, more than 22 coal-fired power plants are planned for construction in Japan, following the switching-off of Japan's nuclear fleet after the 2011 Fukushima nuclear disaster. Japan ranks 20th in the 2018 Environmental Performance Index, which measures a nation's commitment to environmental sustainability. Japan is the world's fifth largest emitter of carbon dioxide. As the host and signatory of the 1997 Kyoto Protocol, Japan is under treaty obligation to reduce its carbon dioxide emissions and to take other steps to curb climate change. In 2020 the government of Japan announced a target of carbon-neutrality by 2050. Environmental issues include urban air pollution (NOx, suspended particulate matter, and toxics), waste management, water eutrophication, nature conservation, climate change, chemical management and international co-operation for conservation.