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Global average atmospheric carbon dioxide rose from 280 ppm at the start of the industrial revolution to 381 ppm in 2006. The present concentration is the highest during the last 650,000 years and probably during the last 20 million years. The growth rate of global average atmospheric carbon dioxide for 2000–2006 was 1.93 ppm per year, which is the highest since the beginning of continuous monitoring in 1959 and a significant increase over growth rates in earlier decades: the average growth rates for the 1980s and the 1990s were 1.58 and 1.49 ppm each year, respectively.
Image credit: British Antarctic Survey.