The projected climate changes in the twenty-first century are so large that, even at the low end of the range of possibilities, impacts will require costly adaptations, and in some cases our capacity to adapt will not be enough to avoid serious damage to individuals and society. It will therefore be necessary to reduce climate change by reducing net greenhouse gas emissions to the atmosphere. In the language used by the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change (UNFCCC), this is called ‘Mitigation’.
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Changes in lifestyle and behavior patterns can contribute to climate change mitigation across all sectors. Management practices can also have a positive role.
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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.
- 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.
- 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.
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The economic potential in energy sector is predominantly located in energy intensive industries. Full use of available mitigation options is not being made in either industrialized or developing nations.
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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 feed stocks for energy use.
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Forest related mitigation practices 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.
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Post consumer waste is a small contributor to global GHG emissions [mainly from land-fill methane and the burning of solid waste], but the waste sector can positively contribute to GHG mitigation at low cost and promote sustainable development.
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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.
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To this we should add carbon capture and sequestration associated with natural or artificial bio fuel production as a means of taking carbon out of the atmosphere as will be needed in the case of overshoot scenarios.