other eco-
friendly practices. Our distribution policy aims to
reduce UNEPs carbon footprint.
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4 5
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Table of Contents
Main Messages 1The challenge 1
Reducing emissions 2
Benetsof emissionreductions 3
Responses 3
Introduction 5
Limiting Near-Term Climate Changes and Improving Air Quality 8
Identifyingeffectiveresponsemeasures 8
Achievinglargeemissionreductions 8
Reducingnear-termglobalwarming 10
Stayingwithincriticaltemperaturethresholds 12
Benetsofearlyimplementation 13
Regionalclimatebenets 13
TropicalrainfallpatternsandtheAsianmonsoon 13
Decreasedwarminginpolarandotherglaciatedregions 15
Benetsof themeasuresforhumanhealth 16
Benetsofthemeasuresforcropyields 16
Relativeimportanceandscienticcondenceinthemeasures 18
Mechanismsforrapidimplementation 19
Potentialinternationalregulatoryresponses 22
Opportunitiesforinternationalnancingandcooperation 23
Concluding Remarks 24
Glossary 25
Acronyms and Abbreviations 27
Acknowledgements 28
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1
Summary or Decision Makers
Main Messages
Scientic evidence and new analyses demonstrate that control of black carbon
particles and tropospheric ozone through rapid implementation of proven
emission reduction measures would have immediate and multiple benets for
human well-being
Blackcarbonexistsasparticlesintheatmosphereandisamajorcomponentofsoot,ithas
signicanthumanhealthandclimateimpacts.Atgroundlevel,ozoneisanairpollutantharmful
tohumanhealthandecosystems,andthroughoutthetroposphere,orloweratmosphere,isalso
asignicantgreenhousegas.Ozoneisnotdirectlyemitted,butisproducedfromemissionsof
precursorsofwhichmethaneandcarbonmonoxideareofparticularinteresthere.
THE CHALLENGE1 The climate is changing now, warming at the highest rate in polar and high-
altitude regions Climatechange,eveninthenearterm,hasthepotentialtotrigger
abrupttransitionssuchasthereleaseofcarbonfromthawingpermafrostandbiodiversity
loss.Theworldhaswarmedbyabout0.8Cfrompre-industriallevels,asreportedbythe
Traditional brick kilns in South Asia are a major source o black carbon. Improved kiln design in this region issignicantly reducing emissions.
Credit:KevinHicks
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Integrated Assessment o Black Carbon and Tropospheric Ozone
IntergovernmentalPanelonClimateChange(IPCC).ThePartiestotheUnitedNations
FrameworkConventiononClimateChange(UNFCCC)haveagreedthatwarmingshould
notexceed2Cabovepre-industriallevels.
2 Black carbon and ozone in the lower atmosphere are harmful air pollutants
that have substantial regional and global climate impacts Theydisturb
tropicalrainfallandregionalcirculationpatternssuchastheAsianmonsoon,affectingthe
livelihoods of millions of people
3 Black carbons darkening of snow and ice surfaces increases their absorption
of sunlight, which, along with atmospheric heating, exacerbates melting of
snow and ice around the world, including in the Arctic, the Himalayas and
other glaciated and snow-covered regions Thisaffectsthewatercycleandincreases
risksofooding.
4 Black carbon, a component of particulate matter, and ozone both lead to
adverse impacts on human health leading to premature deaths worldwideOzone is also the most important air pollutant responsible for reducing crop
yields, and thus affects food security.
REDUCINGEMISSIONS
5 Reducing black carbon and tropospheric ozone now will slow the rate of
climate change within the rst half of this century. Climate benets from
reduced ozone are achieved by reducing emissions of some of its precursors,
especially methane which is also a powerful greenhouse gas.Theseshort-lived
climateforcersmethane,blackcarbonandozonearefundamentallydifferentfromlonger-livedgreenhousegases,remainingintheatmosphereforonlyarelativelyshorttime.
Deepandimmediatecarbondioxidereductionsarerequiredtoprotectlong-termclimate,
asthiscannotbeachievedbyaddressingshort-livedclimateforcers.
6 A small number of emission reduction measures targeting black carbon and
ozone precursors could immediately begin to protect climate, public health,
water and food security, and ecosystems.Measuresincludetherecoveryofmethane
fromcoal,oilandgasextractionandtransport,methanecaptureinwastemanagement,use
ofclean-burningstovesforresidentialcooking,dieselparticulateltersforvehiclesandthe
banningofeldburningofagriculturalwaste.Widespreadimplementationisachievable
withexistingtechnologybutwouldrequiresignicantstrategicinvestmentandinstitutionalarrangements.
7 The identied measures complement but do not replace anticipated carbon
dioxide reduction measures. Majorcarbondioxidereductionstrategiesmainly
targettheenergyandlargeindustrialsectorsandthereforewouldnotnecessarilyresultin
signicantreductionsinemissionsofblackcarbonortheozoneprecursorsmethaneand
carbonmonoxide.Signicantreductionoftheshort-livedclimateforcersrequiresaspecic
strategy,asmanyareemittedfromalargenumberofsmallsources.
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Summary or Decision Makers
BENEFITSOFEMISSIONREDUCTIONS
8 Full implementation of the identied measures would reduce future global
warming by 0.5C (within a range of 0.20.7C, Figure 1). Ifthemeasureswere
tobeimplementedby2030,theycouldhalvethepotentialincreaseinglobaltemperatureprojectedfor2050comparedtotheAssessmentsreferencescenariobasedoncurrent
policiesandenergyandfuelprojections.Therateofregionaltemperatureincreasewould
alsobereduced.
9 Both near-term and long-term strategies are essential to protect climate
Reductionsinnear-termwarmingcanbeachievedbycontroloftheshort-livedclimate
forcerswhereascarbondioxideemissionreductions,beginningnow,arerequiredtolimit
long-termclimatechange.Implementingbothreductionstrategiesisneededtoimprovethe
chancesofkeepingtheEarthsglobalmeantemperatureincreasetowithintheUNFCCC
2Ctarget.
10 Full implementation of the identied measures would have substantial
benets in the Arctic, the Himalayas and other glaciated and snow-covered
regions ThiscouldreducewarmingintheArcticinthenext30yearsbyabouttwo-thirds
comparedtotheprojectionsoftheAssessmentsreferencescenario.Thissubstantially
decreasestheriskofchangesinweatherpatternsandamplicationofglobalwarming
resultingfromchangesintheArctic.Regionalbenetsoftheblackcarbonmeasures,such
astheireffectsonsnow-andice-coveredregionsorregionalrainfallpatterns,arelargely
independentoftheirimpactonglobalmeanwarming.
11 Full implementation of the identied measures could avoid 2.4 million
premature deaths (within a range of 0.74.6 million) and the loss of 52 million
tonnes (within a range of 30140 million tonnes), 14 per cent, of the globalproduction of maize, rice, soybean and wheat each year (Figure 1).The most
substantialbenetswillbefeltimmediatelyinorclosetotheregionswhereactionistaken
toreduceemissions,withthegreatesthealthandcropbenetsexpectedinAsia.
RESPONSES
12. Theidentiedmeasuresareallcurrentlyinuseindifferentregionsaroundtheworldto
achieveavarietyofenvironmentanddevelopmentobjectives.Much wider and more
rapid implementation is required to achieve the full benets identied in this
Assessment
13 Achieving widespread implementation of the identied measures would be
most effective if it were country- and region-specic, and could be supported
by the considerable existing body of knowledge and experience. Accounting
fornear-termclimateco-benetscouldleverageadditionalactionandfundingonawider
internationalscalewhichwouldfacilitatemorerapidimplementationofthemeasures.
Manymeasuresachievecostsavingsovertime.However,initialcapitalinvestmentcouldbe
problematicinsomecountries,necessitatingadditionalsupportandinvestment.
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Integrated Assessment o Black Carbon and Tropospheric Ozone
14 At national and sub-national scales many of the identied measures could
be implemented under existing policies designed to address air quality and
development concerns Improved cooperation within and between regions
would enhance widespread implementation and address transboundary
climate and air quality issues Internationalpolicyandnancinginstruments
toaddresstheco-benetsofreducingemissionsofshort-livedclimateforcersneed
developmentandstrengthening.Supportingandextendingexistingrelevantregional
arrangementsmayprovideanopportunityformoreeffectivecooperation,implementationandassessmentaswellasadditionalmonitoringandresearch.
15 The Assessment concludes that there is condence that immediate and
multiple benets will be realized upon implementation of the identied
measuresThedegreeofcondencevariesaccordingtopollutant,impactandregion.
Forexample,thereishighercondenceintheeffectofmethanemeasuresonglobal
temperaturesthanintheeffectofblackcarbonmeasures,especiallywheretheserelate
totheburningofbiomass.Thereisalsohighcondencethatbenetswillberealizedfor
humanhealthfromreducingparticles,includingblackcarbon,andtocropyieldsfrom
reducingtroposphericozoneconcentrations.Giventhescienticcomplexityoftheissues,
furtherresearchisrequiredtooptimizenear-termstrategiesindifferentregionsandtoevaluatethecost-benetratioforindividualmeasures.
Figure 1. Global benets rom ull implementation o the identied measures in 2030 compared to the reerencescenario. The climate change benet is estimated or a given year (2050) and human health and crop benets are
or 2030 and beyond.
0
CH4measures
CH4 + BC
measures
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Climate change
Global mean
avoided
warming in 2050
(C)
0
CH4measures
CH4 + BC
measures
1
0.5
1.5
2
2.5
3
3.5
4
4.5
5
Human health
Annually avoided
premature
deaths
(million)
0
CH4measures
CH4 + BC
measures
25
50
75
100
125
150
Food security
Annually avoided
crop yield losses
(total maize,
rice, soybean
and wheat,
million tonnes)
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Summary or Decision Makers
Introduction
Blackcarbon(BC,Box1)andtropospheric
ozone(O3,Box2)areharmfulairpollutants
thatalsocontributetoclimatechange.In
recentyears,scienticunderstandingofhow
BC and O3
affect climate and public health
hassignicantlyimproved.Thishascatalysed
ademandforinformationandaction
fromgovernments,civilsocietyandother
stakeholders.TheUnitedNations(UN)has
beenrequestedtourgentlyprovidescience-
basedadviceonactiontoreducetheimpacts
of these pollutants1
TheUnitedNationsEnvironment
Programme(UNEP),inconsultationwith
partners,initiatedanassessmentdesigned
toprovideaninterfacebetweenknowledge
andaction,scienceandpolicy,andto
provideascienticallycrediblebasisfor
informeddecision-making.Theresultis
acomprehensiveanalysisofdriversof
emissions,trendsinconcentrations,and
impactsonclimate,humanhealthand
ecosystemsofBC,troposphericO3 and itsprecursors.BC,troposphericO
3and
methane(CH4)areoftenreferredtoas
short-livedclimateforcers(SLCFs)asthey
haveashortlifetimeintheatmosphere
(daystoaboutadecade)relativetocarbon
dioxide(CO2).
TheAssessmentisanintegratedanalysisof
multipleco-emittedpollutantsreectingthe
factthatthesepollutantsarenotemittedin
isolation(Boxes1and2).TheAssessmentdeterminedthatundercurrentpolicies,
emissions of BC and O3precursorsare
expectedgloballyeithertoincreaseorto
remainroughlyconstantunlessfurther
mitigation action is taken
The Integrated Assessment of Black Carbon and
Tropospheric Ozone convenedmorethan50______________________________________________1 The Anchorage Declaration o 24 April 2009, adopted by the I ndigenous Peoples Global Summit on Climate Change; the Troms Declaration o 29 April
2009, adopted by the Sixth Ministerial Meeting o the Arctic Council and the 8th Session o the Permanent Forum on Indigenous Issues under the United
Nations Economic and Social Council (May 2009) called on UNEP to conduct a ast track assessment o short-term drivers o climate change, specically
BC, with a view to initiating the negotiation o an international agreement to reduce emissions o BC. A need to take rapid action to address signicantclimate orcing agents other than CO2, such as BC, was reected in the 2009 declaration o the G8 leaders (Responsible Leadership or a Sustainable
Future, LAquila, Italy, 2009).
authorstoassessthestateofscienceand
existingpolicyoptionsforaddressingthese
pollutants.TheAssessmentteamexamined
policyresponses,developedanoutlookto2070
illustratingthebenetsofpoliticaldecisions
madetodayandtheriskstoclimate,human
healthandcropyieldsoverthenextdecadesif
actionisdelayed.Placingapremiumonrobust
scienceandanalysis,theAssessmentwasdriven
byfourmainpolicy-relevantquestions:
Whichmeasuresarelikelytoprovide
signicantcombinedclimateandair-qualitybenets?
Howmuchcanimplementationofthe
identiedmeasuresreducetherateof
globalmeantemperatureincreasebymid-
century?
Whatarethemultipleclimate,healthand
crop-yieldbenetsthatwouldbeachieved
byimplementingthemeasures?
Bywhatmechanismscouldthemeasures
berapidlyimplemented?
Inordertoanswerthesequestions,the
Assessmentteamdeterminedthatnewanalyses
wereneeded.TheAssessmentthereforerelies
onpublishedliteratureasmuchaspossible
andonnewsimulationsbytwoindependent
climate-chemistry-aerosolmodels:one
developedandrunbytheNASA-Goddard
InstituteforSpaceStudies(GISS)andthe
otherdevelopedbytheMaxPlanckInstitute
inHamburg,Germany(ECHAM),andrun
attheJointResearchCentreoftheEuropeanCommissioninIspra,Italy.Thespecic
measuresandemissionestimatesforusein
developingthisAssessmentwereselectedusing
theInternationalInstituteforAppliedSystems
AnalysisGreenhouseGasandAirPollution
InteractionsandSynergies(IIASAGAINS)
model.Foramoredetaileddescriptionofthe
modellingseeChapter1.
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Integrated Assessment o Black Carbon and Tropospheric Ozone
Box1:Whatisblackcarbon?Black carbon (BC) exists as particles in the atmosphere and is a major component o soot. BC is not
a greenhouse gas. Instead it warms the atmosphere by intercepting sunlight and absorbing it. BC
and other particles are emitted rom many common sources, such as cars and trucks, residentialstoves, orest res and some industrial acilities. BC particles have a strong warming eect in the
atmosphere, darken snow when it is deposited, and inuence cloud ormation. Other particles may
have a cooling eect in the atmosphere and all particles inuence clouds. In addition to having an
impact on climate, anthropogenic particles are also known to have a negative impact
on human health.
Black carbon results rom the incomplete combustion o ossil uels, wood and other biomass.
Complete combustion would turn all carbon in the uel into carbon dioxide (CO2). In practice,
combustion is never complete and CO2, carbon monoxide (CO), volatile organic compounds
(VOCs), organic carbon (OC) particles and BC particles are all ormed. There is a close relationship
between emissions o BC (a warming agent) and OC (a cooling agent). They are always co-emitted,
but in dierent proportions or dierent sources. Similarly, mitigation measures will have varying
eects on the BC/OC mix.
The black in BC reers to the act that these particles absorb visible light. This absorption leads to
a disturbance o the planetary radiation balance and eventually to warming. The contribution to
warming o 1 gramme o BC seen over a period o 100 years has been estimated to be anything
rom 100 to 2 000 times higher than that o 1 gramme o CO2. An important aspect o BC particles
is that their lietime in the atmosphere is short, days to weeks, and so emission reductions have an
immediate benet or climate and health.
High emitting vehicles are a signicant source o blackcarbon and other pollutants in many countries.
Haze with high particulate matter concentrations
containing BC and OC, such as this over the Bay o
Bengal, is widespread in many regions.
Credit:Carame
l/fickr
Credit:NASA-MODIS
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Summary or Decision Makers
Box2:Whatistroposphericozone?Ozone (O
3) is a reactive gas that exists in two layers o the atmosphere: the stratosphere (the upper
layer) and the troposphere (ground level to ~1015 km). In the stratosphere, O3
is considered
to be benecial as it protects lie on Earth rom the suns harmul ultraviolet (UV) radiation. In
contrast, at ground level, it is an air pollutant harmul to human health and ecosystems, and it is
a major component o urban smog. In the troposphere, O3
is also a signicant greenhouse gas.
The threeold increase o the O3
concentration in the northern hemisphere during the past 100
years has made it the third most important contributor to the human enhancement o the global
greenhouse eect, ater CO2 and CH4.
In the troposphere, O3
is ormed by the action o sunlight on O3
precursors that have natural
and anthropogenic sources. These precursors are CH4, nitrogen oxides (NO
X), VOCs and CO. It is
important to understand that reductions in both CH4
and CO emissions have the potential to
substantially reduce O3
concentrations and reduce global warming. In contrast, reducing VOCs
would clearly be benecial but has a small impact on the global scale, while reducing NOX
has
multiple additional eects that result in its net impact on climate being minimal.
Some o the largest emission reductions are obtained using diesel particle lters on high emitting vehicles. The exhibits
above are actual particulate matter (PM) collection samples rom an engine testing laboratory (International Council o
Clean Transportation (ICCT)).
Retrotted withDiesel Oxidation Catalyst (DOC)
(Level 1)
Old technlogy
Little black carbon removal
Little ultrane PM removal
Does not remove lube oil ash
No retrot systemUncontrolled Diesel Exhaust
(Level 1)
Old technlogy
Little black carbon removal
Little ultrane PM removal
Does not remove lube oil ash
Retrotted withPartial Filter
(Level 2)
Little black carbon removal
Little ultrane PM removal
Does not remove lube oil ash
Retrotted withDiesel Particulate Filter (DPF)
(Level 3)
New Technology
Used on all new trucks since 2007
>85% black carbon removal
>85% ultrane removal
>85% lube oil ash removal
Credit:LuisaMolina
Credit:WarrenG
retz/DOE/NREL
Credit:LuisaMolina
Tropospheric ozone is a major constituent o urban smog, let Tokyo, Japan; right Denver, Colorado, USA
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Integrated Assessment o Black Carbon and Tropospheric Ozone
LimitingNear-TermClimate
ChangesandImproving
AirQuality
emissionsofallsubstancesresultingfromthe
fullimplementationoftheidentiedmeasures
throughthetwoglobalcomposition-climate
modelsGISSandECHAM(seeChapter4).
Onehundredpercentimplementationofthe
measuresgloballywasusedtoillustratethe
existingpotentialtoreduceclimateandairqualityimpacts,butthisdoesnotmakeany
assumptionsregardingthefeasibilityoffull
implementationeverywhere.Adiscussion
ofthechallengesinvolvedinwidespread
implementationofthemeasuresfollowsafter
thepotentialbenethasbeendemonstrated.
Achieving large emissionreductions
ThepackagesofpolicymeasuresinTable1werecomparedtoareferencescenario(Table
2).Figure2showstheeffectofthepackages
ofpolicymeasuresandthereferencescenario
relativeto2005emissions.
Thereistremendousregionalvariability
inhowemissionsareprojectedtochange
bytheyear2030underthereference
scenario.EmissionsofCH4amajorO
3
precursorandapotentgreenhousegasare
expectedtoincreaseinthefuture(Figure
2).Thisincreasewilloccurdespitecurrent
andplannedregulations,inlargepartdue
toanticipatedeconomicgrowthandthe
increaseinfossilfuelproductionprojectedto
accompanyit.Incontrast,globalemissionsof
BCandaccompanyingco-emittedpollutants
areexpectedtoremainrelativelyconstant
throughto2030.Regionally,reductionsin
BCemissionsareexpectedduetotighter
standardsonroadtransportandmore
efcientcombustionreplacinguseofbiofuels
intheresidentialandcommercialsectors,
Identifying effective responsemeasures
TheAssessmentidentiedthosemeasures
mostlikelytoprovidecombinedbenets,
taking into account the fact that BC and
O3precursorsareco-emittedwithdifferentgasesandparticles,someofwhichcause
warmingandsomeofwhich,suchasorganic
carbon(OC)andsulphurdioxide(SO2)
leadtocooling.Theselectioncriterionwas
thatthemeasurehadtobelikelytoreduce
globalclimatechangeandalsoprovideair
qualitybenets,so-calledwin-winmeasures.
Thosemeasuresthatprovidedabenet
forairqualitybutincreasedwarmingwere
notincludedintheselectedmeasures.For
example,measuresthatprimarilyreduceemissions of SO
2werenotincluded.
Theidentiedmeasures(Table1)were
chosenfromasubsetofabout2000separate
measuresthatcanbeappliedtosourcesin
IIASAsGAINSmodel.Theselectionwas
basedonthenetinuenceonwarming,
estimatedusingthemetricGlobalWarming
Potential(GWP),ofallofthegasesand
particlesthatareaffectedbythemeasure.
The selection gives a useful indication of the
potentialforrealizingawinforclimate.All
emissionreductionmeasureswereassumed
tobenetairqualitybyreducingparticulate
matterand/orO3concentrations.
Thisselectionprocessidentiedarelatively
smallsetofmeasureswhichnevertheless
provideabout90percentoftheclimate
benetcomparedtotheimplementation
ofall2000measuresinGAINS.Thenal
analysisofthebenetsfortemperature,
humanhealthandcropyieldsconsideredthe
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Summary or Decision Makers
Table 1Measures that improve climate change mitigation and air quality and have a largeemission reduction potential
Measure1 Sector
CH4 measuresExtended pre-mine degasication and recovery and oxidation o CH
4rom
ventilation air rom coal mines
Extraction and
transport o ossil uel
Extended recovery and utilization, rather than venting, o associated gas
and improved control o unintended ugitive emissions rom the production
o oil and natural gas
Reduced gas leakage rom long-distance transmission pipelines
Separation and treatment o biodegradable municipal waste through
recycling, composting and anaerobic digestion as well as landll gas
collection with combustion/utilization Waste management
Upgrading primary wastewater treatment to secondary/tertiary treatment
with gas recovery and overow control
Control o CH4
emissions rom livestock, mainly through arm-scale
anaerobic digestion o manure rom cattle and pigs Agriculture
Intermittent aeration o continuously ooded rice paddies
BC measures (aecting BC and other co-emitted compounds)
Diesel particle lters or road and o-road vehiclesTransport
Elimination o high-emitting vehicles in road and o-road transport
Replacing coal by coal briquettes in cooking and heating stoves
Residential
Pellet stoves and boilers, using uel made rom recycled wood waste or
sawdust, to replace current wood-burning technologies in the residential
sector in industrialized countries
Introduction o clean-burning biomass stoves or cooking and heating in
developing countries2, 3
Substitution o clean-burning cookstoves using modern uels or traditional
biomass cookstoves in developing countries2, 3
Replacing traditional brick kilns with vertical shat kilns and Homan kilns
IndustryReplacing traditional coke ovens with modern recovery ovens, including the
improvement o end-o-pipe abatement measures in developing countries
Ban o open eld burning o agricultural waste2 Agriculture
althoughtheseareoffsettosomeextentby
increasedactivityandeconomicgrowth.
TheregionalBCemissiontrends,therefore,
varysignicantly,withemissionsexpectedto
decreaseinNorthAmericaandEurope,Latin
AmericaandtheCaribbean,andinNortheast
Asia,SoutheastAsiaandthePacic,and
toincreaseinAfricaandSouth,WestandCentralAsia.
The full implementation of the selected
measuresby2030leadstosignicant
reductionsofSLCFemissionsrelativeto
currentemissionsortothe2030emissions
inthereferencescenario(Figure2).Italso
reducesahighproportionoftheemissions
relativetothemaximumreductionfromthe
implementationofall2000orsomeasuresintheGAINSmodel.Themeasuresdesignedto
1 There are measures other than those identied in the table that could be implemented. For example, electric cars would
have a similar impact to diesel particulate lters but these have not yet been widely introduced; orest re controls couldalso be important but are not included due to the diculty in establishing the proportion o res that are anthropogenic.
2 Motivated in part by its eect on health and regional climate, including areas o ice and snow.3 For cookstoves, given their importance or BC emissions, two alternative measures are included.
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reduceBCalsohaveaconsiderableimpact
onOC,totalneparticulatematter(PM25)
andCOemissions,removingmorethanhalf
thetotalanthropogenicemissions.Thelargest
BCemissionreductionsareobtainedthrough
measurescontrollingincompletecombustion
ofbiomassanddieselparticlelters.
ThemajorsourcesofCO2aredifferentfrom
thoseemittingmostBC,OC,CH4
and CO
Eveninthefewcaseswherethereisoverlap,
suchasdieselvehicles,theparticleltersthat
reduceBC,OCandCOhaveminimaleffect
on CO2.ThemeasurestoreduceCO
2over
thenext20years(Table2)thereforehardly
affecttheemissionsofBC,OCorCO.The
inuenceoftheCH4andBCmeasuresisthusthesameregardlessofwhethertheCO
2
measuresareimposedornot.
Reducing near-term globalwarming
TheEarthisprojectedtocontinuethe
rapidwarmingofthepastseveraldecades
and,withoutadditionalmitigationefforts,
underthereferencescenarioglobalmean
temperaturesareprojectedtoriseaboutafurther1.3C(witharangeof0.82.0C)by
themiddleofthiscentury,bringingthetotal
warmingfrompre-industriallevelstoabout
2.2C(Figure3).TheAssessmentshowsthat
themeasurestargetedtoreduceemissions
of BC and CH4couldgreatlyreduceglobal
meanwarmingratesoverthenextfew
decades(Figure3).Figure1showsthatover
halfofthereducedglobalmeanwarming
is achieved by the CH4measuresandthe
remainderbyBCmeasures.Thegreater
condenceintheeffectofCH4measureson
warmingisreectedinthenarrowerrangeof
estimates
Whenallmeasuresarefullyimplemented,
warmingduringthe2030srelativetothe
presentdayisonlyhalfasmuchasifno
measureshadbeenimplemented.Incontrast,evenafairlyaggressivestrategytoreduce
CO2emissionsundertheCO
2measures
scenariodoeslittletomitigatewarming
overthenext2030years.Infact,sulphate
particles,reectingparticlesthatoffsetsome
ofthecommittedwarmingfortheshorttime
theyareintheatmosphere,arederivedfrom
SO2thatisco-emittedwithCO
2in some
ofthehighest-emittingactivities,including
coalburninginlarge-scalecombustionsuch
asinpowerplants.Hence,CO2measuresalonemaytemporarilyenhancenear-term
warmingassulphatesarereduced(Figure3;
Table 2 Policy packages used in the Assessment
Scenario Description1
Reerence Based on energy and uel projections o the International Energy Agency
(IEA) World Energy Outlook 2009 and incorporating all presently agreed
policies aecting emissions
CH4
measures Reerence scenario plus the CH4
measures
BCmeasures Reerence scenario plus the BC measures (the BC measures aect many
pollutants, especially BC, OC, and CO)
CH4
+ BC measures Reerence scenario plus the CH4
and BC measures
CO2
measures Emissions modelled using the assumptions o the IEA World Energy
Outlook 2009 450 Scenario2 and the IIASA GAINS database. Includes CO2
measures only. The CO2
measures aect other emissions, especially SO2
3
CO2
+ CH4
+ BC measures CO2
measures plus CH4
and BC measures
1 In all scenarios, trends in all pollutant emissions are included through 2030, ater which only trends in CO2
are included.2 The 450 Scenario is designed to keep total orcing due to long-lived greenhouse gases (including CH
4in this case) at a
level equivalent to 450 ppm CO2
by the end o the century.3 Emissions o SO
2are reduced by 3540 per cent by implementing CO
2measures. A urther reduction in sulphur emissions
would be benecial to health but would increase global warming. This is because sulphate particles cool the Earth byreecting sunlight back to space.
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Summary or Decision Makers
-90 -70-80 -60 -40 -20 20 40-50 -30 -10 100 30 50
ReferenceBC measures
ReferenceBC measures
ReferenceBC measures
ReferenceBC measures
ReferenceCH4 measuresCH4 + BCmeasures
ReferenceBC measures
ReferenceBC measures
ReferenceBC measures
Change in emissions in 2030 compared to 2005, %
Large-scale combustion Industrial processes
Residential-commercial combustion
Transport Fossil fuel extraction and distribution
Waste /landll
Agriculture
CO2
CO
NOX
SO2
CH4
TotalPM2.5
OC
BC
Figure 2. Percentage change in anthropogenic emissions o the indicated pollutants in 2030 relative to 2005 orthe reerence, CH
4, BC and CH
4+ BC measures scenarios. The CH
4measures have minimal eect on emissions o
anything other than CH4. The identied BC measures reduce a large proportion o total BC, OC and CO emissions.
SO2
and CO2
emissions are hardly aected by the identied CH4
and BC measures, while NOX
and other PM2.5
emissions are aected by the BC measures.
temperaturesintheCO2measuresscenario
areslightlyhigherthanthoseinthereference
scenarioduringtheperiod20202040).
The CO2measuresclearlyleadtolong-term
benets,withadramaticallylowerwarming
ratein2070thanunderthescenariowith
onlynear-termCH4+BCmeasures.Owing
tothelongresidencetimeofCO2
in the
atmosphere,theselong-termbenetswill
only be achieved if CO2emissionreductions
arebroughtinquickly.Inessence,thenear-
termCH4andBCmeasuresexaminedinthis
Assessmentareeffectivelydecoupledfromthe CO
2measuresbothinthattheytarget
differentsourcesectorsandinthattheir
impactsonclimatechangetakeplaceover
differenttimescales.
Near-termwarmingmayoccurinsensitive
regionsandcouldcauseessentiallyirreversible
changes,suchaslossofArcticland-ice,release
of CH4orCO
2fromArcticpermafrostand
speciesloss.Indeed,theprojectedwarming
inthereferencescenarioisgreaterinthe
Arcticthanglobally.Reducingthenear-term
rateofwarminghencedecreasestheriskof
irreversibletransitionsthatcouldinuencethe
globalclimatesystemforcenturies.
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Staying within criticaltemperature thresholds
Adoptionofthenear-termemissioncontrol
measuresdescribedinthisAssessment,togetherwithmeasurestoreduceCO2
emissions,wouldgreatlyimprovethechances
ofkeepingEarthstemperatureincrease
tolessthan2Crelativetopre-industrial
levels(Figure3).WiththeCO2measures
alone,warmingexceeds2Cbefore2050.
EvenwithboththeCO2measuresandCH
4
measuresenvisionedunderthesameIEA450
Scenario,warmingexceeds2Cinthe2060s
(seeChapter5).However,thecombination
of CO2,CH
4,andBCmeasuresholdsthe
temperatureincreasebelow2Cuntilaround
2070.WhileCO2emissionreductionseven
largerthanthoseintheCO2measures
scenariowouldofcoursemitigatemore
warming,actualCO2emissionsoverthepast
decadehaveconsistentlyexceededthemost
pessimisticemissionscenariosoftheIPCC.
Thus,itseemsunlikelythatreductionsmore
stringentthanthoseintheCO2
measures
scenariowilltakeplaceduringthenext
20years.
ExaminingthemorestringentUNFCCC
1.5Cthreshold,theCO2measuresscenario
exceedsthisby2030,whereasthenear-term
measuresproposedintheAssessmentdelay
thatexceedanceuntilafter2040.Again,while
substantiallydeeperearlyreductionsinCO2
emissions than those in the CO2measures
scenariocouldalsodelaythecrossingof
the1.5Ctemperaturethreshold,suchreductionswouldundoubtedlybeevenmore
difculttoachieve.However,adoptionofthe
Assessmentsnear-termmeasures(CH4+BC)
alongwiththeCO2reductionswouldprovide
1900 1950 2000 2050
Temperature(C)relativeto1890-1910
CH4+ BC measures
CO2measures
Reference
CO2 + CH4 + BC
measures
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Figure 3. Observed deviation o temperature to 2009 and projections under various scenarios. Immediate
implementation o the identied BC and CH4
measures, together with measures to reduce CO2
emissions, wouldgreatly improve the chances o keeping Earths temperature increase to less than 2C relative to pre-industrial
levels. The bulk o the benets o CH4
and BC measure are realized by 2040 (dashed line).
Explanatory notes: Actual mean temperature observations through 2009, and projected under various scenarios
thereater, are shown relative to the 18901910 mean temperature. Estimated ranges or 2070 are shown in the bars on
the right. A portion o the uncertainty is common to all scenarios, so that overlapping ranges do not mean there is no
diference, or example, i climate sensitivity is large, it is large regardless o the scenario, so temperatures in all scenarioswould be towards the high-end o their ranges.
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Summary or Decision Makers
asubstantialchanceofkeepingtheEarths
temperatureincreasebelow1.5Cforthenext
30years.
Benets of early implementation
Therewouldclearlybemuchlesswarming
during20202060werethemeasures
implementedearlierratherthanlater(Figure
4).Hencethereisasubstantialnear-term
climatebenetinacceleratingimplementation
oftheidentiedmeasuresevenifsomeof
thesemighteventuallybeadoptedowing
togeneralair-qualityanddevelopment
concerns.Clearlytheearlierimplementation
willalsohavesignicantadditionalhuman
healthandcrop-yieldbenets.
Acceleratedadoptionoftheidentied
measureshasonlyamodesteffectonlong-
termclimatechangeincomparisonwith
waiting20years,however(Figure4).This
reinforcestheconclusionthatreducing
emissions of O3precursorsandBCcanhave
substantialbenetsinthenearterm,but
thatmitigatinglong-termclimatechange
dependsonreducingemissionsoflong-lived
greenhousegasessuchasCO2
Regional climate benets
Whileglobalmeantemperaturesprovide
someindicationofclimateimpacts,
temperaturechangescanvarydramatically
fromplacetoplaceeveninresponseto
relativelyuniformforcingfromlong-lived
greenhousegases.Figure5showsthat
warmingisprojectedtoincreaseforall
regionswithsomevariationunderthereferencescenario,whiletheAssessments
measuresprovidethebenetofreduced
warminginallregions.
Climatechangealsoencompassesmorethan
justtemperaturechanges.Precipitation,
meltingratesofsnowandice,windpatterns,
andcloudsareallaffected,andtheseinturn
haveanimpactonhumanwell-beingby
inuencingfactorssuchaswateravailability,
agricultureandlanduse.
Both O3andBC,aswellasotherparticles,
caninuencemanyoftheprocessesthatlead
totheformationofcloudsandprecipitation.
Theyaltersurfacetemperatures,affecting
evaporation.Byabsorbingsunlightinthe
atmosphere,O3
and especially BC can
affectcloudformation,rainfallandweather
patterns.Theycanchangewindpatternsby
affectingtheregionaltemperaturecontrasts
thatdrivethewinds,inuencingwhere
rainandsnowfall.Whilesomeaspectsof
theseeffectsarelocal,theycanalsoaffect
temperature,cloudiness,andprecipitation
farawayfromtheemissionsources.The
regionalchangesinalltheseaspectsofclimate
willbesignicant,butarecurrentlynotwell
quantied.
Tropical rainfall patterns andthe Asian monsoon
SeveraldetailedstudiesoftheAsian
monsoonsuggestthatregionalforcing
byabsorbingparticlessubstantiallyalters
precipitationpatterns(asexplainedinthe
previoussection).ThefactthatbothO3
and
particlechangesarepredominantlyinthe
northernhemispheremeansthattheycausetemperaturegradientsbetweenthetwo
hemispheresthatinuencerainfallpatterns
throughoutthetropics.Implementationof
themeasuresanalysedinthisAssessment
wouldsubstantiallydecreasetheregional
atmosphericheatingbyparticles(Figure6),
andarehenceverylikelytoreduceregional
shiftsinprecipitation.Asthereductionsof
atmosphericforcingaregreatestoverthe
Indiansub-continentandotherpartsof
Asia,theemissionreductionsmayhaveasubstantialeffectontheAsianmonsoon,
mitigatingdisruptionoftraditionalrainfall
patterns.However,resultsfromglobalclimate
modelsarenotyetrobustforthemagnitude
ortimingofmonsoonshiftsresultingfrom
eithergreenhousegasincreasesorchanges
inabsorbingparticles.Nonetheless,results
fromclimatemodelsprovideexamplesofthe
typeofchangethatmightbeexpected.Shifts
inthetimingandstrengthofprecipitation
canhavesignicantimpactsonhuman
well-beingbecauseofchangesinwater
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3.5
4
4.5
3
2.5
2
1.5
1
0.5
0Temperature(C)relativeto1890-191
0
Africa
Reference
CH4 + BC
measures
Northeast
Asia,
Southeast
Asia and
Pacic
Latin
America
and
Caribbean
North
America
and
Europe
South,
West and
Central Asia
Figure 4. Projected global mean temperature changes or the reerence scenario and or the CH4
and BC
measures scenario with emission reductions starting immediately or delayed by 20 years.
2010 2020 2030 2040
Year
2050 2060 2070
T
emperature(C)relataiveto1890-1910
2
3
0
1
Reference
CH4 + BC measures
from 20302050
CH4 + BC measures
from 20102030
Figure 5. Comparison o regional mean warming over land (C) showing the change in 2070 compared with 2005or the reerence scenario (Table 2) and the CH
4+ BC measures scenario. The lines on each bar show the range o
estimates.
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Summary or Decision Makers
supplyandagriculturalproductivity,drought
andooding.TheresultsshowninFigure
6 suggest that implementation of the BC
measurescouldalsoleadtoaconsiderable
reductioninthedisruptionoftraditional
rainfallpatternsinAfrica.
Decreased warming in polar andother glaciated regions
Implementationofthemeasureswould
substantiallyslow,butnothalt,thecurrent
rapidpaceoftemperatureriseandother
changesalreadyoccurringatthepolesand
high-altitudeglaciatedregions,andthe
reducedwarmingintheseregionswouldlikely
begreaterthanthatseenglobally.Thelargebenetsoccurinpartbecausethesnow/ice
darkeningeffectofBCissubstantiallygreater
thanthecoolingeffectofreectiveparticles
co-emittedwithBC,leadingtogreater
warmingimpactsintheseareasthaninareas
withoutsnowandicecover.
StudiesintheArcticindicatethatitishighly
sensitive both to local pollutant emissions
andthosetransportedfromsourcescloseto
theArctic,aswellastotheclimateimpactofpollutantsinthemid-latitudesofthe
northernhemisphere.Muchoftheneedfor
implementationlieswithinEuropeandNorth
America.Theidentiedmeasurescould
reducewarmingintheArcticbyabout0.7C
(witharangeof0.21.3C)in2040.Thisis
nearlytwo-thirdsoftheestimated1.1C(with
arangeof0.71.7C)warmingprojected
fortheArcticunderthereferencescenario,
andshouldsubstantiallydecreasetheriskof
globalimpactsfromchangesinthissensitive
region,suchasseaiceloss,whichaffects
globalalbedo,andpermafrostmelt.Although
notidentiedasameasureforuseinthis
Assessment,thecontrolofborealforestres
mayalsobeimportantinreducingimpactsin
theArctic.
TheAntarcticisafarlessstudiedregionintermsofSLCFimpacts.However,there
arestudiesdemonstratingBCdeposition
evenincentralportionsofthecontinent,
andreductionsinO3and CH
4should
slowwarminginplacesliketheAntarctic
Peninsula,currentlythespotontheglobe
showingthemostrapidtemperaturerise
of all
TheHimalayasandtheTibetanPlateauare
regionswhereBCislikelytohaveseriousimpacts.InthehighvalleysoftheHimalayas,
forexample,BClevelscanbeashighasin
50
0
-50
-20 -10 -4 -3 -2 -1 1
-100 0 100 -100 0 100
50
0
-50
W/m2
GISS ECHAM
Figure 6. Change in atmospheric energy absorption (Watts per square metre, W/m2 as annual mean), an
important actor driving tropical rainall and the monsoons resulting rom implementation o BC measures.The changes in absorption o energy by the atmosphere are linked with changes in regional circulation and
precipitation patterns, leading to increased precipitation in some regions and decreases in others. BC solar
absorption increases the energy input to the atmosphere by as much as 515 per cent, with the BC measures
removing the bulk o that heating. Results are shown or two independent models to highlight the similarity in
the projections o where large regional decreases would occur.
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amid-sizedcity.Reducingemissionsfrom
localsourcesandthosecarriedbylong-range
transportshouldlowerglacialmeltinthese
regions,decreasingtheriskofimpactssuch
ascatastrophicglaciallakeoutbursts.
Benets of the measures forhuman health
Fineparticulatematter(measuredasPM25,
whichincludesBC)andground-level
O3
damage human health PM25
causes
prematuredeathsprimarilyfromheart
diseaseandlungcancer,andO3exposure
causesdeathsprimarilyfromrespiratory
illness.Thehealthbenetestimatesin
the Assessmentarelimitedtochangesinthesespeciccausesofdeathandinclude
uncertaintyintheestimationmethods.
However,thesepollutantsalsocontribute
signicantlytootherhealthimpacts
includingacuteandchronicbronchitis
andotherrespiratoryillness,non-fatal
heartattacks,lowbirthweightandresults
inincreasedemergencyroomvisitsand
hospitaladmissions,aswellaslossofwork
and school days
Underthereferencescenario,thatis,
withoutimplementationoftheidentied
measures,changesinconcentrationsof
PM25
and O3in2030,relativeto2005,
wouldhavesubstantialeffectsgloballyon
prematuredeathsrelatedtoairpollution.
Byregion,prematuredeathsfromoutdoor
pollutionareprojectedtochangeinline
withemissions.Thelatterareexpectedto
decreasesignicantlyoverNorthAmerica
andEuropeduetoimplementationoftheexistingandexpectedlegislation.
OverAfricaandLatinAmericaandthe
Caribbean,thenumberofprematuredeaths
fromthesepollutantsisexpectedtoshow
modestchangesunderthereferencescenario
(Figure7).OverNortheastAsia,Southeast
AsiaandPacic,prematuredeathsare
projectedtodecreasesubstantiallydueto
reductionsinPM25insomeareas.However,
inSouth,WestandCentralAsia,premature
deathsareprojectedtorisesignicantlydue
togrowthinemissions.
Incontrasttothereferencescenario,full
implementationofthemeasuresidentied
in the Assessmentwouldsubstantially
improveairqualityandreducepremature
deathsgloballyduetosignicantreductions
inindoorandoutdoorairpollution.The
reductionsinPM25concentrationsresulting
fromtheBCmeasureswould,by2030,
avoidanestimated0.74.6millionannual
prematuredeathsduetooutdoorairpollution
(Figure1).
Regionally,implementationoftheidentied
measureswouldleadtogreatlyimproved
airqualityandfewerprematuredeaths,
especiallyinAsia(Figure7).Infact,more
than80percentofthehealthbenetsofimplementingallmeasuresoccurinAsia.
Thebenetsarelargeenoughforallthe
worseningtrendsinhumanhealthdueto
outdoorairpollutiontobereversedand
turnedintoimprovements,relativeto2005.
InAfrica,thebenetissubstantial,although
notasgreatasinAsia.
Benets of the measures forcrop yields
Ozoneistoxictoplants.Avastbody
ofliteraturedescribesexperimentsand
observationsshowingthesubstantialeffects
of O3onvisibleleafhealth,growthand
productivityforalargenumberofcrops,
treesandotherplants.Ozonealsoaffects
vegetationcompositionanddiversity.
Globally,thefullimplementationofCH4
measuresresultsinsignicantreductionsin
O3concentrationsleadingtoavoidedyield
lossesofabout25milliontonnesoffourstaplecropseachyear.Theimplementation
oftheBCmeasureswouldaccountforabout
afurther25milliontonnesofavoidedyield
lossesincomparisonwiththereference
scenario(Figure1).Thisisduetosignicant
reductionsinemissionsoftheprecursors
CO,VOCsandNOXthatreduceO
3
concentrations.
Theregionalpictureshowsconsiderable
differences.Underthereferencescenario,
O3concentrationsoverNortheast,Southeast
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Summary or Decision Makers
AsiaandPacicareprojectedtoincrease,
resultinginadditionalcropyieldlosses
(Figures7and8).InSouth,WestandCentral
Asia,bothhealthandagriculturaldamage
areprojectedtorise(Figure8).Damageto
agricultureisprojectedtodecreasestrongly
overNorthAmericaandEuropewhile
changingminimallyoverAfricaandLatin
AmericaandtheCaribbean.Forthewhole
Asianregionmaizeyieldsshowadecreaseof
115percent,whileyieldsdecreasebyless
than5percentforwheatandrice.These
yieldlossestranslateintonearly40million
tonnesforallcropsforthewholeAsianregion,
reectingthesubstantialcultivatedarea
exposedtoelevatedO3concentrationsinIndia
inparticulartheIndo-GangeticPlainregion.Riceproductionisalsoaffected,particularly
inAsiawhereelevatedO3concentrationsare
likelytocontinuetoincreaseto2030.Yield
lossvaluesforriceareuncertain,however,
duetoalackofexperimentalevidenceon
concentration-responsefunctions.Incontrast,
theEuropeanandNorthAmericanregional
analysessuggestthatallcropswillseean
improvementinyieldsunderthereference
scenariobetween2005and2030.Even
greaterimprovementswouldbeseenuponimplementationofthemeasures.
Theidentiedmeasuresleadtogreatly
reducedO3concentrations,withsubstantial
benetstocropyields,especiallyinAsia
(Figure8).Thebenetsofthemeasuresare
largeenoughtoreversealltheworsening
trendsseeninagriculturalyieldsandturn
themintoimprovements,relativeto2005,
withtheexceptionofcropyieldsinNortheast
andSoutheastAsiaandPacic.Eveninthat
case,thebenetsoffullimplementationare
quitelarge,withthemeasuresreducingby
60percentthecroplossesenvisagedinthe
referencescenario.
ItshouldbestressedthattheAssessments
analysesincludeonlythedirecteffectof
changesinatmosphericcompositiononhealthandagriculturethroughchangesinexposure
topollutants.Assuch,theydonotinclude
thebenetsthatavoidedclimatechange
wouldhaveonhumanhealthandagriculture
duetofactorssuchasreduceddisruptionof
precipitationpatterns,dimming,andreduced
frequencyofheatwaves.Furthermore,even
thedirectinuenceonyieldsarebasedon
estimatesforonlyfourstaplecrops,and
impactsonleafycrops,productivegrasslands
andfoodqualitywerenotincluded,sothatthecalculatedvaluesarelikelytobean
Figure 7. Comparison o premature mortality (millions o premature deaths annually) by region, showing the
change in 2030 in comparison with 2005 or the reerence scenario emission trends and the reerence plus CH4 +BC measures. The lines on each bar show the range o estimates.
1.5
2
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
-3
Reference
Reference +
CH4 + BC
measures
Africa Northeast
Asia,
Southeast
Asia and
Pacic
Latin
America
and
Caribbean
North
America
and
Europe
South,
West and
Central Asia
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underestimateofthetotalimpact.Inaddition,
extrapolationofresultsfromanumberof
experimentalstudiestoassessO3
impacts on
ecosystemsstronglysuggeststhatreductions
in O3couldleadtosubstantialincreasesinthe
netprimaryproductivity.Thiscouldhavea
substantialimpactoncarbonsequestration,
providingadditionalclimatebenets.
Relative importance andscientic condence in themeasures
Methanemeasureshavealargeimpactonglobalandregionalwarming,whichis
achievedbyreducingthegreenhousegases
CH4
and O3 The climate mitigation impacts
of the CH4measuresarealsothemostcertain
becausethereisahighdegreeofcondence
inthewarmingeffectsofthisgreenhouse
gas.ThereducedmethaneandhenceO3
concentrationsalsoleadtosignicantbenets
forcropyields.
TheBCmeasuresidentiedherereduce
concentrationsofBC,OCandO3(largely
throughreductionsinemissionsofCO).
ThewarmingeffectofBCandO3
and
thecompensatingcoolingeffectofOC,
introduceslargeuncertaintyintheneteffect
ofsomeBCmeasuresonglobalwarming
(Figure1).UncertaintyintheimpactofBC
measuresisalsolargerthanthatforCH4
becauseBCandOCcaninuenceclouds
that have multiple effects on climate that
arenotfullyunderstood.Thisuncertainly
inglobalimpactsisparticularlylargeforthe
Figure 8. Comparison o crop yield losses (million tonnes annually o our key crops wheat, rice, maize and soy
combined) by region, showing the change in 2030 compared with 2005 or the reerence emission trends and thereerence with CH
4+ BC measures. The lines on each bar show the range o estimates.
100
50
0
-50
-100
-150
Africa
Reference
CH4 + BC
measures
Northeast
Asia,
Southeast
Asia and
Pacic
Latin
America
and
Caribbean
North
America
and
Europe
South,
West and
Central Asia
The measures identied in the Assessment include
replacement o traditional cookstoves, such as that
shown here, with clean burning stoves which wouldsubstantially improve air quality and reduce prematuredeaths due to indoor and outdoor air pollution.
Credit:Ve
erabhadranRamanathan
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Summary or Decision Makers
measuresconcerningbiomasscookstovesand
openburningofbiomass.Hencewithrespecttoglobalwarming,thereismuchhigher
condenceformeasuresthatmitigatediesel
emissionsthanbiomassburningbecausethe
proportionofco-emittedcoolingOCparticles
ismuchlowerfordiesel.
Ontheotherhand,thereishighercondence
thatBCmeasureshavelargeimpactson
humanhealththroughreducingconcentrations
ofinhalableparticles,oncropyieldsthrough
reducedO3,andonclimatephenomenasuch
astropicalrainfall,monsoonsandsnow-ice
melt.Theseregionalimpactsarelargely
independentofthemeasuresimpacton
globalwarming.Infact,regionally,biomass
cookstovesandopenbiomassburningcan
havemuchlargereffectsthanfossilfuels.This
isbecauseBCdirectlyincreasesatmospheric
heatingbyabsorbingsunlight,which,
accordingtonumerouspublishedstudies,
affectsthemonsoonandtropicalrainfall,and
thisislargelyseparatefromtheeffectofco-
emittedOC.ThesameconclusionapplieswithrespecttotheimpactofBCmeasuresonsnow
andice.BC,becauseitisdark,signicantly
increasesabsorptionofsunlightbysnowand
icewhenitisdepositedonthesebrightsurfaces.
OCthatisdepositedalongwithBChasvery
littleeffectonsunlightreectedbysnowand
icesincethesesurfacesarealreadyverywhite.
Henceknowledgeoftheseregionalimpacts
is,insomecases,morerobustthantheglobal
impacts,andwithrespecttoreducingregional
impacts,alloftheBCmeasuresarelikelytobesignicant.Condenceisalsohighthatalarge
proportionofthehealthandcropbenets
wouldberealizedinAsia.
Mechanisms for rapidimplementation
InDecember2010thePartiestothe
UNFCCCagreedthatwarmingshouldnot
exceed2Cabovepre-industriallevelsduring
thiscentury.ThisAssessmentshowsthat
measurestoreduceSLCFs,implemented
incombinationwithCO2controlmeasures,
wouldincreasethechancesofstayingbelow
the2Ctarget.Themeasureswouldalso
slowtherateofnear-termtemperaturerise
andalsoleadtosignicantimprovements
inhealth,decreaseddisruptionofregional
precipitationpatternsandwatersupply,and
inimprovedfoodsecurity.Theimpactsofthe
measuresontemperaturechangearefeltover
largegeographicalareas,whiletheairquality
impactsaremorelocalizedneartheregions
wherechangesinemissionstakeplace.
Therefore,areasthatcontroltheiremissions
willreceivethegreatesthumanhealthandfoodsupplybenets;additionallymanyofthe
climatebenetswillbefeltclosetotheregion
taking action
Thebenetswouldberealizedinthenear
term,therebyprovidingadditionalincentives
toovercomenancialandinstitutional
hurdlestotheadoptionofthesemeasures.
Countriesinallregionshavesuccessfully
implementedtheidentiedmeasuresto
somedegreeformultipleenvironmentanddevelopmentobjectives.Theseexperiences
Widespread haze over the Himalayas where BC
concentrations can be as high as in mid-sized cities.
Reducing emissions should lower glacial melt and
decrease the risk o outbursts rom glacial lakes.
Credit:Ve
erabhadranRamanathan
Credit:GovindJoshi
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provideaconsiderablebodyofknowledge
andpotentialmodelsforothersthatwishto
take action
Inmostcountries,mechanismsarealready
inplace,albeitatdifferentlevelsofmaturity,
toaddresspublicconcernregardingair
pollutionproblems.Mechanismstotackle
anthropogenicgreenhousegasesareless
welldeployed,andsystemstomaximize
theco-benetsfromreducingairpollution
andmeasurestoaddressclimatechangeare
virtuallynon-existent.Coordinationacross
institutionstoaddressclimate,airpollution,
energyanddevelopmentpolicyisparticularlyimportanttoenhanceachievementofallthese
goals simultaneously
ManyBCcontrolmeasuresrequire
implementationbymultipleactorsondiffuse
emissionsourcesincludingdieselvehicles,
eldburning,cookstovesandresidential
heating.Althoughairqualityandemission
standardsexistforparticulatematterinsome
regions,theymayormaynotreduceBC,
andimplementationremainsachallenge.Relevance,benetsandcostsofdifferent
Field burning o agricultural waste is a common way to dispose o crop residue in many regions.
To the naked eye, no emissions rom an oil storage tank are visible (let), but with the aid o an inrared camera,escaping CH
4is evident (right).
Credit:USEPA
Credit:BrianYap
measuresvaryfromregiontoregion.
Manyofthemeasuresentailcostsavings
butrequiresubstantialupfrontinvestments.
Accountingforairquality,climateand
developmentco-benetswillbekeytoscaling
up implementation
Methaneisoneofthesixgreenhousegases
governedbytheKyotoProtocol,butthereare
noexplicittargetsforit.ManyCH4measures
arecost-effectiveanditsrecoveryis,inmany
cases,economicallyprotable.Therehave
been many Clean Development Mechanism
(CDM)projectsinkeyCH4emittingsectorsin
thepast,thoughfewsuchprojectshavebeenlaunchedinrecentyearsbecauseoflackof
nancing.
Casestudiesfrombothdevelopedand
developingcountries(Box3)showthatthere
aretechnicalsolutionsavailabletodeliver
allofthemeasures(seeChapter5).Given
appropriatepolicymechanismsthemeasures
canbeimplemented,buttoachievethe
benetsatthescaledescribedmuchwider
implementationisrequired.
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Summary or Decision Makers
Box3:Casestudiesof implementationof measuresCH
4measures
Landll biogas energy
Landll CH4 emissions contribute 10 per cent o the total greenhouse gas emissions in Mexico.
Bioenergia de Nuevo Lon S.A. de C.V. (BENLESA) is using landll biogas as uel. Currently, the
plant has an installed capacity o 12.7 megawatts. Since its opening in September 2003, it has
avoided the release o more than 81 000 tonnes o CH4, equivalent to the reduction in emissions
o 1.7 million tonnes o CO2, generating 409 megawatt hours o electricity. A partnership between
government and a private company turned a liability into an asset by converting landll gas (LFG)
into electricity to help drive the public transit system by day and light city streets by night. LFG
projects can also be ound in Armenia, Brazil, China, India, South Arica, and other countries.
Recovery and faring rom oil and natural gas production
Oil drilling oten brings natural gas, mostly CH4, to the surace along with the oil, which is oten
vented to the atmosphere to maintain sae pressure in the well. To reduce these emissions,
associated gas may be ared and converted to CO2, or recovered, thus eliminating most o its
warming potential and removing its ability to orm ozone (O3). In India, Oil India Limited (OIL), a
national oil company, is undertaking a project to recover the gas, which is presently ared, rom
the Kumchai oil eld, and send it to a gas processing plant or eventual transport and use in the
natural gas grid. Initiatives in Angola, Indonesia and other countries are aring and recovering
associated gas yielding large reductions in CH4
emissions and new sources o uel or local markets.
Livestock manure management
In Brazil, a large CDM project in the state o Mina Gerais seeks to improve waste management
systems to reduce the amount o CH4
and other greenhouse gas emissions associated with
animal efuent. The core o the project is to replace open-air lagoons with ambient temperature
anaerobic digesters to capture and combust the resulting biogas. Over the course o a 10-yearperiod (20042014) the project plans to reduce CH4
and other greenhouse gas emissions by a total
o 50 580 tonnes o CO2
equivalent. A CDM project in Hyderabad, India, will use the poultry litter
CH4
to generate electricity which will power the plant and supply surplus electricity to the Andhra
Pradesh state grid.
Farm scale anaerobic digestion o manure rom cattle is one o the key CH4 measures
Credit:RaphalV/fickr
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Box3:Casestudiesof implementationof measures(continued)BC measures
Diesel particle lters
In Santiago, municipal authorities, responding to public concern on air pollution, adopted a new
emissions standard or urban buses, requiring installation o diesel particle lters (DPFs). Currently
about one-third o the eet is equipped with lters; it is expected that the entire eet will be
retrotted by 2018. New York City adopted regulations in 2000 and 2003 requiring use o DPFs in
city buses and o-road construction equipment working on city projects. London tted DPFs to
the citys bus eet over several years beginning in 2003. Low emission zones in London and other
cities create incentives or diesel vehicle owners to retrot with particle lters, allowing them to
drive within the city limits. Implementation in developing regions will require greater availability o
low sulphur diesel, which is an essential prerequisite or using DPFs.
Improved brick kilns
Small-scale traditional brick kilns are a signicant source o air pollution in many developing
countries; there are an estimated 20 000 in Mexico alone, emitting large quantities o particulates.
An improved kiln design piloted in Ciudad Jurez, near the border with the United States o
America, improved eciency by 50 per cent and decreased particulate pollution by 80 per cent.
In the Bac Ninh province o Viet Nam, a project initiated with the aim o reducing ambient air
pollution levels and deposition on surrounding rice elds piloted the use o a simple limestone
scrubbing emissions control device and demonstrated how a combination o regulation, economic
tools, monitoring and technology transer can signicantly improve air quality.
A traditional brick kiln (let) and an improved (right) operating in Mexico.
Potential international
regulatory responses
Internationalresponseswouldfacilitate
rapidandwidespreadimplementationof
themeasures.Sincealargeportionofthe
impactsofSLCFsonclimate,health,food
securityandecosystemsisregionalorlocal
innature,regionalapproachesincorporating
nationalactionscouldprovepromisingfor
theircost-effectivereduction.Thisapproach
isstillinitsveryearlystageinmostregionsof
theworld.Forexample,theConventiononLong-RangeTransboundaryAirPollution
Credit:AlbaCorralAvitia
Credit:RobertMarquez
(CLRTAP)recentlyagreedtoaddressBCin
therevisionoftheGothenburgProtocolin2011andtoconsidertheimpactsofCH
4as
an O3precursorinthelongerterm.
Otherregionalagreements(Box4)arefairly
new,andpredominantlyconcentrateon
scienticcooperationandcapacitybuilding.
Thesearrangementsmightserveasa
platformfromwhichtoaddresstheemerging
challengesrelatedtoairpollutionfromBC
andtroposphericO3andprovidepotential
vehiclesfornance,technologytransferandcapacitydevelopment.Sharinggoodpractices
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Summary or Decision Makers
onaninternationalscale,asisoccurring
withintheArcticCouncil,inacoordinated
waycouldprovideahelpfulwayforward.
ThisAssessmentdidnotassessthecost-
effectivenessofdifferentidentiedmeasures
orpolicyoptionsunderdifferentnational
circumstances.Doingsowouldhelpto
informnationalairqualityandclimatepolicy
makers,andsupportimplementationona
widerscale.Furtherstudyandanalysesofthe
localapplicationofBCandtroposphericO3
reductiontechnologies,costsandregulatory
approachescouldcontributetoadvancing
adoption of effective action at multiple levels
Thisworkwouldbebestdonebasedonlocal
knowledge.Likewisefurtherevaluationofthe
regionalandglobalbenetsofimplementing
specicmeasuresbyregionwouldhelpto
bettertargetpolicyefforts.Insupportofthese
efforts,additionalmodellingandmonitoring
andmeasurementactivitiesareneededtoll
remainingknowledgegaps.
Opportunities for internationalnancing and cooperation
Thelargestbenetswouldbedeliveredin
regionswhereitisunlikelythatsignicant
nationalfundswouldbeallocatedtothese
issuesduetootherpressingdevelopment
needs.Internationalnancingandtechnology
supportwouldcatalyseandaccelerate
theadoptionoftheidentiedmeasuresatsub-national,nationalandregionallevels,
especiallyindevelopingcountries.Financing
wouldbemosteffectiveifspecicallytargeted
towardspollutionabatementactionsthat
maximizeairqualityandclimatebenets.
FundsandactivitiestoaddressCH4(such
astheGlobalMethaneInitiative;andthe
GlobalMethaneFundorPrototypeMethane
FinancingFacility)andcookstoves(theGlobal
AllianceforCleanCookstoves)existorare
underconsiderationandmayserveasmodels
forothersectors.Expandedactionwilldepend
ondonorrecognitionoftheopportunity
representedbySLCFreductionsasahighly
effectivemeanstoaddressnear-termclimate
change both globally and especially in
sensitiveregionsoftheworld.
BlackcarbonandtroposphericO3
may also
beconsideredaspartofotherenvironment,
developmentandenergyinitiativessuchas
bilateralassistance,theUNDevelopment
AssistanceFramework,theWorldBankEnergyStrategy,thePovertyandEnvironment
InitiativeofUNEPandtheUnitedNations
DevelopmentProgramme(UNDP),
interagencycooperationinitiativesintheUN
systemsuchastheEnvironmentManagement
GroupandUNEnergy,theUNFoundation,
andtheconsiderationbytheUNConference
onSustainableDevelopment(Rio+20)of
theinstitutionalframeworkforsustainable
development.These,andothers,couldtake
advantageoftheopportunitiesidentiedintheAssessmenttoachievetheirobjectives.
Box4:Examplesof regionalatmosphericpollution
agreementsThe Convention on Long-Range Transboundary Air Pollution (CLRTAP) is a mature policy
ramework covering Europe, Central Asia and North America. Similar regional agreements have
emerged in the last decades in other parts o the world. The Mal Declaration on Control and
Prevention o Air Pollution and its Likely Transboundary Eects or South Asia was agreed in
1998 and addresses air quality including tropospheric O3
and particulate matter. The Association
o Southeast Asian Nations (ASEAN) Haze Protocol is a legally binding agreement addresses
particulate pollution rom orest res in Southeast Asia. In Arica there are a number o ramework
agreements between countries in southern Arica (Lusaka Agreement), in East Arica (Nairobi
Agreement); and West and Central Arica (Abidjan Agreement). In Latin America and the Caribbean
a ministerial level intergovernmental network on air pollution has been ormed and there is a drat
ramework agreement and ongoing collaboration on atmospheric issues under UNEPs leadership.
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ConcludingRemarks
TheAssessmentestablishestheclimateco-
benetsofair-qualitymeasuresthataddress
blackcarbonandtroposphericozoneand
itsprecursors,especiallyCH4
and CO The
measuresidentiedtoaddresstheseshort-
livedclimateforcershavebeensuccessfully
triedaroundtheworldandhavebeen
showntodeliversignicantandimmediate
developmentandenvironmentalbenetsin
thelocalareasandregionswheretheyare
implemented
Costsandbenetsoftheidentiedmeasures
areregionspecic,andimplementation
oftenfacesnancial,regulatoryand
institutionalbarriers.However,widespread
implementationoftheidentiedmeasures
canbeeffectivelyleveragedbyrecognizing
thatnear-termstrategiescanslowtherate
ofglobalandregionalwarming,improving
ourchancesofkeepingglobaltemperature
increasebelowboundsthatsignicantlylowertheprobabilityofmajordisruptiveclimate
events.Suchleverageshouldspurmultilateral
initiativesthatfocusonlocalprioritiesand
contributetotheglobalcommongood.
ItisneverthelessstressedthatthisAssessment
doesnotinanywaysuggestpostponing
immediateandaggressiveglobalactionon
anthropogenicgreenhousegases;infactit
requiressuchactiononCO2 This Assessment
concludesthatthechanceofsuccesswithsuchlonger-termmeasurescanbegreatly
enhancedbysimultaneouslyaddressingshort-
livedclimateforcers.
ThebenetsidentiedinthisAssessmentcan
berealisedwithaconcertedeffortgloballyto
reducetheconcentrationsofblackcarbonand
troposphericozone.Astrategytoachievethis,
whendevelopedandimplemented,willlead
toconsiderablebenetsforhumanwell-being.
Aerosol measurement instruments
Credit:ChristianLagerek
Credit:JohnOgren,NOAA
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Summary or Decision Makers
Glossary
Aerosol A collection o airborne solid or liquid particles (excluding pure water),
with a typical size between 0.01 and 10 micrometers (m) and residing in
the atmosphere or at least several hours. Aerosols may be o either natu-ral or anthropogenic origin. Aerosols may inuence climate in two ways:
directly through scattering or absorbing radiation, and indirectly through
acting as condensation nuclei or cloud ormation or modiying the opti-
cal properties and lietime o clouds.
Biofuels Biouels are non-ossil uels. They are energy carriers that store the energy
derived rom organic materials (biomass), including plant materials and
animal waste.
Biomass In the context o energy, the term biomass is oten used to reer to organic
materials, such as wood and agricultural wastes, which can be burned to
produce energy or converted into a gas and used or uel.
Black carbon Operationally defned aerosol species based on measurement o lightabsorption and chemical reactivity and/or thermal stability. Black carbon
is ormed through the incomplete combustion o ossil uels, biouel, and
biomass, and is emitted in both anthropogenic and naturally occurring
soot. It consists o pure carbon in several linked orms. Black carbon warms
the Earth by absorbing heat in the atmosphere and by reducing albedo,
the ability to reect sunlight, when deposited on snow and ice.
Carbon
sequestration
The uptake and storage o carbon. Trees and plants, or example, absorb
carbon dioxide, release the oxygen and store the carbon.
Fugitive
emissions
Substances (gas, liquid, solid) that escape to the air rom a process or a
product without going through a smokestack; or example, emissions o
methane escaping rom coal, oil, and gas extraction not caught by a cap-
ture system.
Global
warming
potential
(GWP)
The global warming potential o a gas or particle reers to an estimate o
the total contribution to global warming over a particular time that results
rom the emission o one unit o that gas or particle relative to one unit o
the reerence gas, carbon dioxide, which is assigned a value o one.
High-emitting
vehicles
Poorly tuned or deective vehicles (including malunctioning emission
control system), with emissions o air pollutants (including particulate
matter) many times greater than the average.
Hoffman kiln Homann kilns are the most common kiln used in production o bricks. A
Homann kiln consists o a main fre passage surrounded on each side byseveral small rooms which contain pallets o bricks. Each room is connect-
ed to the next room by a passageway carrying hot gases rom the fre. This
design makes or a very efcient use o heat and uel.
Incomplete
combustion
A reaction or process which entails only partial burning o a uel. Combus-
tion is almost always incomplete and this may be due to a lack o oxygen
or low temperature, preventing the complete chemical reaction.
Oxidation The chemical reaction o a substance with oxygen or a reaction in which
the atoms in an element lose electrons and its valence is correspondingly
increased.
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Ozone Ozone, the triatomic orm o oxygen (O3), is a gaseous atmospheric constit-
uent. In the troposphere, it is created both naturally and by photochemical
reactions involving gases resulting rom human activities (it is a primary
component o photochemical smog). In high concentrations, tropospheric
ozone can be harmul to a wide range o living organisms. Troposphericozone acts as a greenhouse gas. In the stratosphere, ozone is created by
the interaction between solar ultraviolet radiation and molecular oxygen.
Stratospheric ozone provides a shield rom ultraviolet B (UVB) radiation.
Ozone
precursor
Chemical compounds, such as carbon monoxide (CO), methane (CH4),
non-methane volatile organic compounds (NMVOC), and nitrogen oxides
(NOX), which in the presence o solar radiation react with other chemical
compounds to orm ozone in the troposphere.
Particulate
matter
Very small pieces o solid or liquid matter such as particles o soot, dust, or
other aerosols.
Pre-industrial Prior to widespread industrialisation and the resultant changes in the
environment. Typically taken as the period beore 1750.
Radiation Energy transer in the orm o electromagnetic waves or particles that
release energy when absorbed by an object.
Radiative
forcing
Radiative orcing is a measure o the change in the energy balance o the
Earth-atmosphere system with space. It is defned as the change in the
net, downward minus upward, irradiance (expressed in Watts per square
metre) at the tropopause due to a change in an external driver o climate
change, such as, or example, a change in the concentration o carbon
dioxide or the output o the Sun.
Smog Classically a combination o smoke and og in which products o com-
bustion, such as hydrocarbons, particulate matter and oxides o sulphurand nitrogen, occur in concentrations that are harmul to human beings
and other organisms. More commonly, it occurs as photochemical smog,
produced when sunlight acts on nitrogen oxides and hydrocarbons to
produce tropospheric ozone.
Stratosphere Region o the atmosphere between the troposphere and mesosphere,
having a lower boundary o approximately 8 km at the poles to 15 km at
the equator and an upper boundary o approximately 50 km. Depending
upon latitude and season, the temperature in the lower stratosphere can
increase, be isothermal, or even decrease with altitude, but the tempera-
ture in the upper stratosphere generally increases with height due to
absorption o solar radiation by ozone.Trans-
boundary
movement
Movement rom an area under the national jurisdiction o one State to or
through an area under the national jurisdiction o another State or to or
through an area not under the national jurisdiction o any State.
Transport
(atmospheric)
The movement o chemical species through the atmosphere as a result o
large-scale atmospheric motions.
Troposphere The lowest part o the atmosphere rom the surace to about 10 km in
altitude in mid-latitudes (ranging rom 9 km in high latitudes to 16 km in
the tropics on average) where clouds and weather phenomena occur. In
the troposphere temperatures generally decrease with height.
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Summary or Decision Makers
Acronyms and Abbreviations
ASEAN Association o Southeast Asian Nations
BC black carbon
BENLESA Latin America Bioenergia de Nuevo Lon S.A. de C.V.CDM Clean Development Mechanism
CH4
methane
CLRTAP Convention on Long-Range Transboundary Air Pollution
CO carbon monoxide
CO2
carbon dioxide
DPF diesel particle lter
ECHAM Climate-chemistry-aerosol model developed by the Max Planck Institute in Ham-
burg, Germany
G8 Group o Eight: Canada, France, Germany, Italy, Japan, Russian Federation, United
Kingdom, United States
GAINS Greenhouse Gas and Air Pollution Interactions and SynergiesGISS Goddard Institute or Space Studies
GWP global warming potential
IEA International Energy Agency
IIASA International Institute or Applied System Analysis
IPCC Intergovernmental Panel on Climate Change
LFG landll gas
NASA National Aeronautics and Space Administration
NOX
nitrogen oxides
O3
ozone
OC organic carbon
OIL Oil India Limited
PM particulate matter (PM2.5
has a diameter o 2.5m or less)
ppm parts per million
SLCF short-lived climate orcer
SO2
sulphur dioxide
UN United Nations
UNDP United Nations Development Programme
UNEP United Nations Environment Programme
UNFCCC United Nations Framework Convention on Climate Change
UV ultraviolet
VOC volatile organic compoundWMO World Meteorological Organization
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Acknowledgements
The United Nations Environment Programme and World Meteorological Organization
would like to thank the Assessment Chair and Vice-Chairs, the members o the High-level
Consultative Group, all the lead and contributing authors, reviewers and review editors, and
the coordination team or their contribution to the development o this Assessment.
The ollowing individuals have provided input to the Assessment. Authors, reviewers
and review editors have contributed to this report in their individual capacity and their
organizations are mentioned or identication purposes only.
Chair: Drew Shindell (National Aeronautics and Space Administration Goddard Institute or
S