Polar bear numbers could drop a third by mid-century, according to the first systematic assessment, released Wednesday, of how dwindling Arctic sea ice affects the world's largest bear.

The U.S. Army Corps of Engineers on Sunday nixed plans for a controversial oil pipeline crossing in North Dakota, a major victory for Native Americans and environmentalists who had staged months of protests.

The pipeline had been set to cross under the Missouri River and man-made Lake Oahe, which are drinking water sources for the Standing Rock Sioux Tribe.

The heavyweights of world trade, including the United States, China and Japan, meet in Geneva this weekend to establish a list of environmentally friendly products for which tariffs can be eliminated or reduced.

The world's big cities will need $375 billion of investment to curb climate change, a large gathering of mayors heard in Mexico on Thursday.

"It is a lot, but there is no other option. Together we will seek that money," said the new president of the C40 network of big cities, Paris Mayor Anne Hidalgo.

Fighting climate change means different things in different cities, as this snapshot illustrates:

A young chimpanzee smuggled across Syria to northern Iraq three years ago was on his way to a sanctuary in Kenya Wednesday after three years in a private zoo.

The Arz-Ainata road was blocked by snow on Wednesday as the northern city of Tripoli witnessed material damage with the arrival of this season's first storm.

The EU on Wednesday unveiled "clean energy" plans to boost renewable use, cut waste and reduce subsidies for coal power in a bid to meet its commitments to the Paris climate deal.

The new metal dome encasing Ukraine's infamous Chernobyl nuclear power plant contains enough metal to build three Eiffel Towers with a few thousand tonnes to spare.

China could waste as much as half a trillion dollars on unnecessary new coal-fired power stations, a climate campaign group said Monday, arguing the world's top carbon polluter already has more than enough such facilities.