The group will meet three to four times a year and Horizons will pay for its administration.
The cost was unlikely to top $10,000, Horizons strategy and policy adviser Tom Bowen said.
The committee's meetings will be publicly advertised. The first is expected in December.
"In recent years activist groups have criticised local authorities – in New Zealand and overseas – for apparent inaction and a perceived lack of transparency in their responses to climate change," Bowen said.
"Establishing a Climate Action Committee and conducting its business in the public domain may go some way toward allaying those concerns."
Councillor Fiona Gordon liked the word "action" in the committee's name.
"It might be just a word but it has an important meaning, so I'm looking forward to some climate action at a regional level," she said.
Starting on September 7, and for the next two months, Horizons will engage with its community about climate change, using social and other media. The responses will be used in the risk assessment.
There will be a short survey but much of the consultation will take place online, using a tool called Social Pinpoint. People will be asked to mark things they value on an interactive map.
Those things could be tangible, such as buildings and native species, or intangible such as social cohesion and cultural values. People will be prompted by information on the council's climate change page, and by a list of possible values.
Those without access to the internet will be able to record their priorities on paper.
