What do we know

about reducing

greenhouse

gas emissions?

A simplified guide to the IPCC’s

“Climate Change 2001: Mitigation”

Information Unit for ConventionsUnited Nations Environment

ProgrammeCH-1219 Geneva, Switzerland

Tel: +41 (22) 917 82 44 / 917 81 96Fax: + 41 (22) 797 34 64

Web: www.unep.ch/conventions

This guide has been funded and produced by the United Nations Environment Programmewith additional support from the Government of the Netherlands. For more information,please contact UNEP, Information Unit for Conventions, International Environment House, 15 chemin des Anémones, CH-1219 Châtelaine (Geneva), Switzerland; iuc@unep.ch; or +41-22-917-8244/8196. See also www.ipcc.ch, www.unep.org, and www.wmo.ch.

All figures in this booklet are from “Climate Change 2001: Mitigation”, Intergovernmental Panel on Climate Change, Cambridge University Press, 2001.

GE.0201807/E - September 2002 - 2000

1

What do we know about reducing greenhouse gasemissions?A simplified guide to the IPCC’s “Climate Change2001: Mitigation”

Foreword

The concepts and conclusions presented by“Climate Change 2001: Mitigation”, part ofthe ground-breaking Third AssessmentReport by the WMO/UNEP IntergovernmentalPanel on Climate Change, are central toglobal action on climate change. While thefirst two volumes of the Report detail whatis known about causes, impacts, and adap-tation – thus highlighting the need for action– the third volume on mitigation analyseshow to take action by limiting net greenhousegas emissions. Policymakers at the nationaland local levels, business leaders, communityleaders, and concerned individuals and organ-izations can use these tools to make a realdifference.

This simplified guide briefly introduces andexplains what Working Group Three – led byits co-chairs, Prof. Ogunlade Davidson ofSierra Leone and Dr. Bert Metz of TheNetherlands – found when it assessed thepeer-reviewed expert literature on mitigation.The guide is not an official document andhas been neither approved nor accepted bythe IPCC. Instead, it represents an effort tomake the hundreds of pages of detailedand technical text that constitute the volumeon “Mitigation” more accessible to a broaderaudience. It is my sincere hope that you willfind this introduction useful in its own rightand that it will serve as a stepping stone tofurther understanding and action.

Klaus TöpferExecutive DirectorUnited Nations EnvironmentProgramme

Wha

t do w

e kno

w ab

out r

educ

ing g

reen

hous

e gas

emiss

ions

?

2

The Intergovernmental Panel on ClimateChange was established in 1988 by theWorld Meteorological Organization (WMO)and the United Nations EnvironmentProgramme (UNEP). The IPCC does not conduct new research. Instead, its mandateis to make policy-relevant assessments ofthe existing world-wide literature on the scientific, technical and socio-economicaspects of climate change. Most of thisexpert literature has appeared in peer-reviewed publications.

The IPCC has produced a series of assess-ment reports, special reports, technicalpapers and methodologies that havebecome standard works of reference for climate change policymakers, experts, andstudents. The Panel is organized into threeWorking Groups: Working Group I focuseson the science of the climate system;Working Group II on impacts, vulnerabilityand adaptation; and Working Group III onmitigation, a term used to describe human

interventions to reduce greenhouse gasemissions and to enhance “sinks” (forests,oceans and other natural systems that canabsorb carbon dioxide from the atmosphereand store it).

The IPCC’s First Assessment Report wascompleted in 1990 and helped to inspire theintergovernmental talks that led to the 1992United Nations Framework Convention onClimate Change. Its Second AssessmentReport was published in 1996 and played arole in the Kyoto Protocol negotiations. The 2001 Third Assessment Report concen-trated on new findings since 1995 and paidspecial attention to what is known about climate change at the regional level.

About the IPCC

3

Intr

oduc

tion

Introduction

Human activities such as industry and agriculture are emitting carbon dioxide,methane and other greenhouse gases thatchange the way the atmosphere absorbsand re-emits energy. According to currentprojections, higher atmospheric concen-trations of these gases will cause the average global temperature to rise by 1.4 to5.8°C by the year 2100. This warming wouldbe much larger and much more rapid thanany temperature change experienced overat least the last 10,000 years. It would havesignificant impacts on human society andthe natural environment.

Climate change will affect our future ability tosatisfy human needs, in both positive andnegative ways. It will alter agricultural con-ditions; local and regional trends indroughts, floods, and storms; stresses onbuildings and other long-standing infra-structure; health risks; and much more.Many environmental changes that are con-sistent with global warming can already bedetected today.

Some degree of climate change is nowinevitable due to past emissions. One essen-tial strategy for responding to this will beadaptation, which involves taking action to

help communities and ecosystems copewith changing climate conditions.

The second strategy, known as mitigation, isbased on action to limit net emissions ofgreenhouse gases – defined as emissionsminus removals by sinks (such as forests).Limiting emissions will slow and eventuallyreverse the rise in atmospheric concentrationsof greenhouse gases. (Because greenhousegases remain in the atmosphere for decadesor longer, atmospheric levels respond onlygradually to lower emissions.) In this way,mitigation can minimize climate change andits expected negative impacts.

The 185 member governments of the UNClimate Change Convention have agreedthat their objective is to stabilize atmos-pheric concentrations of greenhouse gasesat safe levels. How can this goal best beachieved? What are the most promisingpolicies and technologies? What are theircosts and benefits? What are the barriers toadopting them? And how can action on climate change be made mutually supportivewith sustainable development? This bookletwill explore the IPCC’s answers to thesequestions.

4

Climate change is a global, complex, andlong-term problem (up to several centuries)that is still not fully understood.

Climate change involves complex interac-tions amongst climatic, environmental, eco-nomic, political, institutional, social andtechnological processes. While the IPCCreports reflect a broad scientific consensuson key points such as the reality of therisks involved, they also identify manyuncertainties. Some of these relate to thecomplexity of natural systems, others tothe fact that future human actions affectingclimate change are as yet unknown. Forexample, the type, magnitude, timing and costof mitigation depend on what is feasible –given differing national circumstances, socio-economic conditions and technologies – andon what emissions target has been agreed.The end result is that governments musttake decisions on climate change undercircumstances characterised by uncertaintyand risk.

Climate change is intimately linked to broader developmentissues.Climate change mitigation is not a stand-alone problem: It will both affect and beaffected by socio-economic policies and bychoices involving development, sustain-ability, and equity. Policies to limit net emis-sions can best promote sustainable development if they are consistent withbroader societal objectives. Some mitigation

actions can even promote benefits farbeyond immediate climate concerns – suchas reducing health problems, increasinglocal employment, minimizing air pollution,protecting and enhancing forests andwatersheds, minimizing certain subsidiesand taxes, and accelerating the develop-ment and diffusion of energy-efficient technologies. Similarly, development choicesthat promote sustainability may result inlower emissions.

Equity concerns arise within andbetween countries and genera-tions.Equity issues are shaped by the unequal distribution of resources – technological,natural and financial – between countriesand regions and between present and futuregenerations. They reflect the ability of somecountries (and generations) to reduce emis-sions more or less expensively than otherscan. Inequities are likely to be created orworsened by the impacts of climate changeand of climate changes policies. Concernabout equity led governments to incorporatethe principle of “common but differentiatedresponsibilities” into the Climate ChangeConvention and to assign developed countries – the major emitters to date –responsibility for taking the lead on reducingemissions; developing countries have noquantitative emissions commitments butare expected to pursue development pathsleading to lower emissions.

What is the mitigation challenge?

5

Climate-friendly energy sourcesare the key to cutting emissions.Since fossil fuels are the primary source ofgreenhouse emissions, changing the wayenergy is produced and consumed willprove central to reducing emissions. Mostavailable energy strategies involve movingaway from fossil fuels and exploiting zero-

or low-carbon sources. The extent to whichthe global energy mix evolves towards suchsources will determine whether atmos-pheric concentrations of greenhouse gasesare stabilized or reduced – and at what leveland cost. Currently, most investment inenergy production still goes towards discovering and developing more fossil fuelresources.

Wha

t is

the

miti

gatio

n ch

alle

nge?

6

Technologies and practicesMany low-emissions technologiesare available now – but they arenot being fully exploited.Global emissions could be reduced belowcurrent levels within a few decades usingtechnologies that are already available orbeing tested. These existing technologiesmight even suffice to stabilize atmosphericconcentrations of carbon dioxide (CO2) overthe next 100 years at levels well belowtwice pre-industrial levels (that is, wellbelow 550 parts per million, compared totoday’s 365). This would require transferringthese technologies to countries and regionsthat currently lack them. In addition, manybarriers to fully exploiting low-emissionstechnologies will have to be overcome.

All economic sectors have seen afaster-than-expected developmentof climate-friendly technologiesover the past decade.While it is essential that all sectors exploitnew these technologies, two sectors ofparticular importance will be illustratedbelow. The first is energy and industry,which includes energy production plus energy use in transport, industry and

buildings. Many technologies and practicesinvolving conservation, increased fuel efficiency and alternative fuels are availablefor reducing energy-related emissions. The second key sector is agriculture andforestry. Here the main potential is for storing carbon in sinks and reducing emissions of methane and nitrous oxidethrough improved land management.

All sectors can pursue energyconservation and efficiencyimprovements.Hundreds of technologies and practicesexist for converting fossil fuels into energymore efficiently, thus reducing greenhousegas emissions from households, infrastruc-ture, transport, and industry. For example,combined-cycle gas turbines – in whichthe heat from the burning fuel drives steamturbines while the thermal expansion of theexhaust gases drives gas turbines – mayboost the efficiency of power generation by70%; in the longer term, new technologiescould double the efficiency of power plants.Meanwhile, fuel cells and other advancedautomotive technologies can reduce emis-sions from transport (see Figure 1).

7

Figure 1. Greenhouse gas emissions from advanced automotive technologies and alternativefuels.

0 50 100 150 200 250 300 350

gasoline

gasoline direct injection

propane

CNG

diesel direct injection

20% biodiesel

hybrid (gasoline)

electric vehicle (US mix)

fuel cell (gasoline)

hybrid (CNG)

fuel cell (methanol)

fuel cell (hydrogen fromnatural gas)

electric vehicle (Calif.mix)

fuel cell (solar)

technologies/fuel types

equivalent grams per km

Note: The various greenhouse gases are translated into “CO2 equivalents” that are then added up toproduce a single figure.

Tech

nolo

gies

and

pra

ctic

es

8

Industry’s main short-term optionis to enhance energy efficiency.Industry accounts for over 40% of globalcarbon dioxide emissions, and its energyefficiency varies widely from country tocountry. Short-term improvements maycome from combined heat and power co-generation, other uses of waste-heat,improved energy management, and innova-tions in manufacturing processes. Improvingmaterial efficiency through better productdesign, recycling, and material substitutioncan also reduce emissions. Energy effi-ciency improvements will remain importantfor industry over the longer term as well.

There are many options formoving to cleaner energysources.One of the sources promising fewer emis-sions per unit of energy is natural gas,which, though a fossil fuel, releases lessCO2 than coal or oil. Various forms of renew-able energy can also cut emissions. Theseinclude biomass sources, such as fuel-wood, alcohol fermented from sugar, com-bustible oils extracted from soy beans, andmethane gas emitted by waste dumps.These sources will contribute to emissionsreductions if they are sustainably produced,for example through regular replanting.Where suitable land and water is available,crops grown as biomass fuels can supple-ment naturally existing biomass sources.

Other low- and zero-emissions renewablesinclude hydroelectricity, solar photovoltaics,wind energy and hydrogen fuel cells. Whilelarge-scale hydropower could make a significant contribution to reducing emissions,its use may be limited by concerns about itsimpacts on human settlements and riversystems. The use of non-hydro renewablescontinues to grow as their costs decline,although their contribution to global energysupplies is currently still below 2%.

Nuclear energy also emits virtually nogreenhouse gases. However, it faces pub-lic concerns over safety, the transport anddisposal of radioactive wastes, andweapons proliferation.

Meanwhile, new technologies have becomeavailable that can capture carbon dioxideemitted by fossil-fuel power plants before itreaches the atmosphere. This could offer acost-competitive “clean fossil” energy alter-native to renewables. The captured carbondioxide would be stored underground, inempty oil or gas reservoirs, undergroundwater reservoirs, unused coal beds or in thedeep ocean. Some such applications arealready in operation. However, moreresearch is needed on reducing the costsand assessing the possible risks and envi-ronmental impacts.

Enhancing carbon sinks can par-tially offset fossil fuel emissions.As trees grow, they store carbon, thus keep-ing it out of the atmosphere (see Figure 2).

9

Tech

nolo

gies

and

pra

ctic

es

Sinks can therefore buy time for developinglow-emitting technologies. This can beachieved by:

1. conserving existing carbon sinks, for example by slowing or halting deforestation;

2. expanding the size of carbon sinks, forexample by planting trees or enhancingthe ability of soil to retain carbon; and

3. substituting sustainably-produced biological products for fossil fuels andfossil-fuel-based products, for exampleby using biomass fuels instead of coal oroil for energy, or wood instead of steelfor construction.If properly managed,forest and soil sinks may provide social,economic and environmental benefitsbeyond reducing atmospheric carbondioxide. Healthy forests that absorb CO2can also conserve nature, prevent ero-sion, and create rural employment. Ifpoorly managed, forests and soils cancease storing CO2, lose biodiversity,pollute groundwater and disrupt localcommunities.

Even if the amount of carbon stored in trees,vegetation and soils increases, thereremains a risk that CO2 will be released inthe future if the underlying ecosystem islater disturbed by fire, land clearance orother natural or human-induced changes.Appropriate, long-term land management inareas where carbon is stored is thereforeessential.

Conserving threatened forests may not offset emissions if it simply displaces treecutting or clearing to other areas. To be sustainable, a strategy for enhancing sinksmust address the broader socio-economiccauses of deforestation and other activitiesthat destroy carbon sinks.

Improved agricultural manage-ment can boost carbon storage. Carbon stored in agricultural soils can oftenbe preserved or enhanced through no-tillage or low-tillage techniques, whichslow the rate at which organic soil matterdecomposes. Changing how a parcel ofland is used, for example from cropland tograssland, to better suit its soil character-istics, can also contribute. The introductionof nitrogen-fixing legumes in grazing landfavours carbon storage. Reducing erosionthrough terracing, windbreaks, and residuemanagement can further prevent losses ofcarbon (as well as nitrogen). However, thenet effect of soil erosion on carbon storageis still uncertain, because the carbon ineroded soil may simply be deposited in soilelsewhere and become at least partially stabilized.

In rice fields, methane emissions can besuppressed to some extent through tillagepractices, water management, and croprotation. In general, using nitrogen fertilizersmore efficiently can reduce emissions ofnitrous oxide, which is a powerful green-house gas.

10

Figure 2. Carbon stocks and flows.

Different ecosystems, their components, and human activities. The carbon stocks associated with the different ecosystems are stored in aboveground and belowground biomass, dead organic matter, and soils.Carbon is withdrawn from the atmosphere through photosynthesis (vertical down arrow), and returned byoxidation processes that include plant respiration, decomposition, and combustion (vertical up arrow). Carbonis also transferred within ecosystems and to other locations (horizontal arrows). Both natural processesand human activities affect carbon flows. Mitigation activities directed at one ecosystem component generally have additional effects influencing carbon accumulation in, or loss from, other components.

Note: GtC = Gigatonnes of Carbon; 1 G = 1,000,000,000 tonnes.

Behavioural and economicchanges can support technologi-cal solutions.Climate-friendly technologies are essentialfor reducing emissions, but education, training, public awareness,and institutionalchanges can also contribute. Studies suggest that current incentive systems –based on laws, norms, taxes and other regulatory or market signals that motivateindividuals or organisations to act in a

particular manner – do not discourage, andmay even promote, resource-intensive production and consumption patterns. Newincentives could help reverse this trendand promote climate-friendly changes inlifestyles, consumption patterns and socialorganization. Such changes could include co-owning or renting equipment, shifting to public transport or cycling, reducing transport needs by increasing urban densityand making dietary changes.

11

Cost

s an

d be

nefit

s

Costs and benefits

Mitigation policies can haveboth costs and benefits.The costs of cutting emissions are likely tobe relatively certain, immediate, and borneby an identifiable group. The benefits ofavoided climate change, however, will bespread out over a longer period and may bedifficult to put a price tag on. Many of thoseset to benefit are future generations andindustries that do not yet exist. In additionto these direct costs and benefits, the fullequation must consider the indirect effectsof emissions reduction policies. These“ancillary” effects are defined as the costsand benefits of a policy over and beyondavoided climate change. Many of theseeffects, such as improved air quality andreduced traffic congestion, involve imme-diate benefits.

The costs of climate protectiondepend on the assumptionsmade.Mitigation costs are hotly debated by economists and depend to a great degree oncertain assumptions (see Figure 3):

• the definition of the baseline, that is, thegreenhouse gas emissions that wouldoccur in the absence of emissions policies. The baseline helps determinehow expensive emissions cuts mightbe. It is based on assumptions aboutfuture population trends, economicgrowth, and technological change.

• the discount rate, a measure that economists use to compare future costsand benefits to current costs and bene-fits. A high discount rate reduces thecurrent importance of future costs andbenefits.

• the flexibility of government regulations.The costs of cutting emissions are ofteninfluenced by the regulations adopted bynational governments to address climate change. The more flexibilityallowed by the regulations, the lower theoverall costs to the economy of achievinga given reduction.

• the ancillary costs and benefits of emis-sion reduction policies. Climate changepolicies may have a number of indirectside effects – both positive and negative– on air pollution, transportation, agri-culture, land-use practices, employ-ment, and fuel security. Including theseimpacts in the cost equation can lead tohigher or lower mitigation costs.

• the availability of “no regret options”,which reduce greenhouse gas emis-sions while generating direct or indirect(ancillary) benefits large enough to off-set their costs. In some calculationmethods, “no regret options” are left out.Such zero-cost options may, of course,not be sufficient by themselves toachieve an emissions target and willneed to be supplemented by other meas-ures. In addition, there may be social,economic and other barriers to theiradoption.

12

Figure 3. A typical cost curve showing costs increasing with the level of greenhouse gas reduction.

Marginal cost of abatement

(US$/tC)

Abatement ofGHG emissions

B0

A

Note: From A to B, marginal abatement costs are negative, representing no-regrets solutions. From B onwards, marginal costs are positive.

Internationally traded emissionsallowances could lower costs.Under an international system of tradableemissions allowances – such as the systemestablished under the Kyoto Protocol – eachcountry may emit a certain quantity ofgreenhouse gases each year. Countries thatcan reduce their emissions cheaply may selltheir excess allowances to countries for

which domestic action is more expensive. Inthis way, emissions will tend to be cut whereit is least expensive to do so, lowering theoverall cost. The more countries in the sys-tem, the lower costs are likely to be. In gen-eral, economists estimate that implementingthe Kyoto Protocol would reduce the pro-jected gross domestic product of the OECD(developed) countries by 0.2 – 2%. However,an emissions trading system would lower

13

Cost

s an

d be

nefit

sthis loss to an estimated 0.1 - 1% of futureGDP. Taking into account real-world trans-action costs would increase estimated GDPlosses; taking into account sinks, reductionsin non-C02 greenhouse emissions, ancil-lary benefits and other factors would furtherreduce losses.

Developed country mitigationpolicies could affect developingcountry economies.Because the global economy is so inter-linked, actions by developed countries toreduce greenhouse gas emissions haveimplications for developing countries knownas “spill-over effects”. Such effects gener-ally lead to increased emissions in devel-oping countries, compensating for part ofthe decline in developed countries. Currentestimates are that full-scale implementationof the Kyoto Protocol may cause 5 - 20% ofthe emissions cut in developed countries to“leak” into developing countries.

For example, emissions cuts in developedcountries could lower oil demand and thusinternational oil prices. Those countries nottrying to reduce their greenhouse emis-sions could take advantage of the reducedprice and import more oil, boosting pro-duction and thereby emitting more CO2 thanthey would have otherwise. As a result, oil-importing countries may benefit economically while oil exporters see lowerrevenues.

Another example involves decisions to relocate carbon-intensive industries.Studies suggest that companies mayrespond to emissions controls in developedcountries by moving some facilities to countries without such controls. Such relocation would benefit developing countries economically at the expense ofdeveloped countries. Still another examplemight be a decline in developing countryexports if emissions controls slow economicgrowth in developed countries. Positiveexamples of spill-over exist as well; onewould be the international spread of envi-ronmentally sound technologies in responseto pressures to reduce emissions.

Action to reduce energy emissions can have social andeconomic implications.Production and employment in the coal andoil industries would decline. The natural gasindustry may or may not benefit over the next20 years, depending on local availability, thepotential for gas to replace coal in powergeneration, and other factors. The renew-able energy sector should gain larger markets, but much depends on technologicaldevelopments; in addition, the sector’sprospects vary from region to region. Marketgains for renewables could encourage moreresearch and development as well as investment, leading to lower costs and evenlarger markets. Meanwhile, developing

14

country economies could benefit fromopportunities to “leapfrog” to moreadvanced energy technologies. These coun-tries could skip some of the steps taken byindustrialized countries in their march toadvanced technologies. Technology trans-fer could present opportunities for buildingup domestic expertise and institutions.

The effects on industry are likelyto be mixed.Some industries and technologies producemore value per unit of fossil fuel than do oth-ers, so they are less vulnerable to changingfuel prices; the service sector is an impor-tant example. Similarly, some sectors will bebetter able to adapt their production tech-niques to achieve lower emissions than oth-ers will, and some will find it easier to passon any higher costs to their customers.

Firms will respond to mitigation policies byconserving energy, paying the costs of

domestic controls, or shifting production toforeign countries, either as foreign directinvestment or joint ventures. These actionswill often create ancillary benefits, includ-ing reduced local air pollution, increasedscientific and technological knowledgeabout climate-friendly products andprocesses, and technology transfer todeveloping regions.

Mitigation policies can improveland-use practices.Land-based mitigation activities such asenhancing carbon sinks and producing bio-fuels can have a large effect on land use. Ifadopted on a large scale, they could pro-mote biodiversity conservation, ruralemployment and watershed protection, thuscontributing to sustainable development.Such benefits would be best encouraged byinvolving local communities and industriesin designing and implementing these activities.

15

Barriers to action

There are many barriers to thediffusion of climate-friendlytechnologies.Despite the availability of effective tech-nologies at relatively low costs, efforts tocontrol emissions are not very far advanced.Why is this so? The IPCC concludes that awide range of barriers – technical, eco-nomic, political, cultural, social, behaviour-al and institutional – is obstructing oppor-tunities for reducing emissions.

Institutional barriers exist tosome degree in all countries.Many countries have limited human andinstitutional capacity for implementing andmonitoring mitigation measures. This con-strains and slows down the process ofadopting more efficient technologies toreplace those currently in use. The lack ofeffective regulatory agencies is a furtherconstraint. Many countries have excellentconstitutional and legal provisions for envi-ronmental protection but they are notenforced. A further problem is limited orlacking information; businesses and con-sumers cannot make good decisions aboutwhich technologies to use unless they pos-sess the appropriate information.

Cultural barriers include currentlifestyles, behaviours, and con-sumption patterns.Social conditions can affect consumptionthrough, for example, the association of

certain objects with status and class. Thechoice for more sustainable consumptionpatterns depends not only on the matchbetween those patterns and the perceivedneeds of individuals, but also on the extentto which other consumption options areknown and available.

Economic barriers send unhelpful signals to producers and consumers. Unstable macroeconomic conditionsincrease general investment risks and candiscourage the early adoption of environ-mentally sound technologies, which oftenhave high up-front costs. Certain taxes, fos-sil fuel subsidies, trade barriers and otherpolicy interventions also slow the diffusionof these technologies. Trade barriers mayfavour inefficient technologies or preventaccess to efficient foreign technologies.

Technological barriers can existin the early stages of a technology’s introduction.New technologies may require infrastruc-ture that is not initially available. For exam-ple, the attractiveness of vehicles usingcompressed natural gas depends on theavailability of convenient refuelling sites. Atthe same time, the development of a fuel dis-tribution infrastructure depends on therebeing enough demand.

Bar

rier

s to

act

ion

16

Climate-friendly policies and measuresMany different policies and measures can help to overcomebarriers.Policies and measures can be crafted toinfluence a broad range of economic activ-ities or just one specific sector. Any list ofpossible options would likely include:

• taxes on emissions, carbon, or energy; • subsidies for climate-friendly activities;• deposit-refund systems for appliances,

batteries and other commodities;• voluntary agreements, notably between

governments and the private sector;• emissions trading regimes;• regulations (such as energy-efficiency

standards for buildings);• minimum performance standards for

technologies;• bans on high-emitting products; and• direct government investment in energy-

efficient technologies.

Policies and measures should be selected only after rigorous evaluation.Key criteria to consider include:• Environmental effectiveness. How wellwill the policy achieve its goal of reducingemissions? How reliably will it achieve thatgoal? Will its effectiveness erode over time?Will it create continual incentives to improveproducts or processes in ways that reduce

emissions? Will the policy have wider environmental effects, such as improvedlocal air quality?• Cost-effectiveness. Will the policyachieve its environmental goal at the lowestcost, taking into account transaction, infor-mation, and enforcement costs? What addi-tional benefits will the policy or measurehave? • Equity considerations. How will thecosts of achieving the environmental goal bedistributed across groups within society,now and in the future? How will the policyaffect inflation, competitiveness, employ-ment and trade?• Administrative and political feasibility.Will the policy or measure actually be imple-mented? Is it politically acceptable? Whatare the administrative requirements? Couldthe policy be enforced? How will it interactwith other government objectives (such asmeeting fiscal targets)? Will it contribute tochanging attitudes and increasing aware-ness of climate change?

Because the importance of these criteriawill differ according to time and place, mostgovernments will limit net emissions througha portfolio of policy instruments, rather thana single policy. In this way, policymakers cancombine the strengths of various policyinstruments while compensating for theirweaknesses, thus improving overall effec-tiveness and efficiency.

17

Clim

ate-

frie

ndly

pol

icie

s an

d m

easu

resCountries may benefit from

coordinating their policies andmeasures.Coordinating action among countries andsectors could help address concerns aboutcompetitiveness and potential conflicts withinternational trade rules. It could alsoreduce costs. Some options are:

• the Kyoto Protocol mechanisms, name-ly joint implementation (JI), the cleandevelopment mechanism (CDM) andinternational emissions trading;

• an international tax on emissions, car-bon, or energy;

• internationally coordinated productstandards; and

• international voluntary agreements.

Non-climate policies can alsoaffect greenhouse gas emis-sions.Examples include trade liberalization, priceand subsidy reforms and the opening of ener-gy markets. Such macroeconomic policiescan create favourable conditions for pro-moting climate-friendly investments.

18

Towards sustainable developmentEnvironment and developmentissues are strongly interlinked.Climate change, biodiversity, desertifica-tion, freshwater supplies, forests and pover-ty are linked through a complex set of physical, chemical, and biological processes(see Figure 4). Climate change, for example,alters the global hydrological cycle, affectsthe functioning of ecological systems, andaccelerates land degradation and deserti-fication. These negative impacts can rein-force each other and seriously threatenland productivity, food, freshwater supplies,and biological diversity. Policies addressingclimate change can thus ameliorate otherproblems. They can also involve trade-offs,however. For example, depending on how it ismanaged, large-scale tree planting aimed atsequestering carbon could negatively affectlocal biodiversity and local developmentopportunities.

Treaties on environment and sustainable development sharecommon goals and means.The international community is addressingenvironment and sustainable developmentthrough a range of binding and non-bindingagreements. These agreements – the deser-tification, biodiversity, climate change andozone treaties, for example – tend to inter-act at many levels. They also share manycommon features, requiring their members

to:

• build governmental and civil institutionsto implement internationally agreedactions;

• formulate strategies and action plans asa framework for country-level imple-mentation;

• collect data and report on their obligations;and

• strengthen the capacity of both humanresources and institutions.

Coordinating the implementation of theseagreements at the local, national and inter-national levels can reinforce their effec-tiveness and avoid duplication of effort.

National policies can ensure thatclimate change and sustainabledevelopment goals are mutuallyreinforcing.Policies for limiting emissions can be moreeffective when they take developmentissues into account. Conversely, non-climate policies can produce climate benefits.

Recognizing the potential for synergiesbetween climate and development canlower the political and institutional barriers for climate-specific measures.Many synergies can be found in actionsrelated to industry, transportation, agricul-ture, forestry, and human settlements.

19

Greater impactLess impactEqual impact

Tow

ards

sus

tain

able

dev

elop

men

t

Figure 4. Linkages among environmental issues.

20

For example, decentralized developmentpatterns based on a stronger role for small-and medium-sized cities can slow the ruralexodus and reduce transport needs. Theycan also encourage solar energy, small-scale hydropower and other technologiesthat enable communities to tap their naturalresources sustainably. Similarly, adoptingenvironmentally sound technologies for bothenergy production and energy consumptioncan reduce public investments, improveexport competitiveness, and enlarge ener-gy reserves, while avoiding greenhouse gasemissions.

In Africa, a growing number of communitiesare turning to agroforestry, where trees areplanted to delineate plots of land while fur-ther fixing nitrogen in the soil. The trees alsosequester carbon, prevent soil erosion, sup-ply firewood and animal fodder, and provideincome. Organic farming can also reducenet greenhouse gas emissions while improv-ing soil fertility through the addition oforganic matter. The damage and diseasescaused by insects can virtually be eliminat-ed through the technique of “growing in cor-ridors”, which also avoids the costs of fer-tilisers and pesticides.

Synergies can be capturedthrough institutional changes andstakeholder involvement.In many countries, each environmentalissue is dealt with by a different governmentagency. This can sometimes lead to dupli-cation, poor information flow, inefficientresource allocation, and a general lack ofcoordination. Improving the links amongstnational agencies and institutions can great-ly strengthen the sustainable developmentagenda. Even greater synergies could beachieved if agencies with global and localagendas do business together.

21

Nex

t ste

ps

Next steps

The IPCC’s Third Assessment Report hasreconfirmed that the threat of climatechange is real and that there is enough evi-dence to warrant immediate action. It is timenow to act on the basis of key decisions –decisions about how to adapt to expectedimpacts, how to limit and reduce green-house gas emissions, which priority actionsto start with, and how to ensure their effec-tiveness and minimize their costs.

Fortunately, opportunities abound for reduc-ing net emissions. They all involve eitherreducing human-induced emissions or cap-turing carbon dioxide from the atmosphereand sequestering it. They include invest-ments in low-emissions technologies, insti-tutional and regulatory changes that dis-courage emissions, and a wide range oftechnical practices and social changes.The costs of minimizing climate change canbe kept relatively low by timing emissionscuts to coincide with new investments inenergy production, energy use and infra-structure. There are many barriers to action,but policymakers can now accelerate theirefforts to overcome them. The active par-ticipation of civil society is also vital.

Much of the debate about climate changerevolves around the broader issues of devel-opment and the unequal distribution ofwealth amongst the world’s nations. By

implementing climate policies in the contextof sustainable development, and taking cli-mate change into account in all aspects ofnational policy-making, governments canminimize climate change while meetingother social goals.

Although great advances have been madein understanding climate change and miti-gation opportunities, research on resolvingthe remaining uncertainties must continueat full speed. There is a growing consensuson the availability of low-emissions tech-nologies, and more research is needed intothe barriers impeding their up-take, policiesand measures for overcoming them, andtheir costs and benefits. However, whilesuch studies promise to strengthen mitiga-tion efforts over the longer term, the IPCCfindings demonstrate the importance ofstarting to reduce emissions now.

22

Glossary of terms

Adaptation Adjusting natural or human systems to cope with actual or expected climate change and its impacts.

Alternative energy Energy derived from non-fossil fuel sources.

Anthropogenic Greenhouse gas emissions associated with human activities such as

emissions burning fossil fuels or cutting down trees.

Ancillary effects Side effects of policies to reduce net greenhouse gas emissions, such asreductions in air pollutants associated with fossil fuels or socio-econom-ic impacts on employment or agricultural efficiency.

Annex B Developed countries included in Annex B of the Kyoto Protocol, which

countries/Parties assigns quantitative emissions targets for the period 2008-2012.

Barrier Any obstacle to the diffusion of cost-effective mitigation technologies orpractices, whether institutional, social, economic, political, cultural or technological.

Baseline The greenhouse gas emissions level that would occur in the absence of cli-mate change interventions; used as a basis for analysing the effectivenessof mitigation policies.

Biofuel Fuel produced from dry organic matter or combustible oils from plants, suchas alcohol from fermented sugar, black liquor from the paper manufactur-ing process, wood, and soybean oil.

Biological options There are three: conserving an existing carbon pool, and thereby prevent-ing emissions into the atmosphere; sequestrating more CO2 from theatmosphere by increasing the size of existing carbon pools; and substitut-ing biological products for fossil fuels or for energy-intensive products,thereby reducing CO2 emissions.

Biomass The total mass of living organisms in a given area or volume; biomass canbe used as a sustainable source of fuel with low or zero net emissions.

Emissions tax A levy imposed by a government on each unit of CO2 equivalent emissionsfrom a source subject to the tax; can be imposed as a carbon tax to reducecarbon dioxide emissions from fossil fuels.

23

Glo

ssar

y of

term

sEmissions trading A market-based approach to achieving environmental objectives thatallows countries or companies that reduce greenhouse gas emissions belowtheir target to sell their excess emissions credits or allowances to thosethat find it more difficult or expensive to meet their own targets.

Fossil fuels Carbon-based fuels from fossil carbon deposits, including coal, oil, and nat-ural gas.

Leakage Occurs when emissions reductions in developed countries are partly off-set by increases above baseline levels in developing countries, due to relo-cation of energy-intensive production, increased consumption of fossil fuelswhen decreased developed country demand lowers international oil prices,or changes in incomes and thus in energy demand because of better termsof trade, or when sink activities such as tree planting on one parcel of landencourage emitting activities elsewhere.

Mitigation Action to reduce sources or enhance sinks of greenhouse gases.

No regrets policy Policies that would generate net social benefits whether or not there is cli-mate change; for example, the value of reduced energy costs or local pol-lution may exceed the costs of cutting the associated emissions.

Policies and measures Action by government to promote emissions reductions by businesses, indi-viduals, and other groupings; measures include technologies, processes,and practices; policies include carbon or other energy taxes and stan-dardized fuel-efficiency standards for automobiles.

Renewables Energy sources that, within a timeframe that is brief relative to the earth’snatural cycles, are sustainable; examples are non-carbon technologies suchas solar energy, hydropower, and wind, as well as carbon-neutral tech-nologies such as biomass.

Sequestration The process of removing and storing carbon dioxide from the atmospherethrough, for example, land-use change, afforestation, reforestation, orenhancements of carbon in agricultural soils.

Spill-over effect The economic effects of domestic or sectoral mitigation measures on othercountries or sectors, which can be positive or negative and include effectson trade, carbon leakage, and the transfer and diffusion of environmental-ly sound technologies.

24

Stakeholders People or entities with interests that would be affected by a particular actionor policy.

Sequestration The process of removing and storing carbon dioxide from the atmospherethrough, for example, land-use change, afforestation, reforestation, orenhancements of carbon in agricultural soils.

Spill-over effect The economic effects of domestic or sectoral mitigation measures on othercountries or sectors, which can be positive or negative and include effectson trade, carbon leakage, and the transfer and diffusion of environmental-ly sound technologies.

Stakeholders People or entities with interests that would be affected by a particular actionor policy.

Subsidy A direct payment from the government to an entity, or a tax reduction to thatentity, for implementing a practice the government wishes to encourage;greenhouse gas emissions can be discouraged by reducing fossil-fuel sub-sidies or granting subsidies for insulating buildings or planting trees.

Technology transfer An exchange of knowledge, money, or goods that promotes the spread oftechnologies for adapting to or mitigating climate change; the term gener-ally refers to the diffusion of technologies and technological co-operationacross and within countries.

Voluntary agreement An agreement between government and business, or a unilateral private-sector commitment that is acknowledged by the government, aimed atachieving environmental objectives or improving environmental perform-ance.

Voluntary measures Measures to reduce greenhouse gas emissions that are adopted by firmsor other actors in the absence of government mandates; they can involvemaking climate-friendly products or processes more readily available orencouraging consumers to incorporate environmental values in their mar-ket choices.

What do we know

about reducing

greenhouse

gas emissions?

A simplified guide to the IPCC’s

“Climate Change 2001: Mitigation”

Information Unit for ConventionsUnited Nations Environment

ProgrammeCH-1219 Geneva, Switzerland

Tel: +41 (22) 917 82 44 / 917 81 96Fax: + 41 (22) 797 34 64

Web: www.unep.ch/conventions