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COP21: Rallies mark start of Paris climate summit

Rallies have been held around the world, calling for a global agreement to combat climate change, as nearly 150 world leaders gather in Paris for a critical UN meeting on the subject.

The conference, known as COP21, will attempt to craft a long-term deal to limit carbon emissions.

The demonstration in Paris was marred by a small number of protesters who clashed with police.

Science Editor David Shukman reports.

  • 29 Nov 2015
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