Alongside Carat and MG OMD, Universal McCann and Brilliant Media have also been appointed.
Agencies on the roster will be selected to handle briefs on a project-by-project basis.
EdwardsGroomSaunders, Manning Gottlieb OMD and Media Planning were appointed to The Carbon Trust's media planning roster earlier this month.
The roster will be in place for the next four years and it follows a two-stage procurement process, undertaken as part of a full marketing and communications service review.
Earlier this month, The Carbon Trust appointed WCRS, Vallance Carruthers Coleman Priest and Rainey Kelly Campbell Roalfe/Y&R to its advertising roster, bringing to an end a seven-month statutory review of its arrangements.
The agencies beat off competition from McCann Erickson, Miles Calcraft Briginshaw Duffy and Leo Burnett.
In December, the government body appointed MRM Worldwide, Ogilvy Interactive, Tequila\London and WDMP to its digital roster.
The body is now poised to hire a lead advertising agency for a branding campaign to raise the profile of the government-funded body. The agency, which advises businesses and the public sector on reducing carbon emissions, is to issue a brief at the end of this week.
The brief will challenge agencies to devise a 12-month campaign drawing attention to the work undertaken by the trust.
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