A group of former leaders and climate experts said the annual U.N. COP climate talks were no longer fit for purpose and needed to be reformed, publishing a critical open letter mid-way through what has so far been a fractious summit.

Call for change comes after host country Azerbaijan's president calls oil and gas a 'gift of God'

Leaders on a panel with members of the High Ambition Coalition, a group of nations that want to see strong climate action, highlighted the “inverted morality” of big emitters who aren’t taking responsibility for their impacts on countries who have the most to lose.