China's greenhouse gas emissions are expected to rise higher than expected, even though the country is on course to meet or even surpass pledges made at the Cancun, Mexico, climate summit last year, a new study indicates.

Due to a faster-than-anticipated economic growth rate -- which Beijing said is expected to exceed 9 percent growth this year -- China's overall emissions are projected to be about 1 gigaton more in 2020 than previously calculated, claims the Climate Action Tracker report.

The report by Ecofys, Climate Analytics and the Potsdam Institute for Climate Impact Research was released at the United Nations-led climate talks this week in Panama, the final meeting before the Durban summit next month.

China has been successful in rapidly reducing its energy intensity and in introducing renewable energy and other non?fossil energy sources, the report said, noting that China's energy consumption per gross domestic product had decreased by more than 19 percent from 2006-10, just less than the government's target of 20 percent.

Under its latest five-year plan, Beijing is aiming for a further reduction of energy per gross domestic product of 16 percent from 2011-15. China also plans to increase the share of non?fossil fuels in primary energy consumption from 8.3 percent in 2010 to 11.4 percent in 2015.

"It is becoming so much clearer that while China has achieved a lot, it still has a way to go as its GDP continues to rise fast," said Niklas Hohne of Ecofys.

A separate study, "Carbonizing Dragon: China's fast growing CO2 emissions revisited," published in the journal Environmental Science and Technology says that the construction of buildings, power plants and infrastructure in China to accommodate its booming economy is leading to a rise in carbon emissions.

Researchers determined that China's emissions nearly tripled from 1992-2007, increasing about 4 billion tons, with 70 percent of that growth occurring from 2002-07.

"The recent rise in emissions is completely due to the massive structural change of China's economy," said the study's lead author Jan Minx from the Potsdam Institute for Climate Impact Research and the Technical University of Berlin.

When calculated at the point of consumption, cement accounts for 46 percent of the country's emissions and iron and steel 20 percent in total.

"Emissions grow faster and faster, because CO2 intensive sectors linked to the building of infrastructure have become more and more dominant," Minx said. "China has developed into a 'carbonizing dragon'."