TORONTO - It's not easy being green, but Ontario politicians have to stop being afraid of road tolls and a carbon tax if they want to help tackle global warming, Environmental Commissioner Gord Miller said Monday.

Miller's annual progress report on greenhouse gas reductions said the province was losing ground in the battle against climate change, and called for a comprehensive assessment of how road pricing can help lower emissions that contribute to the problem.

The transportation sector is the single largest producer of greenhouse gas emissions in the province, and money raised from road tolls and congestion fees could fund more public transit and make it a more attractive option for commuters, said Miller.

"Our report documents the significant environmental, social and economic benefits that many other jurisdictions across the globe have realized by putting a price on road use," he said.

The commissioner said that given the public's attitude, he wasn't surprised the Liberal government shot down the idea of road tolls when he raised it in a special report last December.

"Is it because the government was hard pressed against this or is it because they are concerned that the public isn't interested in this discussion?" Miller wondered. "It's my job to point out and try to get out to the public that this is a discussion we should have."

Transportation Minister Kathleen Wynne made it clear the Liberals won't be introducing road tolls any time soon, but said the government was willing to listen to the commissioner's ideas.

"There isn't a policy direction at this point to introduce new tolls on roads," Wynne told reporters. "However, we have to be open to having a conversation about how we fund transit infrastructure over the next generation."

The Progressive Conservatives and New Democrats oppose road tolls and congestion fees, but the Green Party of Ontario -- which doesn't have any elected members -- said it would support the two ideas if they were accompanied by income and corporate tax cuts.

"I think it's a conversation Ontarians are ready to have, but I think it has to be part of a comprehensive tax package," said Green Leader Mike Schreiner. "I think if you have road pricing and carbon taxes in place, people will make choices to go green."

The opposition parties also oppose the idea of a carbon tax, and the Liberal government prefers a cap and trade system, but that system appears years off in North America, warned Miller.

"Standing off and saying we're not going to participate in any discussion because we're afraid of the word 'tax' isn't productive," he said. "Cap and trade is not coming together, so this carbon tax discussion should be had. It's working in B.C. ... (although) I appreciate it's under attack."

British Columbia introduced a carbon tax in July 2008 that added about 2.4 cents per litre on fuel costs, including gasoline. Nova Scotia plans to create a carbon offset fund, but details of exactly how that would work will be hammered out over the next year.

Ontario Environment Minister John Gerretsen was lukewarm to the idea of introducing a carbon tax instead of pursuing a cap and trade system to try to reduce greenhouse gas emissions.

"Certainly a carbon tax is something to look at, but ultimately it's going to be government policy as to whether or not it be implemented," said Gerretsen. "Whatever measures that we can take to lower (emissions) we will certainly promote and advocate for."

The province also needs to set more aggressive targets for reducing greenhouse gases because the current goals were set three years ago, and scientific evidence shows "global atmospheric CO2 levels are reaching a dangerous tipping point," said Miller.