Greenhouse gas emissions either can continue to increase, can be held steady at a particular level, or can be reduced to a lower level. Some consequences of the presence of greenhouse gases in the atmosphere may be unavoidable. Adaptation to climate change may require providing alternate sources of water and improving flood-control provisions such as levees.
The two main opportunities for reducing greenhouse gases are (1) reducing the amount of coal used to generate electricity and (2) reducing the amount of petroleum burned in the transportation system.
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Emissions from coal burning can be reduced by reducing electricity demand through conservation practices.
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Emissions from coal can be reduced in the short term by using more efficient IGCC power plants.
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Emissions from coal can be captured and stored in depleted oil fields, coal mines, or the oceans.
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Non polluting alternatives to coal-fired electricity generation include hydroelectric, wind, solar, and nuclear power.
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Although the sources of biomass fuels such as ethanol, cellulosic ethanol, and biodiesel remove carbon dioxide from the air as they grow, that carbon dioxide is released to the atmosphere when the fuel is burned. Under some, but not all, applications, the overall emissions from biomass fuels may be less when considering the overall life cycle of the fuel.
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Diesel engines are more efficient and produce fewer greenhouse gas emissions than conventional spark-ignited internal combustion engines.
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Emissions from cars can be reduced by more efficient designs, including gas–electric hybrids, plug-in hybrids, and hydrogen combustion or hydrogen fuel cell engines. The carbon dioxide reductions will be significant only if the source of electricity used emits a minimal amount of carbon dioxide.