FACTBOX: Milestones on the road to Copenhagen climate talks

(Reuters) - Environment Ministers from about 190 nations gather in the Danish capital at the end of the year to try to agree a broader global pact to fight climate change.

The aim is to build on the existing Kyoto Protocol by ensuring rich nations sign up to deeper emissions cuts while offering greater assistance to developing countries to help them curb greenhouse gas pollution as well.

Following are key points about the U.N.-led negotiations.

WHAT IS KYOTO?

Only 37 relatively developed countries have agreed to targets for 2008-12 under a principle that richer countries are most to blame. They range from an 8 percent cut for the European Union from 1990 levels to a 10 percent rise for Iceland.

The United States, long the world's biggest source of emissions but which has been surpassed by China, came out against the pact in 2001. While the Obama administration is too late to sign up to Kyoto, the government has already set a target to cut emissions back to 1990 levels by 2020.

WHAT HAPPENS NEXT?

Four more rounds of formal negotiations are scheduled before the Dec 7-18 talks in Copenhagen. These are June 1-12 in Bonn, Germany; Aug 10-14 in Bonn; Sept 28 to Oct 9 in Bangkok; and Nov 2-6, at a venue yet to be decided.

In addition, heads of state and government will gather in September at a U.N. climate change summit in New York and President Obama will host a major economies forum on the sidelines of the G8 in Italy in July. Two other meetings convened by the United States will take place, one probably 26-27 May in Paris and another in June.