毎日新聞 2007/5/5

CO2削減 1トン最大80ドル必要 
 2030年時点 IPCCが試算

 バンコクで開かれていた、地球温暖化対策を話し合う国連の「気候変動に関する政府間パネル(IPOC)第3作業部会(対策)は4日、2100年までに大気中の温室効果ガス濃度を550PPMに抑えるためには、30年までに二酸化炭素(CO2)1トンの削減費用を最大で80米ドル(9600円)まで伸ばすことが必要との
報告書をまとめた。この濃度に保てば地球上の平均温度を90年比2.2〜2.6度の上昇でとどめることができ、費用対効果の高い技術が普及すれば30年の排出量を現在のレベル以下にすることもできるという。

気候変動に関する政府問パネル(lPCC)
 科学、影響、対策の3つの作業部会に分かれ、最新の分析をまとめる国連機関。130カ国以上から約4000人の専門家が参画し、発表済みの成果を評価して確度の高い情報を提供する。温暖化をめぐる各国の政策に影響を及ぼしている。
 最初の報告書は90年で、今回が4回目。第1作業部会(科学)は2月、今世紀末の平均気温が1.1〜6.4度上昇すると予測。
 第2作業部会(影響)は4月、気温上昇が2〜3度を超えれば、世界で経済的損失が生じると指摘した。
IPCC報告
 第一作業部会(科学) 
IPCC報告書案  温暖化 今世紀末時点 最悪6.4度
                (ブログ 
http://www.knak.jp/blog/2007-02-1.htm#ipcc)  
 第二作業部会(影響) 
国連バネルが報告採択 温暖化、全地球に影響
                (ブログ 
http://www.knak.jp/blog/2007-04-1.htm#ipcc-2) 
 第三作業部会(対策) 
CO2削減 1トン最大80ドル必要 
               
 (ブログ http://www.knak.jp/blog/2007-05-1.htm#ipcc-3 

濃度に応じ複数のシナリオ
 IPCCは今回、温室効果ガスの濃度をどのレペルで安定させるかによつて、さまざまなシナリオを描いた。温暖化防止の目標が違えば、CO2排出を減少に転じさせる排出ピーク年や温度上昇幅、コストなどが異なってくる。温度上昇が2〜3度を超えれば温暖化の悪影響が顕顕著になるとの「許容限度」が先月、示されていた。

C02削減量とコスト

温室効果ガス濃度

安定レベル
(ppm)
CO2排出

ピーク年

50年の世界排出量
  (00年比、%)

温度上昇

90年比

CO2 1トン削減費用

30年時点

対GDPコスト(%)

30年まで

50年まで
445〜490 2000〜15  -85 〜 -50 1.4〜1.8    (3未満)  (5.5未満)
490〜535 2000〜20  -60 〜 -30 1.8〜2.2    (3未満)  (5.5未満)
535〜590 2000〜30  -35 〜 + 5 2.2〜2.6 (550ppm) 20〜80ドル  0.6(0.2〜2.5)  1.3(〜4)
590〜710 2000〜60  +10 〜 +60 2.6〜3.4 (650ppm) 0〜30ドル  0.2(0.6〜1.2)  0.5(-1〜2)
710〜855 2000〜80  +25 〜 +85 3.4〜4.3 (750ppm) 0〜20ドル    
855〜1130 2000〜90  +90 〜 +140 4.3〜5.5      

IPCCの報告書などを基に作成。
 温室効果ガスの安定レベルは濃度でC02換算
 対GDPコストは中央値、カッコ内は範囲。気候変化被害のコストは織リ込んでいない。
 1トン削減の費用は、それぞれ550ppm、650ppm、750ppmの場合。空欄は明確な試算がない。


2007/5/4 New York Times

Beating Global Warming Need Not Cost the Earth: U.N.

``It's a great report and it's very strong and it shows that it's
economically and technically feasible to make deep emission reductions sufficient to limit warming to 2 degrees,'' he said. ``It shows that the costs of doing this are quite modest.''

To keep within the 2 degree threshold which scientists say is needed to stave off disastrous changes to the world's climate,
emissions of carbon dioxide need to drop between 50 and 85 percent by 2050, the report said.

In 2030 the costs for limiting greenhouse gases at ''stabilization'' levels of between 445 and 710 ppm (parts per million) CO2-equivalent range from a 3 percent decrease of global GDP to a small increase, it said.

Greenhouse gas concentrations are now at about 430 ppm CO2-equivalent.


IPCC Fourth Assessment Report  The Working Group III  2007/5/4
http://www.ipcc.ch/SPM040507.pdf

Greenhouse gas emission trends
Global greenhouse gas (GHG) emissions have grown since pre-industrial times, with an increase of 70% between 1970 and 2004 (high agreement, much evidence) .
   
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).
   
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)
   
Mitigation in the short and medium term (until 2030)
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
 
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.
 
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)
   
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)
   
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).
   
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).
   
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).
   
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).
   
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).
   
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).
   
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).
   
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) .
   
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).
   
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)
   
Mitigation in the long term (after 2030)
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).

  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 estimateclimate 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.
   
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).
   
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).
   
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].
   
Policies, measures and instruments to mitigate climate change
  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).
   
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)
   
  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
   
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).
   
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).
   
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).
   
Sustainable development and climate change mitigation
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).
   
Gaps in knowledge
  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.