Canada's environment commissioner is calling for a massive increase in efforts to combat climate change.

Released on Thursday, Johanne Gelinas's hard-hitting report is critical of the previous Liberal government but largely focuses on what the new Conservative administration needs to do better.

She said the government urgently needs a believable, clear and realistic plan to signficantly reduce greenhouse gas emissions.

The current government has said Canada cannot realistically meet its Kyoto target for reducing emissions, but Gelinas said if that's so, then new targets must be set.

Prime Minister Stephen Harper and Environment Minister Rona Ambrose are working on a new environment plan, Green Plan 2, but their comments to date suggest they intend to focus on smog rather than global warming.

The report from Gelinas could raise political problems for any Tory strategy that plays down global warming.

When asked Wednesday what the government will do about pollution in  Alberta's oil sands, Ambrose said her government will do more than the Liberals. The government already has taken action on mercury, she said.

"This government passed the first tough regulation on mercury. That took us just two months," she said.

"That is the kind of action Canadians deserve on the environment, and that's the kind of action this government will continue to deliver."

The World Wildlife Fund's Lorne Johnson said it may not be as simple as blaming Liberal inaction.

"After the release of this report, it will be hard for this government to fudge on the issue of climate change," said Johnson.

"If they try to dig in their heels under the guise of needing to do more consultations with the provinces and the industry, I think they will pay the price politically in Quebec and across the rest of Canada."

With files from the Canadian Press