This has been a consistent theme for Miliband. He says "all of the great campaigns that we have seen: people demanded that they happened, not governments", citing anti-slavery and civil rights campaigns.
But Miliband also thinks that the possibilities of the global politics - while he has earlier stressed the many barriers and apparently 'compelling constraints' of domestic politics in the US, in China, in Europe, in the developing world - may be more optimistic than many people think.
A historic deal in December is possible he says.
The sense of a global movement is not what I thought it might be 9 months ago. The optimistic note is that the chances of a good global deal are stronger than i thought that they would be 9 months ago".
"Lots of clever people - including in the British government - said that the Obama administration will have too much on in his first year. The economy; healthcare. Perhaps he could act on climate change in his second year. But Obama said in his first speech to the Senate: send me a cap and trade bill. The Bill is more ambitious than his campaign promise, and would be a landmark piece of legislation".
"Other people told me that China are not going to be very interested. But I know that China is desperate for a global deal: they see the impact and want a deal".
While Australia had changed its position, many said it was not enough. But it had now stepped up its ambition.
"So don't let anybody tell you that Copenhagen is too complicated to resolve within the year. It isn't. The politics of what is needed is really quite simple. Those who say it is too complicated: it is a recipe for not getting a deal. It is about developed country ambition; it is about developing countries being part of it"; it is about financing what is needed".
So what is needed on the campaign?
it is about upscaling the campaign
It is about A simpler ask
"I know some people hate it when we mention Make Poverty History - but we do need the equivalent of 'debt, aid and trade'.
("Whatever people think about whether enough was done, I had 8 year olds in my constituency asking me about it, and as a consciousness raising issue that was very important, and that is why we need to see something similar", he adds later in response to a question).
It is about building the widest possible coalition
What is frustrating about the debate in the UK is that we have lots of people from business, charities, the third sector - but we haven't yet found a way of tapping into this, domestically and internationally, and really making that count.
"Why the campaign matters is that, without that, we won't get the focus, the ambition and the urgency that we need".
On a smaller scale, he also says that environmental movement is sometimes slow to recognise its successes, citing the campaign for clean coal in the UK: "there is no question that has changed the debate" so that coal fired power stations will not be built without addressing the issue of carbon.