The approach is a first for Horizons and is the first time iwi representatives will be formally appointed to any Horizons committee and have full voting rights.
Tangata whenua representatives will be appointed by the committee based on recommendations from iwi leaders and considering the skills, attributes, or knowledge that can assist the work.
Councillor Keedwell said the committee would use scientific evidence and mātauranga Māori to achieve climate change mitigation and adaptation.
"This committee gives regional leaders the chance to create a genuine and enduring partnership between iwi, central government, and local government – this will be integral to making real change," Keedwell said.
"We will also share information, facilitate collaborative action to reduce greenhouse gas emissions and prepare for climate change impacts."
Councils across the Whanganui-Manawatu region were already actively working to make a positive impact on the environment and build resilience to climate change, Keedwell said.
This included projects like the Sustainable Land Use Initiative to decrease erosion in hill country, helping to reduce sediment loads in rivers.
Horizons is seeking feedback on its draft Long-term Plan. Included in the Long-term Plan is a proposed new dedicated activity for climate change, which aims to respond explicitly to climate change risks and co-ordinate the regional council's work.
"The purpose of the activity is to identify risks associated with climate change, ensure the transition to a low-emissions economy where lifestyle is supported and barriers are removed, and communities, councils, and government work together effectively," Keedwell said.
"This new activity provides the opportunity to have a dedicated workstream with the direct purpose of adapting to and mitigating climate change effects."
The Climate Action Joint Committee will meet at least twice per year with the next meeting in September.