The International Rebellion begins and Extinction Rebellion will be bringing London to a standstill for up to two weeks.
More than 100 people have been arrested in London as police deal with ongoing climate change protests, Scotland Yard said today.
The number of people held over the Extinction Rebellion demonstrations surged overnight after a police order restricted the protesters to a site at Marble Arch.
Following disruption in the heart of the capital on Monday, groups lingered on Waterloo Bridge and Parliament Square into the early hours of Tuesday.
Transport for London warned that some roads in Westminster and the West End remained blocked as the rush hour approached.
Police said that as of 6am there had been 113 arrests in total in connection with the demonstrations. The majority of the arrests were for breaching the order instructing protesters to stay only at Marble Arch.
Five of those arrested - three men and two women - were held on suspicion of criminal damage after protesters vandalised Shell's headquarters on Monday.
Campaign group Extinction Rebellion said it aimed to cause more than £6,000 damage so they can be tried by a jury in Crown Court.
Thousands of people gathered at five central London locations on Monday in a bid to bring the capital to a standstill. Thousands of people joined protests across central London to demand the government declares a climate emergency.
An Extinction Rebellion spokesperson said: "The rebels on the glass roofing [at Shell] have elected not to come down for twelve hours, forcing police into a protracted waiting game.
"During this time, the other three arrested earlier in the day have since been taken to police stations and released without charge, and have returned to find their two fellows still unarrested.
"Supportive rebels have thrown food and sleeping gear up to those on the roof – it looks like the police below have plenty of waiting still to do!"
Skateboarders replaced cars and lorries on Waterloo Bridge as the Thames crossing was closed to traffic and decorated with pot plants and trees.
Police on the bridge said there were no plans to move protesters on but indicated that the response could change if there is major disruption at rush hour.
One officer said yesterday afternoon: "It's been very peaceful so far. Everyone has been really pleasant. The only grief we've had is from passing motorists shouting at them to 'Get a job' - that's about as exciting as it's got."
A bright pink boat became the focus for hundreds of activists stopping traffic at Oxford Circus, where some used makeshift devices to lock their arms together.
Roads were also closed and drivers diverted around Marble Arch and Piccadilly Circus. At Parliament Square, people unfurled banners, held up placards and waved flags as speakers took to the stage.
Later the Metropolitan Police imposed conditions on the protesters, restricting them to gathering in the area around Marble Arch.
London's protests are part of a wider campaign which will see people in at least 80 cities in more than 33 countries hold similar demonstrations on environmental issues, campaigners said.
Organisers said: "The International Rebellion begins and Extinction Rebellion will be bringing London to a standstill for up to two weeks.
"They will be blocking five of the city's busiest and most iconic locations in a non-violent, peaceful act of rebellion where they invite people to join them for several days of creative, artist-led resistance."
Protester Olivia Evershed, 23, said: "I hope that it's really going to bring awareness about the emergency crisis that we are in, and encourage the government to act.
"They can change a few of the laws along with the Paris agreement so that we can really work towards achieving a practical target. We've got 12 years to act before there is irreversible damage to the environment and we start to see catastrophic changes. If we don't do anything to change this, our children will die."
Laura Jordan, 52, said: "This protest stands a good chance of working because we have a vast amount of ordinary people all saying the same thing. We need to change the way we do everything, the way we use fossil fuels. But this starts with the Government."
The movement has received support from actress and activist Dame Emma Thompson and former Archbishop of Canterbury Rowan Williams.
The XR spokesperson added: "At night Marble Arch was illuminated with XR projections reading ‘Act Now’, ‘Time is running out’, ‘Extinction Rebellion’ and ominous reminders of the degrees of global warming to date and tons of CO2 emitted.
"This set the stage for an evening performance by Nick Mulvey, with an estimated 300 or so rebels still holding the Arch by 8.30pm. By late evening, the roads were quiet, and, with blocks set up, rebels were confident that they would be able to hold this iconic site for the night."
Brendan Montague is editor of The Ecologist. This article includes copy from Press Association.