FACTBOX: Japan's mid-term emission cut scenarios

(Reuters) - Japan's top climate policy advisory panel published on Thursday six scenarios as a basis to decide a national greenhouse gas emissions target to 2020, to be announced by June.

Japan argues that because it is so energy efficient already, it will be more expensive to meet the same emissions-cutting target of other rich countries.

A working group of experts will make a final proposal by early April at the latest.

"We're not recommending any of the six scenarios yet. They are a basis of further discussions," the working group's chairman and former Bank of Japan governor Toshihiko Fukui told a news conference.

While pledging to cut emissions by 60-80 percent from current levels by 2050, Japan has stopped short of a 2020 goal.

Following are the six preliminary scenarios for further discussions, based on an assumption that Japan's real gross domestic product grows by 1.6 percent a year on average by 2020:

1) Under current trends of corporate investment in energy efficiency carbon emissions rise by 6 percent versus 1990. Clean energy sources, excluding nuclear energy, would account for 4 percent of primary energy supply.

2) If the corporate sector voluntarily applies the most advanced, energy efficient technologies, carbon emissions fall by 4-5 percent from 1990. The share of renewable energy sources is 7-8 percent.

3) If Japan matches the investment that the EU will have to make to cut its greenhouse gas emissions by 20 percent by 2020 from 1990 levels, Japan's carbon emissions rise by 0-7 percent

4) If Japan matches the investment all rich countries would make under a joint goal to cut emissions by 25 percent, its emissions would fall by 1-12 percent by 2020.

5) If Japan spends as much as a proportion of gross domestic product as other rich nations to meet a common 25 percent goal, its emissions would fall by 16-17 percent. Renewable energy would reach about 10 percent.

6) If Japan cut its emissions by 25 percent, the same as other rich countries, that would require a jump in the renewable energy share to 13 percent.

(Reporting by Risa Maeda; editing by Gerard Wynn and Guy Dresser)