Road to Copenhagen

Representatives from some 180 countries agreed in Bali in 2007 to negotiate a successor for the Kyoto Protocol, which calls for cuts to greenhouse gas emissions and expires in 2012. In what at the time was called a "historic breakthrough," the ministers set 2009 as their deadline.

But the deal struck in Bali has frayed over the last two years. Despite renewed engagement on the parts of China and the United States - the world's two largest carbon dioxide emitters - a legally binding treaty calling for cuts to greenhouse gas emission is extremely unlikely.

Most experts predict only a non-binding political agreement to result from the two weeks of negotiations that begin December 7.

Deutsche Welle looks at some of the key issues climate experts will be discussing in the Danish capital, how they got there and the science behind the politics of climate change.