Hundreds of people will gather at Jubilee Gardens on London's South Bank at 9am to form a human version of the Stop Climate Chaos logo for an aerial photograph.
The campaign is the invention of the Climate Movement, a broad-based coalition of charities, NGOs and other groups that has been meeting since last year in order to find a way of moving the issue of climate change out of the "green ghetto" (Third Sector, 29 June). Its founding members are WWF, Greenpeace, Friends of the Earth, People & Planet and the RSPB.
More groups have joined recently, including Christian Aid, Oxfam and Cafod.
Ashok Sinha, campaign director at the Climate Movement, said he hopes Stop Climate Chaos will pack a punch at least equal to Make Poverty History.
The campaign poster claims: "Without urgent action, climate change will devastate life on earth. Before this decade is out world leaders must have lived up to their duty to prevent catastrophic climate change."
The alliance adopted the campaign name from the WWF's own climate campaign.
Paul Valentin, international director at Christian Aid, said: "Our goal is to link our work abroad to tackling climate change and to make that link more explicit."