Energy and climate change

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In its Fourth Assessment Report,1 the Intergovernmental Panel on Climate Change (IPCC)2 concluded, "Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse-gas concentrations". The language "very likely" has been upgraded from the "likely" that was referred to six years earlier in the Third Assessment Report, thus confirming the broad acceptance by scientists of the link between greenhouse-gas emissions and global climate change. Energy production and use has various environmental implications: since energy represents about 65% of global anthropogenic greenhouse-gas emissions, reducing emissions must necessarily start with actions geared to reduce emissions from fuel combustion.

Greenhouse gases and global warming

The increased concentrations of key greenhouse gases (GHG) are a direct consequence of human activities. Since anthropogenic greenhouse gases accumulate in the atmosphere, they produce net warming by strengthening the natural "greenhouse effect".

1. IPCC Fourth Assessment Report - Climate Change 2007, available at http://www.ipcc.ch. In the summary for Policymakers, the following terms have been used to indicate the assessed likelihood, using expert judgement, of an outcome or a result: Virtually certain > 99% probability of occurrence, Extremely likely > 95%, Very likely > 90%, Likely > 66%, More likely than not > 50%, Unlikely < 33%, Very unlikely < 10%, Extremely unlikely < 5%.

2. The IPCC was created in 1988 by the World Meteorological Or ganisation and the United Nations Environment Programme to assess scientific, technical and socio-economic information relevant for the understanding of climate change, its potential impacts, and options for adaptation and mitigation.

Carbon dioxide (CO2) has been increasing over the past century compared to the rather steady level of the pre-industrial era (about 280 parts per million in volume, or ppmv). The 2005 concentration of CO2 (379 ppmv) was about 35% higher than a century and a half ago, with the fastest growth occurring in the last ten years (1.9 ppmv/year in the period 1995-2005). Comparable growth has also occurred in levels of methane (CH4) and nitrous oxide (N2O).

Some impacts of the increased greenhouse-gas concentrations may be slow to become apparent since stability is an inherent characteristic of the interacting climate, ecological and socio-economic systems. Even after stabilisation of the atmospheric concentration of CO2, anthropogenic warming and sea level rise would continue for centuries due to the time scales associated with climate processes and feedbacks. Some changes in the climate system would be effectively irreversible.

Given the long lifetime of CO2 in the atmosphere, stabilising concentrations of greenhouse gases at any level would require large reductions of global CO2 emissions from current levels. The lower the chosen level for stabilisation, the sooner the decline in global CO2 emissions would need to begin, or the deeper the emission reduction would need to be on the longer term.

The 1992 UN Framework Convention on Climate Change (UNFCCC)3 creates a structure for intergovernmental efforts to tackle the challenge posed by climate change. The Convention's ultimate objective is to stabilise GHG concentrations in the atmosphere at a level that would prevent dangerous anthropogenic

3. See http://unfccc.int.

interference with the climate system. This would require significant reductions in global greenhouse-gas emissions.

Energy use and greenhouse gases

Among the many human activities that produce greenhouse gases the use of energy represents by far the largest source of emissions. As seen in Figure 1, energy accounts for over 80% of the anthropogenic greenhouse gases in Annex I countries, with emissions resulting from the production, transformation, handling and consumption of all kinds of energy commodities. Smaller shares correspond to agriculture, producing mainly CH4 and N2O from domestic livestock and rice cultivation, and to industrial processes not related to energy, producing mainly fluorinated gases and N2O.

Figure 1. Shares of anthropogenic greenhouse-gas emissions in Annex I countries, 2006*

Industrial processes 7%

Industrial processes 7%

* Based on Annex I data for 2006; without Land Use, Land-Use Change and Forestry, and with Solvent Use included in Industrial Processes.

Source: UNFCCC.

Key point: Accounting for the largest share of global greenhouse-gas emissions, energy emissions are predominantly CO2.

The energy sector is dominated by the direct combustion of fuels,4 a process leading to large emissions of CO2. A by-product of fuel combustion, CO2 results from the oxidation of carbon in fuels (in perfect combustion conditions, the total carbon content of fuels would be converted to CO2).

4. Energy includes emissions from "fuel combustion" (the large majority) and "fugitive emissions", which are intentional or unintentional releases of gases resulting from production, processes, transmission, storage and use of fuels (e.g. CH4 emissions from coal mining or oil and gas systems).

CO2 from energy represents about 80% of the anthropogenic greenhouse-gas emissions for the Annex I countries5 and about 60% of global emissions. This percentage varies greatly by country, due to diverse national energy structures.

Worldwide economic stability and development require energy. Global total primary energy supply (TPES) doubled between 1971 and 2007, mainly relying on fossil fuels (Figure 2). However, with the current economic crisis, early indicators suggest that growth in TPES slowed in 2008 and may have declined in 2009.

Figure 2. World primary energy supply*

Gt of oil equivalent 14

12 10 8

Figure 2. World primary energy supply*

Gt of oil equivalent 14

12 10 8

18%

82%

14%

86%

I Fossil üNon fossil

2007

1971

I Fossil üNon fossil

2007

* World primary energy supply includes international bunkers.

Key point: Fossil fuels still account for most of the world energy supply.

Despite the growth of non-fossil energy (such as nuclear and hydropower) considered as non-emitting,6 fossil fuels have maintained their shares of the world energy supply relatively unchanged over the course of the past 35 years. In 2007, fossil sources accounted for 82% of the global TPES.

Still dependent upon fossil fuels, the growing world energy demand clearly plays a key role in the

5. Based on Annex I countries. The Annex I Parties to the UNFCCC are: Australia, Austria, Belarus, Belgium, Bulgaria, Canada, Croatia, Czech Republic, Denmark, Estonia, European Economic Community, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Latvia, Lichtenstein, Lithuania, Luxembourg, Monaco, the Netherlands, New Zealand, Norway, Poland, Portugal, Romania, Russia, the Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom and United States.

6. Excluding the life cycle of all non-emitting sources and excluding combustion of biomass (considered as non-emitting CO2, based on the assumption that the released carbon will be reabsorbed by biomass re-growth, under balanced conditions).

observed upward trends in CO2 emissions (Figure 3). Since the Industrial Revolution, annual CO2 emissions from fuel combustion dramatically increased from near zero to 29 Gt CO2 in 2007.

Figure 3. Trend in CO2 emissions from fossil fuel combustion

Gt CO2

Figure 3. Trend in CO2 emissions from fossil fuel combustion

1990 2006

Source: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, Tenn., United States.

Key point: Since 1870, CO2 emissions from fuel combustion have risen exponentially.

The World Energy Outlook:7 projects that world energy supply will rise by 40% between 2007 and 2030. With fossil fuels remaining at around 80% of TPES, CO2 emissions from fuel combustion are consequently expected to continue their growth unabated, reaching 40.2 Gt CO2 by 2030. Such an emission-growth trend would be in line with the worst-case scenario presented in the IPCC report,8 which projects a world average temperature change between 2.4 and 6.4°C by 2100.

The link between climate change and energy is a part of the larger challenge of sustainable development. The socio-economic and technological characteristics of development paths will strongly affect emissions, the rate and magnitude of climate change, climate change impacts, the capability to adapt and the capacity to mitigate the emissions themselves.

7. Unless otherwise specified, projections from the World Energy Outlook refer to the Reference Scenario from the IEA information paper "How the Energy Sector can Deliver on a Climate Agreement in Copenhagen", a special early excerpt of the World Energy Outlook 2009 for the Bangkok UNFCCC meeting.

8. IPCC Fourth Assessment Report - Climate Change 2007.

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