Global society is going to have to make some "unprecedented" changes to how it consumes energy, travels and builds infrastructure to meet a lower global warming target.

Climate change experts say the world is at risk of an increase in heatwaves, flood-causing storms and drought in some regions - as well as the loss of species and coral reefs.

Keeping Earth's temperature rise to only 1.5C rather than the 2C goal agreed in Paris three years ago would have "clear benefits to people and natural ecosystems", a UN panel on climate change said.

Here's how failing to meet the 1.5C target would affect the world: