Extinction: Thousands of protesters against climate change block London bridges during a day of civil action

Environmentalists on Saturday held a series of disruptive demonstrations in London to highlight the government's "inaction" on climate change.

The Extinction Rebellion group said more than 6,000 people had blocked five bridges – Blackfriars, Waterloo, Westminster, Lambeth and Southwark – during the "Day of Rebellion" of direct action.

At least 22 arrested militants were on the occupied bridges after stopping the lines of communication shortly after 10 am

The metropolitan police said the protests had caused "a significant disruption of traffic" in central London.

Comparing itself to US civil rights activists, the protest group said that radical action was needed to "sound the alarm" about the looming climate crisis.

"We represent a very large number of concerned citizens – scientists, academics, politicians, teachers, lawyers, students, children, parents and grandparents," said organizer Tiana Jacout.

"We tried to walk, lobby and sign petitions," added Jacout. "Nothing has brought the necessary change. And no damage can be compared to the British government's criminal inaction in the face of climate and environmental degradation.

Writer George Monbiot attended the demonstration at Blackfriars Bridge. "Something I had been waiting for a long time is going on," he said.

"People risk their freedom in defense of the living world in large numbers. It is only when we are ready to take such steps that people begin to recognize the seriousness of our existential crisis. "

A separate rally will also take place on Parliament Square on Saturday afternoon. At a US climate protest in Washington, environmentalists tried to block traffic in front of the Trump International Hotel.

Extinction Rebellion said 50 people had been arrested as a result of several actions in London earlier this week, including spray painting walls surrounding Parliament.

Others chained themselves and stuck their hands at the entrance of the Ministry of Energy.

Activists also unveiled a banner reading "We're screwed" on Westminster Bridge.

The group wants the UK government to commit to reducing carbon emissions by 2025 and reversing policies that are incompatible with the fight against climate change.

Activists also demand the establishment of a "Citizens' Assembly" that allows ordinary citizens to participate in the creation of new environmental policies.

According to a new study by Australian and European researchers, dozens of major countries are implementing environmental policies that would lead to temperature increases of more than 5 ° C by the end of the century.

Last month, a landmark United Nations report warned that greenhouse gas emissions needed to be halved by the year 2030 to avert a global environmental disaster.

The group of scientists has discovered that the worst effects of global warming will only be avoided if the rise in global temperature remains below 1.5 ° C.