The NSW government prepared sweeping climate change policies to decarbonise the state's economy only to have the plans shelved when Gladys Berejiklian became Premier, documents obtained by the Herald show.

The program included a proposal to "embed climate change consideration into government decision making", and was developed with the advice of the government-appointed expert panel, the Climate Change Council.

Policy switch: As environment minister Mark Speakman (right) prepared comprehensive climate policies that did not survive the elevation of Gladys Berejiklian to the role of Premier in 2017, documents show. Credit:James Alcock

Mark Speakman, then environment minister, led the work on two sets of policies that were to give substance to the government's aim to make NSW carbon neutral by 2050. The net-zero carbon goal was announced in November 2016 when Mike Baird was premier.

Mr Speakman welcomed the role of the council - a panel of 12 experts chaired by leading climate lawyer, Martijn Wilder - in a letter he sent in April 2016.