In a deliberate break with usual government practice, Defra has launched a "grassroots" effort to spread the message through local organisations, campaign groups and businesses.
The strategy was devised by Futerra, an agency that specialises in promoting sustainable development.
David Miliband, the Environment Secretary, has rejected calls from some environmental groups and MPs for a major government ad campaign to tell people how they can help to save the planet by changing their behaviour.
He said: "That programme of £12 million is being allocated to organisations such as the National Federation of Women's Institutes and the Scout Association.
We think it is better for organisations such as that to spread the message than to spend money on advertising showing the Government wagging their fingers at people."
The move follows market research for the department which suggested that TV, press and poster campaigns would have only a short-term impact on people's attitudes and behaviour.
Ministers believe a "bottom-up" campaign will have a longer-lasting effect.
"The average person is more likely to listen to peer groups and local organisations than a big government advertising campaign," one source said.
Defra's "tomorrow's climate, today's challenge" campaign advises interested parties to avoid trying to scare people or relying on their concern for their children's or their own future.