Dr Jiang spoke yesterday at a Victoria University climate change conference, having been brought to Australia by the government's Climate Commission as the first of six international guests to report on steps overseas to reduce emissions. His visit came as miner Rio Tinto intensified its opposition to Australia's carbon pricing scheme, urging Prime Minister Julia Gillard to start again on carbon policy.

Rio Tinto's Australian general manager David Peever said the government had not adapted to international changes since the failed Copenhagen climate talks of 2009, saying ''There must be, and is, a better way for Australia to make its contribution.''

The government will introduce legislation on Tuesday for a fixed carbon tax to start next year, evolving into an emissions trading scheme in 2015.

Dr Jiang - from the National Development and Reform Commission's Energy Research Institute and a lead author with the Intergovernmental Panel on Climate Change - gave evidence that China's emissions were increasing at an extraordinary rate, and that Beijing's five-year economic plan included a framework aimed at slowing and eventually halting the growth. China's emissions have nearly tripled since 2000 as the developing country experienced an unprecedented period of economic growth. Some estimates suggest China may emit up to 30-40 per cent more carbon dioxide than the US, the world's second largest emitter.

In response it was piloting emissions trading schemes in six provinces and cities. Each area would test a different design, varying in the size of the emissions limit imposed on business and the way in which emissions levels were monitored and verified. Dr Jiang said it was unlikely China would move from pilot programs to a full national trading scheme by 2015 as some analysts had speculated. He said China's emissions level could peak by 2025 - earlier than government modelling suggestions that it would continue to rise until 2030.