Prime Minister Kevin Rudd demands real action on climate change at Copenhagen climate change conference

UPDATE 9.22pm: PM KEVIN Rudd has delivered his last ditch play in a speech to the Copenhagen climate change conference.

PRIME Minister Kevin Rudd has delivered his last ditch play to the Copenhagen climate change conference in an address to the main session as an estimated 140 world leaders file into the meeting.

As hopes of a solid outcome at the mega-talkfest cool as quickly as the snow carpeting the Danish capital, Mr Rudd lectured delegates to consider their children, and their children's  children when they determine their final position.

He said it was now a matter of urgency that the biggest economies find a way to cut another five gigatons of carbon from the atmosphere by 2020 - the amount needed to limit warming to the maximum of another 2 degrees.

"Climate Change is no respecter of culture, it is no respecter of nations,'' he said.

Ratcheting up the emotional angle, he told the conference of a book of letters provided to him by six year old school children. One of the children, "little Gracie''  from a Canberra primary school, had urged him to remain strong in the talks.

"I fear we are on the verge of letting down little Gracie and every child of the world,'' he said.

Mr Rudd's comments appeared to open the door to a so-called second track agreement - that is the idea of extending the Kyoto protocol agreement and also establishing a second legally binding agreement to compel other non-Kyoto economies, particularly the US and China the world's largest emitters.

He appealed to leaders to act not just as politicians but as human beings, as mothers and fathers, husbands and wives as he spoke of the need to act to save the Great Barrier Reef and countless villages and communities across the world.

"History is calling on us to develop a grand bargain between the past and the future,'' he said as he outlined the key areas of difference still to be resolved.

He said it was time to stop talking and start acting.

"Words without deeds are a dead letter,'' he said.

The speech appeared designed to cut through national rigidities, and entrenched positions to get to the heart of the political leaders gathered there.