Climate change in Japan and Toyota hybrid electric vehicles were named to have the highest fuel efficiency and lowest emissions. The fuel economy and emissions decrease is due to the advanced technology in hybrid systems, biofuels, use of lighter weight material and better engineering. As a signatory of the Kyoto Protocol, and host of the 1997 conference which created it, Japan is under treaty obligations to reduce its carbon dioxide emissions and to take other steps related to curbing climate change. The Cool Biz campaign introduced under former Prime Minister Junichiro Koizumi was targeted at reducing energy use through the reduction of air conditioning
Geography of Japan 3 July 2018, Japan's government pledged to increase renewable energy sources from 15% to 22-24% including wind and solar by 2030. Nuclear energy will provide 20% of the country's energy needs as an emissions-free energy source. This will help Japan meet climate change commitments. Most regions of Japan, such as much of Honshu, Shikoku and Kyushu, belong to the temperate zone with humid subtropical climate (Köppen climate classification "Cfa") characterized by four distinct seasons. However, its climate varies from cool humid continental climate (Köppen climate classification "Dfb") in the north such as northern Hokkaido, to warm tropical rainforest climate (Köppen