The Intergovernmental Panel on Climate Change (IPCC) proposes two hypothetical future scenarios. One is Scenario "A1B" based on the assumption that a future world will have more global economic growth (the concentration of carbon dioxide will be 720ppm in 2100). The other is Scenario "B1" based on the assumption that a future world will have global green economy (the concentration of carbon dioxide will be 550ppm in 2100).
Earth Simulator calculations reveal the daily increase in mean temperature in Japan during the period of 2071 to 2100. The temperature will increased by 3.0 °C in Scenario B1 and 4.2 °C in A1B compared to that of 1971 to 2000. Similarly, the daily maximum temperature in Japan will increase by 3.1 °C in B1 and 4.4 °C in A1B. The precipitation in summer in Japan will increase steadily due to global warming (annual average precipitation will increase by 17% in Scenario B1 and by 19% in Scenario A1B during the period of 2071 to 2100 compared to that of 1971 to 2000).
Currently, Japan is a world leader in the development of new climate-friendly technologies. Honda 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 use in government offices.
Japan's capital Tokyo is preparing to force industry to make big cuts in greenhouse gases, taking the lead in a country struggling to meet its Kyoto Protocol obligations. Tokyo's outspoken governor, Shintaro Ishihara, decided to go it alone and create Japan's first emissions cap system, reducing greenhouse gas emission by a total of 25 percent by 2020 from the 2000 level.
On June 25, 2008, the Tokyo Metropolitan Assembly approved a program for the reduction of CO
2 emissions starting in 2010. About 1,300 large offices and factories in Tokyo that consume electric power equivalent to 1,500 kilolitres of crude oil annually must reduce CO
2 emissions by 15–20% of the average volume from the three years before this bylaw. Even with emissions trading or cap-and-trade, if the targeted reduction not is achieved by 2020, a penalty of up to JPY500,000 will be charged. This penalty chargeable regulation is the first in Japan.
Japan created the Kyoto Protocol Target Achievement Plan to lay out the necessary measures required to meet their 6% reduction commitment under the Kyoto Protocol. It was first established as an outcome of the evaluation of the Climate Change Policy Program carried out in 2004.
The main branches of the plan are ensuring the pursuit of environment and economy, promoting of technology, raising public awareness, utilizing of policy measures, and ensuring international collaboration