A U.N. body has estimated that even if carbon dioxide emissions are cut to half what they were in 2000, the average temperature worldwide could still rise by nearly 3 C by 2050. CO2 emissions have rapidly increased since the Industrial Revolution of the late 18th century due to the rising consumption of fossil fuels, including coal, petroleum and natural gas, to provide power for human activities.

In the past 10 years, the density of CO2 in the atmosphere increased by 1.9 parts per million each year. CO2 is a so-called greenhouse gas that acts to trap heat within the Earth's atmosphere.

Should CO2 density continue to increase, temperatures will continue to rise, and the resulting change in the climate will lead to irreparable damage to the Earth, through extreme weather and the extinction of various species of plant and animal life around the world.

Therefore, stabilizing the density of CO2 and other greenhouse gases in the atmosphere was set as the main goal of the United Nations Framework Convention on Climate Change. In its fourth assessment report, compiled last year, the Intergovernmental Panel on Climate Change drew up six scenarios envisioning temperature increases in line with the rise in CO2 density.

According to the report, temperatures will rise by as much as 2.8 C compared with preindustrial times, even if a goal proposed by the Japanese government in 2007 to halve greenhouse gas emissions by 2050 compared to levels at that time is achieved.

The Kyoto Protocol set greenhouse gas emission reduction targets for its signatory countries between 2008 and 2012: a total reduction of 5 percent for industrially advanced nations including a 6 percent reduction for Japan and an 8 percent cut for European Union nations.

Scientists have been further discussing possible levels of CO2 emission reduction at international conferences.

The Japanese government is supposed to compile a report next spring on its assessment of the amount of CO2 emission reduction possible for each region of the world.

However, it is likely that the amount of emission reduction possible will not reach the level needed to have any significant impact on the climate.

Commenting on the issue, former Environment Minister Hiroshi Oki, who chaired the COP3 meeting where the Kyoto Protocol was adopted, said, "It'll be possible to reduce a large amount of CO2 [emissions] if we can adopt a lifestyle featuring solar energy, wind power and other natural energy sources, decreasing the consumption of fossil fuels to close to zero."

(The Yomiuri Shimbun, 13/11/2008)