A total of 52 people were arrested Monday after environmental activists took to the streets of central London, blocking roads as they demanded the British government immediately end investment in fossil fuels that are driving climate change.
Extinction Rebellion's fifth mass protest targetted what it called the "root cause" of the climate and nature crises.
Demonstrators blocked roads in central London, including around Trafalgar Square.
Activists also set up a large pink structure at the junction of Long Acre and Upper St Martin's Lane with the words "come to the table" written across it to highlight the right everyone has to have a say in how to tackle the crisis.
The giant "table" containeds built-in lock-ons so protesters could attach themselves, sleeping quarters and its own stereo system, and activists were preparing to stay and occupy the site.
A visible heavy police presence surrounded the "Impossible Rebellion" protests, which are expected to attempt to disrupt London over the next fortnight, but no arrests had been made by Monday afternoon.
Demonstrations scheduled in central locations included St James' Park, Piccadilly Circus - similar to those carried out in 2019 - but more are due to take place in both north and south London.
The Metropolitan Police said a "significant" operation would be put in place to manage the protests over the busy bank holiday weekend, but acknowledged the activists' "important cause."
It confirmed that as of 10:15 pm (2215 GMT), some 52 arrests had been made for a "variety" of offences. The force added 10 arrests were made on Sunday.
In a statement ahead of the protests Extinction Rebellion, which has gained support of celebrities including comedian and author Stephen Fry and actor Jerome Flynn, said they would "target the root cause of the climate and ecological crisis - the political economy."
Gail Bradbrook, Extinction Rebellion co-founder, said: "Our leaders in Government and Business have been failing us for years, they are taking us over a cliff.
"If they are in any way serious about tackling this existential crisis then they would immediately stop financing fossil fuels, because continuing to pour petrol on a fire is an obvious sign of insanity.
"Why don't they act? They are wedded to a corrupt political economy, centred in the City of London, that extracts vast profits from communities and nature, and depends on destructive economic growth for its survival.
"We need to tell the truth, humanity has to change course, we have no choice."
Campaigners held placards with messages including "Code red, where's the action" while four people were dressed as the sea in a warning over rising sea levels.
A first-time climate protester said Extinction Rebellion's controversial methods are "necessary behaviour."
Maddy Hayley Thomas, 33, said: "What is extreme is the fact that the Government, huge corporations, all of our system is allowing the devastation to our planet, to the global south."
In a video shared on Twitter, Fry praised the group for attempting to "make politicians really recalibrate, realign, revolutionise politics" through their "mucky" and "disruptive" demonstrations.
Flynn attended a protest on Sunday evening in which three activists scaled the entrance of the Guildhall building in central London.
Extinction Rebellion vowed to return to the streets earlier this month following a string of victories in court which saw activists successfully appeal convictions for previous stunts.
Their latest protest comes after a major science review by the UN's Intergovernmental Panel on Climate Change confirmed that human activity such as burning fossil fuels was unequivocally driving the climate crisis, with impacts such as deadly heatwaves, floods and storms already being felt.
In November, the UK will host the international Cop26 summit where the pressure will be on world leaders to increase action to urgently cut greenhouse gases and avoid even more dangerous global warming.
