China's emissions of carbon dioxide need to peak by 2020 if the world is to meet its 2050 targets aimed at curbing climate change, the head of the International Energy Agency said. IEA director Nobuo Tanaka, in Beijing to launch a new report into clean energy technologies, told a briefing that China needed to do more if the global community was to stand any chance of achieving a 50% cut in greenhouse gases by 2050 � a target regarded by the Intergovernmental Panel on Climate Change as the minimum required to prevent catastrophic warming. "If we have to reduce emissions by 50% globally, what is the least cost to make this happen? China could peak in 2030 or 2035, but the global cost will be much more," he said. Chinese academics in attendance responded critically to the remarks, saying the 2020 peak target � together with a projected 36% cut in coal consumption by 2050 � would force China to sacrifice economic growth. Shortly before global climate change talks in the Danish capital of Copenhagen last year, China pledged to reduce energy intensity � the amount of carbon dioxide produced per unit of GDP � by 40-45% by 2020. However, it has balked at the notion of making mandatory greenhouse cuts as part of any new global accord, saying that industrialised nations have been responsible for the bulk of historical emissions and should bear most of the burden for reducing them � a principle enshrined in the Kyoto Protocol. The IEA report said that the installation of carbon capture and storage (CCS) technology could contribute as much as 18% to China's required emission cuts, but progress on the technology has so far been disappointing.