Japan's emissions of greenhouse gases decreased marginally in fiscal 1997, according to an Environment Agency report presented Friday to the Cabinet.

The report shows Japan released nearly 1.38 billion tons (calibrated in units of carbon dioxide) of the six heat-trapping gases to be reduced under the United Nations Framework Convention on Climate Change.

This represents a 0.2 percent drop from the previous year but is still about 8.5 percent higher than 1990 levels, the base year for reductions of three of the gases.

Of total greenhouse gas emissions, 1.23 billion tons, or nearly 90 percent, came from carbon dioxide -- down 0.4 percent from the year before, but still a 9.4 percent increase over 1990 levels.

Environmental Agency officials attributed the slight drop in heat-trapping gas emissions to the poor economic performance and unusually warm weather that led to a decrease in the use of heaters.

Gases to be reduced under the international agreement include carbon dioxide, methane and nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride.

Overall, industry accounted for 40 percent of carbon dioxide emissions, transportation for nearly 21 percent and private homes for more than 12 percent.

Of the major sectors, only the transportation sector showed an increase in carbon dioxide emissions.

Under the Kyoto Protocol put forth at the third convention of the parties under the international agreement, Japan has agreed to reduce its greenhouse gas emissions by 6 percent of 1990 emission levels in the period from 2008 to 2012.

The Environment Agency also reported to the same Cabinet-level gathering on its efforts to tackle global warming in 1998 and overall progress to address the issue as well as announcing its global warming research plan for fiscal 1999.