The prime minister is to pledge UK leadership in the international battle against climate change.
He is due to launch a document showing what the UK will offer to the Copenhagen conference tasked with forging a new global climate agreement.
Climate Secretary Ed Miliband described the conference as "make or break time for the climate".
The Road to Copenhagen document will outline plans for ongoing emissions cuts in the UK.
It will also contain practical advice to people on how they can cut emissions and often save money too.
The document will focus on UK ambitions for the Copenhagen conference and also for the G8 meeting, soon to take place in Italy.
At that summit, leaders of the world's top polluting nations - including emerging economies - will attempt to clear a path for a global deal.
See the BBC News story