Canada's environment auditor says Ottawa is falling behind on its commitment to reduce greenhouse gas emissions and will likely not meet its 2020 goals.

In his latest report, Commissioner of the Environment and Sustainable Development Scott Vaughan says Canada would need to reduce emissions by 178 million tonnes over the next eight years in order to meet the set targets -- an unlikely feat.

"In comparison, the 2011 Climate Change Plan for the Purposes of the Kyoto Protocol Implementation Act reported actual reductions totalling six million tonnes for 2008 and 2009," his report states.

Canada has committed to reducing greenhouse gas emissions to 17 per cent below 2005 levels by 2020. In 2005, 731 megatonnes of greenhouse gases were released into the air.

Vaughan said Canada, which pulled out of Kyoto last year, is taking a sector-by-sector approach to reducing greenhouse gases, which is piecemeal and lacks coherency.

His report says Ottawa has not done a proper analysis of the costs associated with meeting the emissions goal. That's ironic, he suggested, because the Conservatives justified the decision to leave Kyoto by saying it was too expensive -- estimated at $14 billion in December of last year.

"Accordingly, I expected that the government would have calculated the projected costs to the Canadian economy of its regulatory approach to meeting its new target. ... Right now, it has not done so. The result is that Parliament lacks a full picture of the combined costs of reaching the 2020 target," he said.

"I hope I'm wrong," Vaughan said of his analysis on CTV's Power Play later Tuesday.

"This is a costly legacy we're leaving to future generations."

Environment Minister Peter Kent fired back in a news release, saying his government has done much more than previous administrations to reduce emissions.

"Our government is committed to ensuring an environment that is clean, safe, and sustainable for all Canadians, while creating jobs and promoting economic growth," Kent said in a statement.

Vaughan delivered more bad news Tuesday, noting that Ottawa is on the hook for billions of dollars to clean up contaminated sites across the country and fix other problems caused by the lack of proper environmental regulations in the past.

The estimated cost of cleaning up those sites is $7.7 billion, but the government has only set aside a fraction of that, Vaughan said. His audit found a $500-million shortfall to deal with the sites that have been assessed so far.

Most of the contaminated sites, including abandoned mines and industrial fields, date back to between 1940 and 1970, before strict environmental regulations were put in place.

"This is a cautionary note not to repeat the mistakes of the past. Canadians won't put up with it and we can't afford it," Vaughan told Power Play.

But Michelle Rempel, Kent's parliamentary secretary, told Power Play that the government is only halfway through a 15-year site cleanup plan and there is still more work to be done.

In his report, Vaughan also said Ottawa has been slow laying out what future environmental regulations will look like. As a result, businesses have not had time to make the necessary capital investments, or to implement the new equipment needed to achieve the reductions by the target year.

"Although the federal government has begun to lower greenhouse gas emissions, right now the reductions are not happening fast enough to meet the 2020 target," Vaughan said.

"I look forward to seeing the details of the sector-by-sector approach as they are announced and implemented."

Green Party Leader Elizabeth May said Vaughan's report continues to highlight the Conservative government's poor record on environmental issues.

May and NDP environment critic Megan Leslie told Power Play that the Conservatives are "so blindly driven by oil" that they are neglecting to address the environmental impact of the industry, particularly in Alberta.

"What about a little prevention? We only have one chance to get this right," Leslie said.

Rempel retorted by pointing out that Canada's greenhouse gas emissions remained stable in 2010 despite economic growth after the 2008 global recession. That means that the government is taking a balanced approach to stimulating the economy and protecting the environment, she said.

Vaughan also said it's time to change the view we take towards business practices and environmental policies, saying it is no longer necessary to choose one or the other.

Rather, he said, the most sustainable and successful businesses are the ones that incorporate strong environmental policies into their everyday practices. He cited the Royal Bank of Canada, The Co-operators, Loblaws and Tim Hortons as examples.

With files from The Canadian Press