Steps that must be taken

RAPID, far-reaching and unprecedented change is needed across the whole of society, the report says.

Renewables will have to supply 70% to 85% of electricity in 2050. There may be a small role for gas power, with technology that captured and stored its carbon, while coal would be virtually non-existent. Transport, buildings and industry must become significantly cleaner.

Taking excess carbon from the atmosphere requires measures such as planting forests or, controversially, burning plant material for energy and capturing the carbon to store underground.