"With eight percent growth, emissions will increase by 74 percent," said Emmanuel Guerin, a climate analyst at France's Institute for Sustainable Development and International Relations (IDDRI).
"China, having emitted 7.2 gigatonnes of carbon dioxide equivalent in 2005, will spew out 12.6 gigatonnes in 2020," he was quoted news agency over telephone from the Danish capital.
Another study by a panel of European experts says China's total emissions could be even higher.
"Chinese carbon emissions will double by 2020," a member of that panel said on condition of anonymity.
Commission's environment spokeswoman, Barbara Helfferich said, "Since the reduction goal is linked to GDP, with expected high economic growth in the next 10 years, Chinese emissions will most likely continue to grow very rapidly."
Higher GDP growth rates would require higher CO2 intensity improvements in order to meet an emissions trajectory that limits climate change to two degrees Celsius," she added.