The pitch was overseen by the COI on behalf of the Department for Environment, Food and Rural Affairs and Department for Transport.
The two agencies were asked to submit proposals on how they would approach an integrated campaign encouraging the public to "Act On CO2".
The decision to use a single communications planning agency follows the recent announcement that Abbott Mead Vickers BBDO would take responsibility for all creative work. Previously, AMV and Leo Burnett had worked on the climate change initiative.
The consolidated creative business is worth £9m, with Defra's climate change account worth £5m, and the DfT's portion valued at £4m.