In the 1980s the figure was 1.6 ppm, and in the 1990s 1.5 ppm.In the period 2000-2007, however, the concentration jumped to an average 2.0 ppm, with a high of 2.2 last year, according to the Global Carbon Project, based in Australia.The present concentration is the highest during the last 650,000 years and probably during the last 20 million years, said the Global Carbon Project's Pep Canadell,