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Background Information > Fact Sheets

Reducing the Emissions that Cause Climate Change

In the context of climate change, mitigation is a human intervention to reduce the sources or enhance the sinks of greenhouse gases.

United Nations Framework Convention on Climate Change

• Without additional action by governments, emissions of the six main greenhouse gases — carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, PFCs and HFCs — are set to rise dramatically. Between 1970 and 2004, emissions of these gases increased by 70 per cent.
• By adopting stronger climate change policies, governments could slow and reverse these emission trends and ultimately stabilize the level of greenhouse gases in the atmosphere. For example, stabilizing greenhouse gas levels at 445-490 ppm — the most ambitious target that was assessed — would require global CO₂ to peak by 2015 and to fall to 50-85 per cent of 2000 levels by 2050. This could limit global mean temperature increases to 2-2.4°C above pre-industrial levels.
• Stabilizing greenhouse gases levels at 535-590 ppm would require global CO₂ emissions to peak by 2010-2030 and return to -30 per cent to +5 per cent of 2000 levels by around 2050. This could limit the temperature increase to 2.8-3.2°C. If emissions peak later, more warming can be expected. By way of comparison, the 2005 level of greenhouse gases is about 379 ppm.
• Mitigation efforts over the next two to three decades will determine to a large extent the long-term global mean temperature increase and the corresponding climate change impacts that can be avoided. Properly designed climate change policies can be part and parcel of sustainable development and the IPCC’s findings confirm that sustainable development paths can reduce greenhouse gas emissions and reduce vulnerability to climate change.

Reducing Emissions Requires Help from all Sectors of the Economy

• There is no single solution to climate change — The IPCC concludes that no single economically and technologically feasible solution would, on its own, suffice for reducing greenhouse gas emissions from different sectors. At the same time, it is clear is that coordinated action at the international level is needed to harness the full effect of clean technologies and energy efficiency.
• Energy — US$ 20 trillion is expected to be invested in upgrading global energy infrastructure from now until 2030 to meet rising demand, which will grow by about 60 per cent in that time according to the International Energy Agency and the additional cost of altering these investments in order to reduce greenhouse gas emissions is estimated to range from negligible to an increase of 5-10 per cent. The way in which these energy needs are met will determine whether climate change will remain manageable. Mitigation efforts over the next two to three decades will determine to a large extent the long-term global mean temperature increase and the corresponding climate change impacts that can be avoided.
  • The wide deployment of climate-friendly technologies is critical. Existing clean technologies need to be rapidly adopted by the private sector and deployed widely, including through technological cooperation between industrialized and developing countries. Addressing climate change will, however, require continuous improvement through innovation and the development of new technologies.
  • Cleaner technologies and energy efficiency can provide win-win solutions, allowing economic growth and the fight against climate change to proceed hand in hand. With the continued dominant role of fossil fuels in the global energy mix, energy efficiency, cleaner fossil fuel and carbon capture and storage technologies are needed to allow their continued use without jeopardizing climate change objectives.
  • Renewable energy can help. According to UNEP and New Energy Finance, sustainable energy investment has increased markedly over the past couple of years, with wind, solar and biofuels attracting the highest levels of investment. This reflects technology maturity, policy incentives and investor appetite. Investor appetite suggests that existing technology is ready for scale-up and that renewable energy can become a larger part of the energy mix without waiting for further technology development.
  • To fully meet the mitigation challenge across the globe, such a scale-up needs to be promoted and the further diffusion of technologies needs to be supported, including through enhanced cooperation between industrialized and developing countries. For this to happen, governments need to further concretize and support a market-friendly, clear and predictable playing field for private investors.
  • Governments need to promote a range of energy options — These could include encouraging natural gas over more carbon-intensive fossil fuels as well as mature renewable energy technologies such as large hydro, biomass combustion and geothermal. Other renewable sources include solar assisted air conditioning, wave power and nanotechnology solar cells, although they all still require more technological or commercial development. Yet another option could be carbon capture and storage technology, which involves capturing carbon dioxide before it can be emitted into the atmosphere, transporting it to a secure location, and isolating it from the atmosphere, for example by storing it in a geological formation.
• Buildings — Approximately 30 per cent of the projected baseline emissions in the residential and commercial sectors — the highest rate amongst all sectors studied by the IPCC — could be reduced by 2030 with a net economic benefit. Energy consumption and embodied energy in buildings can be cut through greater use of existing technologies such as passive solar design, high-efficiency lighting and appliances, highly efficient ventilation and cooling systems, solar water heaters, insulation, highly-reflective building materials and multiple glazing. Government policies on appliance standards and building energy codes could further provide incentives and information for commercial action in this area.
• Transport — Technologies that could help reduce emissions range from direct injection turbocharged diesels and improved batteries for road vehicles to regenerative breaking and higher efficiency propulsion systems for trains to blended wing bodies and unducted turbofan propulsion systems for airplanes. Biofuels also have the potential to replace a substantial proportion of the petroleum that is currently being used by transport. Providing public transport systems and promoting non-motorised transport can also reduce emissions. Management strategies for reducing traffic congestion and air pollution can also be effective in reducing private-vehicle travel.
• Industry — The greatest potential for reducing industrial emissions is located in the energy-intensive steel, cement, pulp and paper industries and in the control of non-CO₂ gases such as HFC-23 from the manufacturing of HCFC-22, PFCs from aluminumsmelting and semiconductor processing, sulphur hexafluoride from use in electrical switchgear and magnesium processing, and methane and nitrous oxide from the chemical and food industries.
• Agriculture — Sequestering carbon in the soil represents about 89 per cent of the mitigation potential in this area. Other options include improved management of crop and grazing lands (e.g. improved agronomic practices, nutrient use, tillage and residue management), restoration of organic soils that are drained for crop production, and restoration of degraded lands. Lower but still significant reductions are possible with improved water and rice management; set-asides, land use change (e.g. converting cropland to grassland) and agro-forestry; and improved livestock and manure management.
• Forests — Arresting today’s high levels of deforestation and planting new forests could considerably reduce greenhouse gas emissions at low costs. About 65 per cent of the total mitigation potential for forests lies in the tropics and 50 per cent can be achieved by simply avoiding deforestation. In the longer term, the best way to maintain or increase the ability of forests to sequester carbon is through sustainable forest management, which also has many social and environmental benefits. A comprehensive approach to forest management can ensure an annual sustained yield of timber, fibre or energy that is compatible with adapting to climate change, maintaining biodiversity and promoting sustainable development.
• Wastes — Post-consumer waste makes up almost 5 per cent of total global greenhouse gas emissions. Technology can directly reduce emissions by recovering gases emitted from landfills but also through improved landfill practices and engineered wastewater management. Controlled composting of organic waste, state-of-the-art incineration and expanded sanitation coverage can also help avoid generating these gases in the first place. It is estimated that 20-30 per cent of projected emissions from waste for 2030 can be reduced at negative cost and 30-50 per cent at low costs.

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