But just who are Extinction Rebellion?
Following the group's first demonstration last year on October 31, the climate change activists have courted headlines both in the UK and abroad, and have also recruited a number of high-profile supporters.
What does the group want?
Extinction Rebellion (XR) says direct action is needed to force governments to act urgently on climate change and wildlife declines and halt a “sixth mass extinction”.
It is calling for an ecological emergency to be declared, greenhouse gases to be brought to net zero by 2025, and the creation of a citizens’ assembly to lead action on the environment.
XR says the systems propping up “modern consumer-focused lifestyles” will lead to mass water shortages, crop failures, sea level rises and the displacement of millions.
“Only a peaceful planet-wide mobilisation of the scale of the Second World War will give us a chance to avoid the worst-case scenarios,” it says.
What are the groups' methods?
XR uses what is calls “non-violent civil disobedience” as the world has “run out of the luxury of time to react incrementally”.
Examples include blocking busy roads and bridges, spray-painting government buildings and activists chaining and gluing themselves to buildings including the gates of Buckingham Palace.
A colourful catwalk show took over London’s busy Oxford Circus junction in April to highlight the environmental impact of the fashion industry.
Protesters also once vandalised Shell’s headquarters, gluing themselves to windows and smashing glass revolving doors in a bid to cause more than £6,000 of damage – to enable them to have a jury trial in Crown Court.
A day later, around two dozen protesters occupied the International Criminal Court in the Hague, in the Netherlands, in a bid to have ecocide recognised as an international crime, the group said.
XR says it wants ecocide - the deliberate destruction of the natural environment - to be listed alongside crimes against humanity, war crimes, genocide and crimes of aggression.
How has Extinction Rebellion gained momentum?
In its first protest on October 31 last year, the group assembled a protest on Parliament Square in London, expecting a “couple of hundred people” – before 1,500 showed up.
The group said: “The energy was contagious! The next few weeks were a whirlwind.
“Six thousand of us converged on London to peacefully block five major bridges across the Thames.”
Chapters now exist in dozens of countries including the US, the Solomon Islands, Australia, Spain, South Africa and India, it said.
On April 15, protests in London began, with campaigners saying they will bring the capital to a standstill for up to two weeks.
Activists in at least 80 cities in more than 33 countries will hold similar demonstrations on environmental issues, campaigners said.
Do they have any high profile backers?
More than 100 academics - including the former Archbishop of Canterbury, Dr Rowan Williams - have given their backing to their radical views and methods.
Extinction Rebellion has grown into an international movement supported by celebrities and writers, calling for “radical change in order to minimise the risk of human extinction and ecological collapse”.
Oscar-winning actress Emma Thompson is reported to have pledged her support in a video calling on people to take to the streets.