Historical emissions of carbon from fossil fuel (coal, oil, and gas) combustion and land-use change (such as deforestation) have increased over time. The growth rate was nearly three times greater during the 2000s as compared to the 1990s. This figure compares the observed historical (black dots) and projected future SRES (orange dashed lines) and RCP (blue solid lines) carbon emissions from 1970 to 2030. (Data from Boden et al. 2011fdf3a7f6-dead-4249-b0ca-e7b6e2ac6f16 plus preliminary values for 2009 and 2010 based on BP statistics and U.S. Geological Survey cement data).