Villagers wade through flood waters in the village of Baseera near Muzaffargarh in Pakistan
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Climate change: Poorest most vulnerable

31 March 2014 Last updated at 19:20 BST

The impacts of climate change are likely to be "severe, pervasive and irreversible", according to a major report by the United Nations.

The report suggests rising global temperatures are likely to cause a higher risk of flooding and more extreme weather like heat waves.

The BBC's Science Editor David Shukman reports.