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The president of the United States discussed carbon emissions during the 2009 election campaign. Cap and trade, also called emission trading or emissions trading, is a system for trading emission credits (crédits de pollution) between polluters and non-polluters. A central authority sets a limit, or cap, on total emissions. Companies that need to increase their emission allowance must buy credits from those that pollute less.1
Carbon is used elliptically to mean carbon dioxide. Carbon dioxide capture and storage (CCS) is a process consisting of the separation of carbon dioxide (CO2) from industrial and energy-related sources, its transport to a storage location and its long-term isolation from the atmosphere.2
The latest trend is to be certified as having a net zero carbon footprint (empreinte carbone nette zéro).3 The CSA online climate change glossary defines carbon footprint as the total greenhouse gas (GHG) emissions and reductions for an organization over a specific time period.4
When coal, oil and gas are burned, they produce carbon dioxide. Recent studies blame the cumulative emission of greenhouse gases, in particular CO2, for rising global temperatures. As a result, the word carbon has come to mean all greenhouse gases that contribute to global warming. In order to reflect the fact that there are other types of greenhouse gases, some people use the expression climate neutral (climat neutre) rather than carbon neutral (neutre en carbone or carboneutre). However, the more popular carbon neutral was selected as the 2006 word of the year by the New Oxford American Dictionary.6
Organizations that are serious about social responsibility can become certified as having a net zero carbon footprint by means of an environmental assessment of their operations to reduce the GHGs that cause climate change. Some organizations purchase carbon offsets by investing in renewable energy, such as solar and wind energy, or in tree-planting projects, because it is virtually impossible to be totally carbon neutral.
Carbon sequestration (séquestration de carbone)7 requires the capture and removal of atmospheric CO2. Increasing the land area under cultivation may result in greater CO2 absorption (plants act as carbon sinks).8 Agricultural sinks were discussed in the Kyoto Protocol on climate change.
Geoengineering is considered a last-ditch effort to save us from global warming. It may be loosely defined as "any engineering activity that is concerned with large-scale alterations to the Earth or its atmosphere."10 Two grand schemes are being studied. The first approach is to pull CO2 from the air (carbon sequestration). With the second, some percentage of incoming sunlight would be blocked to reduce temperatures. One suggestion is to do this by "injecting massive amounts of sulfur into the upper atmosphere"11 like a huge volcano eruption, a solution which raises many issues, including ocean acidification. Other proposals include sunshades, space mirrors and spraying seawater into the troposphere on a long-term basis.
Judith Layzer at MIT thinks that carbon-removal schemes might hold some promise. These ideas include enhancements to natural biological processes that remove carbon from the air, or the development of technological substitutes such as "artificial trees" that could have the same effect.12
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