Activists who have blocked the the M25 six times in just over two weeks have continued their campaign despite an injunction which could see them imprisoned.
The group, an offshoot of Extinction Rebellion is calling on the Government to insulate all homes across the UK by 2030 to help cut carbon emissions.
As well as targeting the London ring road, protesters have blocked other major routes including the A1(M) and A20 near the Port of Dover.
The campaign, which is now in its third week, has seen well over 300 arrests.
Met Police arrested 53 people following a demonstration near Junction 14 of the M25, near Heathrow, on Monday morning.
But, in an open letter to Home Secretary Priti Patel the group said it is not backing down.
They said: “We are more fearful of the loss of our country than we are of you.
“You can throw as many injunctions at us as you like, but we are going nowhere.
“You can raid our savings.
“You can confiscate our property.
“You can deny us our liberty and put us behind bars.
“But shooting the messenger can never destroy the message: that this country is going to hell unless you take emergency action to stop putting carbon into the air.”
Monday’s protest saw some demonstrators glue themselves to each other, to barriers and the carriageway, and sprayed blue paint onto the road.
After having been placed under caution at the scene, Insulate Britain 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 the PA news agency.
“We’d just like to express to ordinary people that we’re trying to protect this society of ours that we live in.
“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.”
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.
She said: “I’m here because of desperation, it’s not an easy thing to do.
“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.”
The High Court granted an injunction in favour of National Highways, making some protest activities it a contempt of court carrying fines, prison sentences and asset seizures.
After being told by the group about their environmental concerns for the future, one motorist in traffic on Monday 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.”