The Climate Justice movement has finally burst onto the scene at the UN climate summit in Copenhagen.

This morning, thousands of activists from South and North marched to the Bella Centre and tried to get in, to express their disgust with the way the talks are selling us all out, and to hold a Peoples' Assembly for Climate Justice instead. At the same time about 200 of us on the inside marched out to try and meet them. Both Reclaim Power marches ran slap bang into the less-than-friendly arms of the Danish police...

Those of us in the rare position of being allowed access to this vortex of privilege, profit and power-brokering gathered around 10am in the central hall. At the heart of a media scrum, we waited until we'd heard that our brothers and sisters outside had got close to the fence. Then we marched out.

Led by Indigenous Peoples, and attracting members of developing country delegations, we sang, cheered, and chanted our way through the building. No-one knew what the consequences of leaving would be for us. Would we be arrested? Barred from the rest of the conference? Our organisations permanently blacklisted by the UN?

We knew all of these - and who knows what else - were possible. Yesterday, Dr Tadzio Muller, one of our number, had been arrested just outside after the Climate Justice Now!/Climate Justice Action press conference about today's protest. This committed nonviolent activist has been fingered with the ludicrous charge of 'violence against the police'. Then first thing this morning, members of campaign groups Friends of the Earth, Avaaz and TckTckTck (who couldn't be more fluffy) arrived at the Bella Centre to discover that, without explanation, the UN wasn't letting them in. Friends of the Earth staged a sit-in for several hours in the registration area, but to no avail. The UN's attempts to stifle any criticism of the pitiful state of the climate talks - even from the most mainstream of NGOs - appears to know no bounds.

Knowing all these risks, we kept marching. The future of humanity is, after all, at stake, and our so-called leaders are failing us totally. So we marched out of the centre, into the freezing Copenhagen air. As flakes of snow drifted down, we kept up the noise levels and marched towards our friends outside.

We got close, but not close enough. Riot police stopped us on the only bridge across the canal. After a stand-off, we decided we were determined to join the Peoples' Assembly, and tried to push forward, risking violence and arrest. Right on cue, the one-sided violence began. Rows of rabid riot police pushed us back, raining down baton blows on all those they could reach, ignoring our hands in the air and our chants of 'We are peaceful, what are you?!' People bravely stood their ground. Then the cops charged, sending some of my friends flying and dragging everyone off the bridge. It became clear that there was no way they were going to allow us to connect with our movement and discuss the real solutions to climate change.

Meanwhile, mass arrests were taking place on the other side of the fence. Baton-happy cops used pepper spray, tear gas and dogs to try and contain protesters intent on getting through the fence. Nevertheless, the Peoples' Assembly took place. Activists from the global South spoke about their struggles against the devastating effects of both climate change and the 'solutions' rich countries are imposing on them - like emissions trading, biofuels and nuclear power - that actually make things worse. Then people had meetings in smaller groups about how to work together in solidarity, to sort the climate crisis out ourselves. I'm gutted I wasn't there as it sounded truly inspiring.

When we got back to the Bella Centre we discovered that the UN have now barred all NGOs from entering, for the rest of the day. Tomorrow they will only let in 1000. On Friday, a piddling 90. It's full-on censorship of civil society from here on in, it seems. However, I flashed my press pass and swanned back inside. Hah!

Far from being the hermetically-sealed cavern of spin that the Danish Government and the UN are desperately trying to maintain, this place is now rocking from the repercussions of the protests. Inside the main plenary, Heads of State are taking it in turns to address the conference. At one point activists disrupted proceedings, shouting 'Climate Justice Now!' which drew claps from many delegates. Then Venezuelan President Hugo Chavez took the floor, pointing out that if the climate was a bank it would have been saved by now, saluting the protesters outside, and even using our slogan: 'change the system not the climate'!

This feels like a tipping point. Footage of police violence against peaceful protesters is flying around the world, the UN's reputation is in tatters, and no matter how many people they bar from this building, they can't prevent our message from being heard. No-one, not even the UN, can shut Chavez, or Morales, up...!

The Copenhagen talks look set to remain deadlocked. It's all-too possible they will collapse. Industrialised countries appear completely uninterested in addressing what's really driving climate change - fossil-fuel dependent growth-oriented capitalist economies, and unable to countenance the changes that need to take place - a rebalancing of power, resources and rights from the rich North to the poor South. As far as I'm concerned the sense of doom now pervading the proceedings is to be welcomed. No deal is better than the terrible deal the US and its fellow bully-boys are now brutally trying to force developing countries to accept.

Of course, it's also really really bad, because we're on a very tight schedule here, and we have such a terrifyingly long way to go.

But today I'm feeling hopeful. Because today, undaunted, unintimidated, and in the knowledge that we are here to represent many millions of people, we began the process of reclaiming power. And not a moment too soon.