Founded in Britain past year, Extinction Rebellion, also known as XR, now has chapters in about 50 countries.
"The October event is a peaceful rebellion in which we will try and wake the governments into declaring a climate and ecological breakdown".
More than 20 people were arrested by police in New York City's financial district after Extinction Rebellion climate protestors poured fake blood over the famous Charging Bull statue, a symbol of American capitalist might.
Ruth Ben-Tovim, an Extinction Rebellion spokesperson from Totnes who was on Lambeth Bridge this morning, told DeSmog: "Some people were trying to get through the cordon, so the police were pushing firmly back from that, and groups of officers did sweeps of arrests".
"The Canadian government is failing to act on the climate crisis and to protect its citizens", the letter reads.
Simultaneous protests took place in countries around the world, from New Zealand through Colombia to the Gambia. "And we are here to support it and get the message out as much as we can".
A total of 135 people have already been arrested at the London protests so far. The police told the activists through loudspeakers that they should go to the Museumplein, which they refused. Eight people were arrested during the raid.
In other places, police seized equipment including stages and loudspeakers meant for speeches before they could be put into use.
They say their big protest day will be Friday.
At sunrise, some were sleeping in insulated bags in the middle of the roundabout as police on motorbikes drove by.
Police eventually blocked off the top of Walterdale Hill and redirected traffic. In Sydney, hundreds blocked a road before being dispersed, and thirty people were charged.
The rallies came as German Chancellor Angela Merkel defended climate protection measures her government is due to approve on Wednesday but which critics have condemned as unambitious.
In Delhi, one of the world's most polluted cities, dozens of protesters staged another preliminary event on Sunday by holing a "die-in" on a road in the heart of India's capital.
Berlin's senator of the interior Andreas Geisel said the blockades would be observed and allowed to continue "for a while" as they could be regarded as spontaneous demonstrations, permissible under the right to demonstrate, wrote Der Tagesspiegel. Protesters ignored police calls for them to move to a nearby square.
Corinne Le Quere, professor of climate change science at the University of East Anglia said the battle to avoid catastrophic temperature rises will need to become a personal issue for everybody.
Demonstrators playing steel drums marched through central London as they kicked off two weeks of activities created to disrupt the city.
Police were seen cutting two protesters from a auto that had blocked Victoria Embankment, while campaigners also locked themselves to a mock Trident missile outside the Ministry of Defence.
Protesters in NY doused the city's famous charging bull statue with fake blood as part of their disruption.
Hundreds of activists barricaded themselves inside a Paris shopping centre for hours over the weekend, unfurling banners with slogans such as: "Burn capitalism, not petrol" above restaurants and fashion boutiques.
"She's now sat handcuffed on the ground with a red mark on her wrist".
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