Video from Insulate Britain
Insulate Britain protesters said they are "incredibly sorry" about any disruption, but are "determined" to continue their campaign even in the face of injunctions.
A total of 52 activists descended on junction 14 of the M25 at around 8am on Monday morning for their sixth road block in just over two weeks.
Some glued themselves to each other barriers, and the tarmac, and blue paint was sprayed onto the road.
The group, an offshoot of Extinction Rebellion, is calling on the Government to insulate homes across the UK to help cut carbon emissions.
Protesters have come out despite High Court injunctions which mean they face jail and heavy fines for blocking the major route.
A Met Police spokesperson said 53 arrests had been made and lanes re-opened at around 11.10am.
Dr Diana Warner, 62, a retired GP from Bristol who is a member of the group, said she was "determined to do everything she could" to force change.
"I'm here because of desperation, it's not an easy thing to do," she said.
"This is the fifth time I've been here trying to block a motorway because the only way to get the Government to listen is to disrupt things.
"I'm really sorry, but I'm determined to do everything I can to make us safe and change society ... we have to try."
Victoria Lindsell, 66, a volunteer language teacher, said: "We all understand the frustrations, but this is the only way to make the Government listen.
"We're incredibly sorry, we've all been stuck in traffic jams, but to be inactive is a crime.
"I'm wet through and I'm cold, it's not my choice but I cannot have the responsibility and not do anything about it.
"People get disrupted in the motorways nearly every day anyway."
Another protester, identified only as Emily, 22, from Manchester, said: "Insulating our homes is the most basic first step - it will get emissions down, create jobs and help families in fuel poverty, that's real levelling up.
"The Government knows what needs to be done. They just need to get on with it." After having been placed under caution, spokesperson Liam Norton said the group's demands were "simple" and a "no-brainer".
"We fully understand that this is affecting ordinary people ... but if this crisis isn't dealt with then within a few decades it's going to really disrupt this country," he told said.
"We'd just like to express to ordinary people that we're trying to protect this society of ours that we live in.
"The very fabric of our society is at stake and will be destroyed unless things are dealt with.
"We feel terrible about the situation and we are just asking for them to consider why it is that the Government won't make that meaningful statement and protect this country."
After being told by the group about their environmental concerns for the future, one motorist replied: "I've got to feed my kids now, I need my money now, to feed my kids now, but you don't get that.
"You don't get it. If you did, you wouldn't be blocking normal people like me, trying to get to work to feed my kids.
"You're ridiculous - go somewhere else and stop stopping people going to work."