OTTAWA - It would cost $100 billion over four years for Canada to meet its Kyoto targets under a plan by Friends of the Earth and Corporate Knights magazine, one of the first attempts to put a price tag on addressing climate change.

Although the cost sounds staggering, it amounts to only $20 a week for the typical family, says Beatrice Olivastri, CEO of Friends of the Earth.

Based on the polluter-pays principle, the proposal would tax carbon fuels such as gasoline and coal, and redirect the money to new green technologies. It would include international emissions trading and the funding of emissions-cutting projects in the developing world.

So far the Green Party is the only federal party to embrace the concept of a carbon tax, but MPs from other parties suggested that the mood may be changing.

Liberal environment critic David McGuinty and New Democratic MP Paul Dewar praised the proposed plan at a news conference Wednesday, and said their parties are debating the idea of a carbon tax internally.

Toby Heaps, editor of Corporate Knights, said concern about global warming has risen to the point where Canadians are ready to make sacrifices to deal with it.

"There's a real, tangible awareness that something's wrong with the weather and the climate and humans are the cause of it and we can do something about it,'' said Heaps.

"I think that cultural awareness makes us ready today in a way we may not have been in the past. It's not free but it's not something that will stop the economy or break the bank.''

The federal government has repeatedly said that the Kyoto targets are unachievable without massive disruption to the economy. But Heaps said the cost of gasoline, for example, would rise by only a few cents per litre.

So far, the Harper government's proposals to curb climate emissions have consisted mainly of subsidy programs and incentives, like the previous Liberal plan.

The government is working on regulations for heavy industry but these would depend on "intensity targets'' which would allow emissions to continue rising.

"Everybody who knows this issue agrees that if you don't put a price on carbon you're spinning your wheels,'' said Heaps.

"Subsidy programs are like planting seeds in a bare desert, you won't get results, you have to make people pay for the privilege to pollute otherwise they'll do it with reckless abandon. If you don't put a price on carbon, if people are free to pollute there's no incentive to conserve or limit.''

The Harper government has ruled out the idea of a carbon tax.