Negotiators tasked with saving Earth’s climate system embarked Tuesday on an 11-day race to overcome decades-long disputes as experts pointed to a towering threat from coal.

A day after world leaders pledged to tame global warming, bureaucrats from 195 nations scrambled to shape a labyrinthine 54-page text into a blueprint that can be approved by December 11.

The goal — endorsed ringingly by around 150 heads of state and government at the start of the talks on Monday — is to commit every nation to a post-2020 pact to roll back emissions of carbon gases.