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Carbon Dioxide Emissions and Concentrations on the Rise as Kyoto Era Fades
According to the latest on-site measurements by the Scripps Institute of Oceanography, global atmospheric carbon dioxide (CO2) concentrations reached 391.3 parts per million (ppm) in 2011, up from 388.56 ppm in 2010 and from 280 ppm from pre-industrial times.1 (See Figure 1.) Carbon dioxide accounts for more than 70 percent of the greenhouse gases (GHGs) in the atmosphere and—thanks to its very long life span—is the most important anthropogenic greenhouse gas responsible for global warming.2
After declining 1.5 percent in 2009, global CO2 emissions jumped 5.8 percent in 2010, an unprecedented increase in the last two decades.3 CO2 levels are now 45 percent above the 1990 level, the reference base year under the United Nations Framework Convention on Climate Change (UNFCCC).4 (See Figure 2.) Levels of methane (CH4) and nitrous oxide (N2O) have also increased significantly, but they account for a smaller share of greenhouse gases in the atmosphere—17 percent and 8.7 percent respectively.5
Deforestation and logging, forest and peat fires, and the decomposition of organic carbon drained in peat soils are estimated at around 14 percent of global CO2 emissions; however, this number is highly uncertain and varies from 15 percent to 30 percent between years.6 Industrial processes, mainly the production of cement, constitute another 5 percent of global CO2 emissions.7
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