FACTBOX - What is the Kyoto Protocol?

Leaders from the Group of Eight rich nations are due to discuss at a summit this week a global deal to combat climate change, which would succeed the Kyoto Protocol when it runs out in 2012.

Here are some frequently asked questions about Kyoto:

* WHAT IS THE KYOTO PROTOCOL?

-- It is a pact agreed by governments at a 1997 U.N. conference in Kyoto, Japan, to reduce greenhouse gases emitted by developed countries to at least 5 percent below 1990 levels by 2008-12. A total of 173 nations have ratified the pact.

* IS IT THE FIRST AGREEMENT OF ITS KIND?

-- Governments agreed to tackle climate change at an "Earth Summit" in Rio de Janeiro in 1992 with non-binding targets. Kyoto is the follow-up and is the first binding global agreement to cut greenhouse gases.

* SO IT IS LEGALLY BINDING?

-- Kyoto has legal force from February 16, 2005. It represents 61.6 percent of developed nations' total emissions. The United States, the world's biggest source of emissions, came out against the pact in 2001, reckoning it would be too expensive and wrongly omits developing nations from a first round of targets to 2012.

* HOW WILL IT BE ENFORCED?