«Over the past 30 years,» Zerefos said, «human beings have increased carbon dioxide emissions by 15 percent with every form of combustion. But there is great inequality between states. «In the USA, Canada and Australia, emissions per head are 2.5 times greater than in Europe.» Scientists have estimated emissions at 6 to 7 billion tons a year, he said. Carbon dioxide, Zerefos continued, contributes to the greenhouse effect by 60 percent. In the post-Kyoto era, industrialized countries are obliged to reduce their CO2 emissions by 5.2 percent by 2008-2012, as measured against 1990 levels. The EU has bound itself to an 8 percent reduction. Greece successfully pushed to be allowed an increase in emissions in the region of 25 percent by 2010-2012, but, according to a report by the National Observatory, will have gone well over target by then. Estimates put emissions increases in this country at 36 to 52 percent by 2012.