Japan's Prime Minister, Shinzo Abe, has said the world should halve emissions of greenhouse gases by 2050.
Japan has become the most energy efficient country in the world
It is the first time Japan has set a firm target to replace the present Kyoto protocol, which expires in 2012.
The plan is believed to be less demanding than other proposals from European countries such as the UK.
But Mr Abe said it was important to come up with a scheme flexible enough to win over those countries which are among the world's biggest polluters.
"We must create a new framework which moves beyond the Kyoto Protocol, in which the entire world will participate in emissions reduction," Mr Abe said in a speech in Tokyo.
He made it clear that his country wanted to take a leading role in efforts to reduce greenhouse gases.
But Mr Abe said he believed those efforts would fail unless the countries which are among the biggest polluters, China, India and the United States, could be persuaded to take part.
He said that any new post-Kyoto framework to try to reduce CO2 emissions must be flexible enough to be acceptable to every country in the world.
Different countries might need to take different kinds of measures, he said, adding that Japan would help by sharing the knowledge that has allowed it to become the most energy efficient country in the world.
"Japan, as a country with advanced technologies, can make a significant contribution," he said.
Mr Abe said Japan would work with the World Bank and the United Nations, to find extra money to help fund assistance for poorer countries who find it difficult to improve energy efficiency, he said.
According to the BBC correspondent in Tokyo, Chris Hogg, Japan is still struggling to meet its current obligations to reduce greenhouse gases by 6% by 2012.
To some extent that is because Japanese firms were already very energy efficient when the targets were set, our correspondent says.
Mr Abe said he would work harder to make sure Japanese public bodies and big companies cut emissions further, and added that he would encourage ordinary Japanese people to do their part too.
The Kyoto Protocol, which was signed in Japan in 1997, requires the 35 nations that signed up to the pact to cut their greenhouse gas emissions by 5% from 1990 levels, by 2012.