Ontario Premier Dalton McGuinty says Canada has been 'punching below its weight' when it comes to tackling climate change. (CBC)

Ontario Premier Dalton McGuinty says the UN climate summit at Copenhagen was a "missed opportunity," and that Canada hasn't done enough to fight climate change.

A three-page accord signed in Copenhagen on Friday recognizes that an increase in global temperature should be kept to 2 C — the threshold that UN scientists say is needed to avert serious climate change.

But the accord, which was put forward by the U.S, China, India, Brazil and South Africa, is not legally binding and has no long-term global targets for emissions cuts.

"I think it's a missed opportunity. Just as a global citizen, I am disappointed. And I wish that we could have found a way — all of us, we, the people of this planet — to come together and better come to grips with what our shared responsibilities entail in a face of a global challenge," McGuinty told CBC news in a Monday interview.

"Hopefully over time we'll find some way to put some more teeth into that."

Prime Minister Stephen Harper, however, called the agreement "realistic" and said Canada was "very comfortable" with it. Canada was repeatedly assailed by environmental groups over the two-week conference for not doing enough to advance a robust climate deal, a position echoed by McGuinty.

"I think there's more that we could do, there's more that we should do as privileged global citizens," he said.

"I think Canada has been punching below its weight of late when it comes to climate change."

When asked specifically if he blamed the federal government for not doing enough on climate change, McGuinty said: "I think we've failed to find a way to come together as Canadians."

Regional differences on targets

The Ontario government has plans to reduce the province's greenhouse gas emissions to 15 per cent below 1990 levels by 2020. It has urged the federal government to adopt similar targets.

But the Harper government has opted for a more modest goal, saying it will cut greenhouse gas emissions by just 20 per cent from 2006 levels by 2020. Ottawa has also not ruled out giving special breaks to oilsands companies when it comes to greenhouse gas emissions.

McGuinty acknowledged there were regional differences on emissions targets, but suggested energy-based economies in the western provinces needed diversification because they are unsustainable.

"[Quebec Premier] Jean Charest and I see this pretty much the same," McGuinty said.

"I think we need to find a way to help Western Canada move beyond an economy that is overwhelmingly based on pulling stuff out of the ground. That's causing harm to our collective future," he said.

"We can't just tell them to turn off that tap if they have no other viable economic ... foundation. That's something that's a shared responsibility."

He said he's proud "that we're shutting down coal-fired generation," but acknowledged Ontario has to do more when it comes to climate change. Ontario has had some trouble implementing its promise to shut down coal-fired plants.

During the 2003 election campaign, McGuinty promised to shut down the coal plants by 2007. But the government has since backtracked, saying some coal-powered plants would continue to operate until 2014.