Climate activists from the Last Generation group set up blockades to obstruct traffic along major routes through central Berlin on Monday, police in the German capital reported.
Seven activists glued themselves in place on Ernst Reuter Square and another on the main street that leads to the square, Hardenbergstraße, both in the Charlottenburg district, a police spokeswoman reported. Later reports referred to more than 20 blockades throughout the city.
Last Generation had earlier indicated their intention to shut down the entire city.
"We no longer accept the fact that this government does not abide by our constitution. We no longer accept that the government does not have a plan on how the destruction of our basis for life can be halted. We are now resisting," the activist group said.
There is no time limit on the campaign, which will end only once the demands are met. Berlin police deployed up to 500 officers to prevent the blockades or end them quickly.
The city's traffic authority reported that bus travel was subject to delays, detours and cancellations. They used Twitter to call on passengers to switch to rail services.
Last Generation is demanding the establishment of a citizen's assembly with its members chosen by lot and for a political plan to achieve the target of a rise in temperature of not more than 1.5 degrees Celsius to avert the worst consequences of climate change.