Since 1750, the atmospheric concentration of carbon dioxide has increased by about 32% (from about 280 to 376 parts per million in 2003), primarily due to the combustion of fossil fuels and land use changes. Approximately 60% of that increase (60 parts per million) has taken place since 1959.
Data: Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: Synthesis.
Island Press, Washington, DC.