Leading climate scientists say in order to stop global warming from exceeding 1.5C and causing a "climate catastrophe" urgent steps need to be taken now.

Research by the UN Intergovernmental Panel on Climate Change shows the world is now completely off track, heading instead towards 3C - twice the recommended rate of warming.

But how can just a few degrees make such a massive difference to our planet?

Why is 1.5 such an important number when it comes to climate change?

BBC Science reporter Laura Foster explains.

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