Rio Tinto will spend $US7.5 billion ($10 billion) over the next nine years to halve its carbon emissions in the belief that “radical”, immediate action is required for the world to decarbonise by 2050.

The dramatic escalation in the big miner’s climate ambitions included a goal to shift its Australian aluminium smelters onto a largely renewable power source by the end of the decade, and comes as Prime Minister Scott Morrison tries to secure support from the Nationals to take a net zero 2050 pledge to next month’s Glasgow climate summit.