Celebrities including actor Jude Law and singer James Blunt have added their weight to a new online campaign calling for tough new environmental legislation.
The Big Ask online march, launched by Friends of the Earth, invites people to record a short video message to add to a website as part of efforts to try and secure a new climate change law requiring the UK to cut its carbon dioxide emissions each year.
Organisers hope the initiative will appeal to the country's "YouTube generation".
Razorlight's lead singer Johnny Borrell is one of the stars urging people to become involved in the campaign.
"It's absolutely crucial to make your voice heard by the elected government of this country; telling your MP that you care and that you want them to do everything they can to reduce carbon emissions," he stressed.
Pop stars and other celebrities are increasingly using their fame to campaign on environmental issues, with Borrell one of several artists set to take part in the series of Live Earth concerts this weekend.
Madonna, Duran Duran, Kasabian, Snow Patrol and the Red Hot Chili Peppers are among those due to play at the UK gig, one of eight line-ups arranged across the world to raise awareness of climate change.
Saturday's concert at London's Wembley Stadium has sold out.