The protests were the second wave of an international series of demonstrations called the Global Climate Strike.
In Warsaw, protesters demanded that the government take urgent steps to reduce CO2 emissions and switch to green energy sources.
Some of the demonstrators were dressed all in green, others had badges with tree names.
Protesters gathered at Defilad Square in central Warsaw, from where they set off towards the houses of parliament.
They carried banners with slogans such as "Let's be eco-logical" and "Change the system, not the climate."
(ał-pk/gs)
Source: PAP