US cities and states and Chinese cities have signed a declaration on climate change to cut greenhouse-gas emissions.
Atlanta, Houston, New York, Washington DC and several other major US cities and metropolitan areas have now agreed to new emissions reduction targets, with California state pledging an 80% cut by 2050.
Los Angeles, meanwhile, has signed a separate memorandum of understanding with the cities of Shenzhen and Guangdong to share best practice in reducing emissions, particularly from transport and buildings.
Meanwhile, China has established an Alliance of Peaking Pioneer Cities (APPC). All 11 cities and provinces in the APPC, including Beijing, have agreed to cap their CO2 emissions before 2030 when China's national target must be met. The combined annual emissions of the 11 cities are equal to those of Brazil or Japan.
Two of China's most polluting provinces, Jiangsu and Hebei, which regularly exceed China's own emissions limits, are not included in the declaration, however.