China’s carbon emissions will start falling by 2050, its top climate change policymaker said, the first time the world’s largest emitter has given such a time-frame.

Whether China will agree to some kind of cap on its emissions is a critical question ahead of global climate change talks in December in Copenhagen. Beijing argues, as do most developing countries, that developed nations should take responsibility for cutting emissions first, since global warming originated with their industrialisation.

The comments by Su Wei, director-general of the climate change department at China’s planning body – the National Development and Reform Commission – signal not only increasing flexibility in Beijing’s approach but also continued unreadiness to accept an emissions ceiling in the short term.

“China’s emissions will not continue to rise beyond 2050,” Mr Su told the Financial Times.

China and India have been resisting pressure from developed nations to agree to a target of reducing emissions by an overall average of 50 per cent by 2050. Mr Su restated Beijing’s view that as China still needs to grow its economy to help its people escape poverty, it is too early to discuss emissions caps.

But he indicated an openness to compromise. “China will not continue growing emissions without limit or insist that all nations must have the same per-capita emissions. If we did that, this earth would be ruined.” His estimate of the peak of China’s emissions is in line with the more pessimistic forecasts issued by climate change experts. The UK’s Tyndall Centre for Climate Change Research recently said China’s energy-related CO2 output would peak in 2030 at 57 per cent above current levels.

The Chinese Academy of Sciences has said that with major technological support from developed nations, China could see its emissions peak between 2030 and 2040. Other Chinese experts say carbon output will keep rising until 2050 unless radical controls are adopted.