We need eco-extremists - Miliband
The scale of the popular movement and the force with which activists and agitators deliver their arguments is key to the success of any future international agreement to tackle climate change.
"We need the utopians and we need the agitators," he said.
"We need the people who say that people like me aren't doing enough."
He spoke about the massive popular mobilisation of the Make Poverty History campaign in the run up to the Gleneagles G8 summit in 2005, saying that had made a huge difference to the outcome of the gathering of world leaders.
Mr Miliband told delegates how, at the time, musician-turned-campaigner Bob Geldof had shouted at him down the phone, arguing his case in no uncertain terms.
"Bob Geldof can be a pain in the ****, but it's incredibly important that people like that are part of the climate change movement," he said.
When the United Nations holds its climate change conference in Copenhagen in 2009, the outcome will be shaped in part by the apparent level of public concern, he said.
"When I came into this job I didn't know as much as I should have done about Copenhagen 2009 as a red letter day in relation to climate change," said Mr Miliband.
"Whether we get an agreement or not will be partly defined by the strength of the popular movement around the world."
He said it was vital for activists to form global networks that would help give their message more weight.
Government wants the world to reach an agreement on climate change, he said, but it would not be an easy task.
"Given the economic backdrop this is a very big challenge we face," said the Minister.
"This can't be done by government alone, it needs a popular movement to make this happen. That movement needs to do more to find its international voice."
He also commended the work of local councils and stressed the need for everyone to play their part.
"I think the work that local authorities are doing is incredibly important because it makes people in local areas change the way they live and change their ways for the better," he said.
"It signs people up and gets them involved in the bigger ideas about the need to tackle climate change.
"The most important thing of all is that people can say of us in decades to come 'these people saw the scale of the challenge, they saw the threat that was posed by climate change and despite tough times they did act and they did make a difference to ensure we met our obligations to future generations."
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