Prof van Ypersele, who is a member of the UN Climate Panel, says that CO2 is one of the most important greenhouse gases of human-making and is a crucial factor in global warming.
"We can go back 800,000 years in time and analyse air quality because we can analyse air bubbles trapped in ice in Antarctica. In the period before a million years ago we have never measured values above 300 ppm. Now as a result of the burning of fossil fuels this figure has risen to 400 ppm in only a hundred years. We are heading for even higher values."
The member of the UN Climate Panel says action is urgently needed: "If this is repeated we are looking at the melting of the Greenland icecap in 500 to 1000 years. Sea levels would rise by 6 metres. We're playing with fire if we do not act."