The three weeks of activity, which began this week, will run across stations including Magic 105.4 and Cool FM as well as Magic TV and 4Music.
The radio work will be supported by online activity on Bauer's radio websites as well as a viral campaign and direct work.
Companies including HSBC, eBay, Coca-Cola and IKEA have also backed the initiative.
Earth Hour will take place on Saturday 28 March at 8.30pm and aims to involve more than one billion people in 1,000 cities around the world; communities, businesses and governments are invited to switch off their lights for an hour to send a global message that we need to take action against climate change.
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