Using the fiscal 1990 baseline, Japan achieved an 8.2 percent cut in emissions of carbon dioxide and other greenhouse gases from fiscal 2008 to 2012, meeting a 6 percent target under the 1997 Kyoto Protocol on curbing global warming, government sources said Saturday.

The preliminary figure shows Tokyo managed to fulfill its obligation during the first commitment period under the Kyoto pact due to a plunge in emissions in fiscal 2009 caused by a global financial crisis as well as forest absorption and the country's purchase of emissions credits from overseas, the sources said.

Environment Minister Nobuteru Ishihara is set to announce the nation's achievement of the 6 percent cut target at the ongoing U.N. climate talks in Warsaw, they said.

But greenhouse gas emissions in Japan have been rising since the 2011 Fukushima disaster, which left most of Japan's nuclear plants offline and revived thermal power generation.

Tokyo has decided not to join an eight-year second commitment period from 2013 for the Kyoto Protocol, saying the framework lacks effectiveness as major gas-emitting countries such as the United States and China are not part of the reduction efforts.

On Friday, Tokyo set a new target of slashing greenhouse gas emissions by 3.8 percent in fiscal 2020 from fiscal 2005 levels, assuming nuclear power plants in the country remain offline.

But the revised goal has immediately drawn criticism as it represents an rise of about 3 percent in emissions from the Kyoto Protocol base year of fiscal 1990.