| Greenhouse
gas emission trends |
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Global
greenhouse gas (GHG) emissions have grown since
pre-industrial times, with an increase of 70% between
1970 and 2004 (high agreement, much evidence) . |
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With
current climate change mitigation policies and related
sustainable development practices, global GHG
emissions will continue to grow over the next few decades (high
agreement, much evidence). |
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Baseline
emissions scenarios published since SRES, are comparable
in range to those presented in the IPCC Special Report on
Emission Scenarios (SRES) (25- 135 GtCO2-eq/yr in 2100,
see Figure SPM.4). (high agreement, much evidence) |
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| Mitigation
in the short and medium term (until 2030) |
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Both
bottom-up and top-down studies indicate that there is substantial
economic potential for the mitigation of global GHG
emissions
over the coming decades, that could offset the projected
growth of global emissions or reduce emissions below
current levels (high agreement, much evidence). Key mitigation
technologies and practices by sector
| Sector |
Key
mitigation technologies and practices currently
commercially available |
Key
mitigation technologies and practices projected
to be commercialized before 2030. |
| Energy
Supply |
Improved
supply and distribution efficiency; fuel
switching from coal to gas; nuclear power;
renewable heat and power (hydropower, solar,
wind, geothermal and bioenergy); combined heat
and power; early applications of CCS (e.g.
storage of removed CO2 from natural gas) |
Carbon
Capture and Storage (CCS) for gas, biomass and
coal-fired electricity generating facilities;
advanced nuclear power; advanced renewable
energy, including tidal and waves energy,
concentrating solar, and solar PV. |
| Transport |
More
fuel efficient vehicles; hybrid vehicles; cleaner
diesel vehicles; biofuels; modal shifts from road
transport to rail and public transport systems;
non-motorised transport (cycling, walking);
land-use and transport planning |
Second
generation biofuels; higher efficiency aircraft;
advanced electric and hybrid vehicles with more
powerful and reliable batteries |
| Buildings |
Efficient
lighting and daylighting; more efficient
electrical appliances and heating and cooling
devices; improved cook stoves, improved
insulation ; passive and active solar design for
heating and cooling; alternative refrigeration
fluids, recovery and recycle of fluorinated gases
|
Integrated
design of commercial buildings including
technologies, such as intelligent meters that
provide feedback and control; solar PV integrated
in buildings |
| Industry |
More
efficient end-use electrical equipment; heat and
power recovery; material recycling and
substitution; control of non-CO2 gas emissions;
and a wide array of process-specific technologies |
Advanced
energy efficiency; CCS for cement, ammonia, and
iron manufacture; inert electrodes for aluminium
manufacture |
| Agriculture |
Improved
crop and grazing land management to increase soil
carbon storage; restoration of cultivated peaty
soils and degraded lands; improved rice
cultivation techniques and livestock and manure
management to reduce CH4 emissions; improved
nitrogen fertilizer application techniques to
reduce N2O emissions; dedicated energy crops to
replace fossil fuel use; improved energy
efficiency |
Improvements
of crops yields |
| Forestry/forests
|
Afforestation;
reforestation; forest management; reduced
deforestation; harvested wood product management;
use of forestry products for bioenergy to replace
fossil fuel use |
Tree
species improvement to increase biomass
productivity and carbon sequestration. Improved
remote sensing technologies for analysis of
vegetation/ soil carbon sequestration potential
and mapping land use change |
| Waste |
Landfill
methane recovery; waste incineration with energy
recovery; composting of organic waste; controlled
waste water treatment; recycling and waste
minimization |
Biocovers
and biofilters to optimize CH4 oxidation |
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| Estimated
sectoral economic potential for global mitigation
for different regions as a function of carbon
price in 2030 from bottom-up studies, compared to
the respective baselines assumed in the sector
assessments. |
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In 2030
macro-economic costs for multi-gas mitigation, consistent
with emissions trajectories towards stabilization between 445
and 710 ppm CO2-eq, are estimated at between a 3% decrease of
global GDP and
a small increase, compared to the baseline. However,
regional costs may differ significantly from global
averages(high agreement,
medium evidence) |
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Changes in lifestyle and
behaviour patterns can contribute to climate
change mitigation across all sectors. Management
practices can
also have a positive role. (high agreement, medium
evidence) |
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While
studies use different methodologies, in all analyzed
world regions near-term health
co-benefits from reduced air pollution as a result of actions to
reduce GHG emissions can be substantial and may offset a
substantial fraction of mitigation costs (high agreement,
much evidence). |
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Literature
since TAR confirms that there may be effects from Annex I
countries （気候変動枠組条約の付属書 I に記載される国々。2000までに温室効果ガスの排出量を1990年レベルに減少させることが義務付けられている。）action on the global
economy and global emissions, although the scale of
carbon leakage remains uncertain (high agreement, medium
evidence). |
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New
energy infrastructure investments in developing
countries, upgrades of energy infrastructure in
industrialized countries, and policies that promote
energy security, can, in many cases, create opportunities
to achieve GHG emission reductions compared to baseline
scenarios. Additional co-benefits are country-specific
but often include air pollution abatement, balance of
trade improvement, provision of modern energy services to
rural areas and employment (high agreement, much
evidence). |
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There
are multiple mitigation options in the transport sector ,
but their effect may be counteracted by growth in the
sector. Mitigation options are faced with many barriers,
such as consumer preferences and lack of policy
frameworks (medium agreement, medium evidence). |
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Energy
efficiency options for new and existing buildings could
considerably reduce CO2 emissions with net economic
benefit. Many barriers exist against tapping this
potential, but there are also large co-benefits (high
agreement, much evidence). |
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The
economic potential in the industrial sector is
predominantly located in energy intensive industries.
Full use of available mitigation options is not being
made in either industrialized or developing nations (high
agreement, much evidence). |
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Agricultural
practices collectively can make a significant
contribution at low cost to increasing soil carbon sinks,
to GHG emission reductions, and by contributing biomass
feedstocks for energy use (medium agreement, medium
evidence). |
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Forest-related
mitigation activities can considerably reduce emissions
from sources and increase CO2 removals by sinks at low
costs, and can be designed to create synergies with
adaptation and sustainable development (high agreement,
much evidence) . |
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Post-consumer
waste is a small contributor to global GHG emissions
(<5%), but the waste sector can positively contribute
to GHG mitigation at low cost and promote sustainable
development (high agreement, much evidence). |
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Geo-engineering
options, such as ocean fertilization to remove CO2
directly from the atmosphere, or blocking sunlight by
bringing material into the upper atmosphere, remain
largely speculative and unproven, and with the risk of
unknown side-effects. Reliable cost estimates for these
options have not been published (medium agreement,
limited evidence) |
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| Mitigation
in the long term (after 2030) |
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In
order to stabilize the concentration of GHGs in the
atmosphere, emissions would need to peak and decline
thereafter. The lower the stabilization level, the more
quickly this peak and decline would need to occur.
Mitigation efforts over the next two to three decades
will have a large impact on opportunities to achieve
lower stabilization levels (high agreement, much
evidence). 
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Stabilization
scenario categories as reported in Figure SPM.7 (coloured
bands) and their relationship to equilibrium global mean
temperature change above pre-industrial, using (i) “best
estimate”
climate sensitivity of 3°C (black
line in middle of shaded area), (ii) upper bound of
likely range of climate sensitivity of 4.5°C (red line at top of
shaded area) (iii) lower bound of likely range of climate
sensitivity of 2°C (blue line at bottom of
shaded area). Coloured shading shows the concentration
bands for stabilization of greenhouse gases in the
atmosphere corresponding to the stabilization scenario
categories I to VI as indicated in Figure SPM.7. |
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The
range of stabilization levels assessed can be achieved by
deployment of a portfolio of technologies that are
currently available and those that are expected to be
commercialised in coming decades. This assumes that
appropriate and effective incentives are in place for
development, acquisition, deployment and diffusion of
technologies and for addressing related barriers (high
agreement, much evidence). |
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In
2050 global average macro-economic costs for multi-gas
mitigation towards stabilization between 710 and 445 ppm
CO2-eq, are between a 1% gain to a 5.5% decrease of
global GDP. For specific countries and sectors, costs
vary considerably from the global average. (high
agreement, medium evidence). |
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Decision-making
about the appropriate level of global mitigation over
time involves an iterative risk management process that
includes mitigation and adaptation, taking into account
actual and avoided climate change damages, co-benefits,
sustainability, equity, and attitudes to risk. Choices
about the scale and timing of GHG mitigation involve
balancing the economic costs of more rapid emission
reductions now against the corresponding medium-term and
long-term climate risks of delay [high agreement, much
evidence]. |
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| Policies,
measures and instruments to mitigate climate change |
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A
wide variety of national policies and instruments are
available to governments to create the incentives for
mitigation action. Their applicability depends on
national circumstances and an understanding of their
interactions, but experience from implementation in
various countries and sectors shows there are advantages
and disadvantages for any given instrument (high
agreement, much evidence). |
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Policies
that provide a real or implicit price of carbon could
create incentives for producers and consumers to
significantly invest in low-GHG products, technologies
and processes. Such policies could include economic
instruments, government funding and regulation (high
agreement, much evidence) |
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Selected
sectoral policies, measures and instruments that have
shown to be environmentally effective in the respective
sector in at least a number of national cases.
| Sector |
Policies,
measures and instruments shown to be
environmentally effective |
Key
constraints or opportunities |
| Energy supply |
Reduction
of fossil fuel subsidies |
Resistance by
vested interests may make them difficult to
implement |
| Taxes
or carbon charges on fossil fuels |
| Feed-in
tariffs for renewable energy technologies |
May be appropriate
to create markets for low emissions technologies |
| Renewable
energy obligations |
| Producer
subsidies |
| Transport |
Mandatory
fuel economy, biofuel blending and CO2 standards
for road transport |
Partial
coverage of vehicle fleet may limit effectiveness |
| Taxes
on vehicle purchase, registration, use and motor
fuels, road and parking pricing |
Effectiveness
may drop with higher incomes |
| Influence
mobility needs through land use regulations, and
infrastructure planning |
Particularly
appropriate for countries that are building up
their transportation systems |
| Investment
in attractive public transport facilities and
non-motorised forms of transport |
| Buildings |
Appliance
standards and labelling |
Periodic
revision of standards needed |
| Building
codes and certification |
Attractive
for new buildings. Enforcement can be difficult |
| Demand-side
management programmes |
Need
for regulations so that utilities may profit |
| Public
sector leadership programmes, including
procurement |
Government
purchasing can expand demand for energy-efficient
products |
| Incentives
for energy service companies (ESCOs) |
Success
factor: Access to third party financing |
| Industry |
Provision
of benchmark information |
May be appropriate
to stimulate technology uptake.
Stability of national policy important in view of
international competitiveness |
| Performance
standards |
| Subsidies,
tax credits |
| Tradable
permits |
Predictable
allocation mechanisms and stable price signals
important for investments |
| Voluntary
agreements |
Success
factors include: clear targets, a baseline
scenario, third party involvement in design and
review and formal provisions of monitoring, close
cooperation between government and industry. |
| Agriculture |
Financial
incentives and regulations for improved land
management, maintaining soil carbon content,
efficient use of fertilizers and irrigation |
May
encourage synergy with sustainable development
and with reducing vulnerability to climate
change, thereby overcoming barriers to
implementation |
| Forestry/Forests |
Financial
incentives (national and international) to
increase forest area, to reduce deforestation,
and to maintain and manage forests |
Constraints
include lack of investment capital and land
tenure issues. Can help poverty alleviation. |
| Land
use regulation and enforcement |
| Waste management |
Financial
incentives for improved waste and wastewater
management |
May
stimulate technology diffusion |
| Renewable
energy incentives or obligations |
Local
availability of low-cost fuel |
| Waste
management regulations |
Most
effectively applied at national level with
enforcement strategies |
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Government
support through financial contributions, tax credits,
standard setting and market creation is important for
effective technology development, innovation and
deployment. Transfer of technology to developing
countries depends on enabling conditions and financing
(high agreement, much evidence). |
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Notable
achievements of the UNFCCC and its Kyoto protocol are the
establishment of a global response to the climate
problem, stimulation of an array of national policies,
the creation of an international carbon market and the
establishment of new institutional mechanisms that may
provide the foundation for future mitigation efforts
(high agreement, much evidence). |
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The
literature identifies many options for achieving
reductions of global GHG emissions at the international
level through cooperation. It also suggests that
successful agreements are environmentally effective,
cost-effective, incorporate distributional considerations
and equity, and are institutionally feasible (high
agreement, much evidence). |
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| Sustainable
development and climate change mitigation |
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Making
development more sustainable by changing development
paths can make a major contribution to climate change
mitigation, but implementation may require resources to
overcome multiple barriers. There is a growing
understanding of the possibilities to choose and
implement mitigation options in several sectors to
realize synergies and avoid conflicts with other
dimensions of sustainable development (high agreement,
much evidence). |
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| Gaps
in knowledge |
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There are still
relevant gaps in currently available knowledge regarding
some aspects of mitigation of climate change, especially
in developing countries. Additional research addressing
those gaps would further reduce uncertainties and thus
facilitate decision-making related to mitigation of
climate change. |
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