Nine Insulate Britain activists have been jailed at the High Court for breaching an injunction designed to prevent the group's road blockades.
Insulate Britain, an offshoot of Extinction Rebellion, have been causing havoc on the M25 for the past two months.
Campaigners of the environmental group began a wave of protests in September and have blocked the M25, other roads in London including around Parliament, roads in Birmingham and Manchester and the Port of Dover in Kent.
They were in September given a High Court injunction restricting them from taking part in disruptive protests.
The protesters were warned that if they breached the order they would face time behind bards, but they nonetheless defied the warning to keep protesting against carbon emissions.
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Nine of them have now been jailed, namely Ana Heyatawin, 58, and Louis McKechnie, 20, who got three months while Dr Ben Buse, 36, Roman Paluch-Machnik, 28, Oliver Rock, 41, Emma Smart, 44, Tim Speers, 36, and James Thomas, 47, all received four-month sentences.
The submissions made by Ben Taylor, 37, to the court on Tuesday were described by Dame Victoria Sharp as "inflammatory" and a "call to arms", and he was therefore given a longer sentence of six months "to deter (him) from committing further breaches".
An Insulate Britain activist addressing the media outside the Royal Courts of Justice said Emma Smart, one of the nine, had announced her intention to go on hunger strike after being jailed for four months.
The sentencing judge, sitting with Mr Justice Chamberlain, said there was no alternative to custodial sentences given that the group's actions were so serious and they had made it clear they intended to further flout court orders.
She said: "The defendants, or some of them, seem to want to be martyrs for their cause and the media campaign surrounding this hearing appears designed to suggest this.
"We, however, have to act dispassionately and proportionately."
All nine defendants had admitted breaching High Court injunctions designed to prevent disruptive protests, in regards to their part in a blockade at junction 25 of the M25 on October 8.
Following the sentencing on Wednesday, Britain Insulate took to Twitter to say: "This morning our #InsulateBritain supporters have been sentenced.
"We are being failed and betrayed by our government."
The group added: "The 9 chose not to standby and be complicit in genocide. We remain resolute and determined."
Raj Chada, solicitor at Hodge Jones and Allen law firm who supported the protesters, said: "With these prison terms, the long and honourable tradition of civil disobedience is under attack again.
"Rather than leaving courts to imprison those that raise the alarm, it should be the Government that acts to protect us against the climate crisis."
So far at least 161 activists have been involved in the protests and police have made at least 860 arrests.
The High Court has so far issued five injunctions to prevent protesters from blocking roads.
They include four injunctions granted to National Highways, banning demonstrations on the M25, around the Port of Dover and on major roads around London, and one to Transport for London (TfL).
TfL was granted a civil banning order aimed at preventing protesters from obstructing traffic on some of the capital's busiest roads.
Those who breach the injunctions could be found in contempt of court and face a maximum penalty of two years in prison or an unlimited fine.
A statement released by the nine defendants following their sentencing reads: "Over the last nine weeks, 174 ordinary people have held the Government to account, asking that they deliver on their most basic of duties, to protect the British people, the economy and all we hold dear in our society.
"Your Government has now chosen to act. It has chosen to imprison us for this demand.
"By imprisoning us, the Government shows its cowardice. They would rather lock up pensioners than insulate their homes.
"They would rather lock up teachers than create thousands of proper jobs.
"They would rather lock up young people than take practical steps to reduce emissions.
"They will lock us up and leave thousands to die of cold this winter. We knew we would face prison when we took this action, but we could not stand by while the Government betrays the general public."
The activists' statement continued: "Following the widely recognised failure of our Government at Cop26, we are continuing to ask them to get on with the job - of cutting carbon emissions, of insulating cold and leaky houses, of protecting the people of this country from climate collapse - because the lives of our children and those of all future generations hang in the balance.
"To the Government we say, you can't imprison a flood, there are no unlimited fines against a famine, you can't bankrupt a fire.
"To the public we say, no-one is coming to save you. In the past, when governments have failed to protect their people the right thing to do is to highlight this injustice, breaking the law if needed, this is what the suffragettes and Martin Luther King did, and it is what Insulate Britain has done.
"We call on you to recognise that you also have a duty to act, as our Government is betraying us.
"They can't even act to insulate Britain. What hope do we have of them protecting our children, our economy or our country?"
