The charity has turned to newly formed Red Dog Communications after a five-way pitch. Global Cool will specifically target people at festivals, motivating them to take more public transport and reduce their carbon footprint.
The campaign kicks off this weekend at the Download Festival in Donnington Park, Derby. Other festivals already partnered are Wireless Festival, T in the Park and V Festival.
Red Dog was set up in April by former consultants at The Media Foundry. The agency will target 18- to-45-year-old festival-goers through media outlets including Vice magazine and CBS Outdoor.
A free advice booklet on the positive aspects of using public transport will be handed out at the festivals and in next month's issue of Vice.
Red Dog will be touring festival sites in Global Cool's double-decker bus. It will also be promoting Global Cool's journey planner site, where users can plan their public transport trip door-to-door.
Exclusive interviews with festival bands will be posted on social media sites such as MySpace, YouTube and Spotify.
Red Dog consultant Sam Espensen said: 'We are targeting each festival with different content. Foo Fighters drummer Taylor Hawkins will go down a storm at Download, but not so well at Wireless.'
Espensen will report to Global Cool executive director Caroline Fiennes.
Red Dog will work alongside branded entertainment agency STREAM to deliver the integrated four-month campaign.