A prominent resource economist has pronounced himself disgusted with "dishonest" Conservative attack ads on a Liberal carbon tax proposal that's yet to be unveiled.

"The Conservatives -- and I say this with great sadness because I don't care which political party is in power -- but if we're going to do anything about climate change, we're going to have to be honest with people," Marc Jaccard of Simon Fraser University told CTV.ca on Tuesday.

"This is just totally dishonest."

On the weekend, the Tories previewed ads aimed at the proposed carbon tax, painting it as Liberal Leader Stephane Dion's "tax on everything."

The ads are to start running Tuesday.

Jaccard, a co-author of the recent book Hot Air, said the Conservatives' own policy on reducing greenhouse gas emissions won't work because it doesn't put a price on carbon for consumers.

"Their policy is to regulate industry and then have these offset loopholes where industry can subsidize consumers. But those are the types of policies that have never worked in the past," he said.

The Conservatives have said their plan will cut Canada's greenhouse gas emissions by 20 per cent below 2006 levels by 2020. But many environmental groups join Jaccard in saying the plan won't work.

If it did work, the Conservative plan wouldn't see Canada's Kyoto Protocol target -- to reduce greenhouse gas emissions by six per cent below 1990 levels by 2012 -- achieved until 2025.

The Liberals are said to be proposing putting a tax on carbon. While the policy has yet to be released, the Grits have said it will be "tax shifting" and "revenue-neutral," meaning that any revenue collected would be given back in the form of income or other tax cuts.

In the House of Commons' question period on Monday, junior minister Jason Kenney accused the Liberals of engaging in a massive tax grab to pay for billions in unbudgeted election promises.

Dion said the ads are "misleading and a lie."

Honest dialogue

"I'm not a fan of Stephane Dion, but when you get a politician out there that's trying to start an honest dialogue and say to people, 'you know what? We won't get our emissions down if there isn't a price on them and that's just the truth'," Jaccard said.

"And to see politicians saying, 'Maybe I can stay in power' or gain more power, or maybe a majority government, by distorting this" disgusted him, he said.

"Every one of those ads should say, 'Oh and by the way, your income taxes are going down if (the Liberals) do put in that tax,' but it's not there."

The Liberals say their plan, unlike the Conservative one, offers offsetting tax cuts.

Dion has said the plan won't drive up prices at the gas pump, where high oil prices have driven gasoline prices up to record levels.

Some of the Tory ads were to run at gas pumps in Toronto and other parts of southern Ontario.

But Fuelcast, the company that operates the pump-side advertising network, said Monday it won't run the ads.

The Conservatives have said they have a binding contract with Fuelcast, but if the company doesn't honour the deal, they will up their radio buy instead.