Tens of thousands of climate activists from different countries rallied in central Copenhagen on Saturday to highlight the need for sealing a "real deal" in the UN-led climate change talks.

The rally came as ministers were arriving for the higher segment of the talks that are tasked with achieving goals to avoid irreversible change in climate that scientists warn could be disastrous to the Earth.

Environmentalists who advocate waste recycle attend the Global Day of Action at parliament square in Copenhagen, capital of Denmark, on Dec. 12, 2009. [Xie Xiudong/Xinhua]

The activists converged on the city's Parliament Square, holding banners and listening to passionate speakers. "There is no Planet B," one of the banners read.

In a symbol of their call for countries to go environment-friendly, some demonstrators were clad in green and wearing green helmets.

Some activists called on rich nations to commit to deep emission cuts and deliver on pledges of financial and technological support to help developing nations adapt to climate change.

Environmentalists dressed as polar bears attend the Global Day of Action at parliament square in Copenhagen, capital of Denmark, on Dec. 12, 2009[Xie Xiudong/Xinhua]

"The world wants a real deal," another banner said.

Xiaojun Wang, chief media officer of the China branch of environmental group Greenpeace, a major organizer of the rally, told Xinhua that at least 50,000 people were taking part in the rally.

The crowd later marched towards the venue of the UN climate change conference, the Bella Center on the outskirts of the Danish capital.