Global climate change is the single biggest environmental threat facing the planet.

The difficulties to reach a consensus on reducing global emissions have been enormous.

On more than one occasion, the Kyoto Protocol seemed doomed to failure. Nevertheless, Germany’s Green Party environment minister Jürgen Trittin is optimistic. "I believe that we will reach an overall positive conclusion here in Marrakesh", Trittin said.

The Kyoto Protocol has to be ratified by Russia and Japan in order to become a legally binding document. Marrakesh is the last chance for the parties to reach agreement. A compromise has to be worked out by Friday.