Former U.S. vice president Al Gore is not backing down from comments he made criticizing Canada’s oilsands, saying Thursday that while he can understand the desire to exploit “the great wealth” they can produce, they “represent one of, if not the, dirtiest source of carbon fuel in the world.”

In an interview with CTV’s Canada AM, Gore said he stood by his comments in a recent interview with the Globe and Mail, in which he said the “so-called resource curse” damages natural landscapes and contributes to “the reckless spewing of pollution in to the Earth’s atmosphere as if it’s an open sewer.”

Gore clarified Thursday that the statement was made as he talked about how the United States in fact burns more carbon fuels than Canada, and that “that collectively we who live on this planet are using the earth’s atmosphere as a dumping ground as if it’s an open sewer.”

However, he called products from the oilsands “the dirtiest fuels,” although he also said he understands the economic benefits they offer.

“I fully understand that with the U.S. failing to provide leadership, and the great wealth that can be produced by exploiting this poisonous source of fuel, it’s certainly easy to understand why the temptation is overwhelming,” Gore said. “But I do think it’s a mistake.”

He also challenged those who don’t like the sewer metaphor to explain what’s wrong with it, “Because the cumulative amount of man-made global warming pollution that we now put into the atmosphere traps enough extra heat every day to equal the energy in 400,000 Hiroshima atomic bombs. It’s a very big planet, but that’s an awful lot of energy.”

Earlier this week, Natural Resources Minister Joe Oliver called Gore’s comments to the Globe “over the top,” and he pointed out that the oilsands create jobs and represent 20 per cent of Canada’s GDP.

“We are immensely blessed to have the resources we have and if we develop them responsibly… we can ensure prosperity and security for Canadians for generations to come,” Oliver told CTV’s Power Play.

However, Green Party Leader Elizabeth May called Gore’s comments fair “because there is no other way to describe how we treat the atmosphere.” May called on the federal government to diversify Canada’s energy resources, including sun, wind and geothermal power.

When asked Thursday about what he thought of the Canadian government’s record on the environment, including pulling out of the Kyoto Accord and, more recently, the UN convention on droughts, Gore said he did not want to “enter into your domestic debates.

“I will say as well I’ve always had a deep and abiding respect for Canada. I say that not to flatter you or simply because I’m a guest, it’s just a fact.”

Gore praised Canada’s contributions to United Nations missions, “enlightened” social policies and open immigration policies.

“I think the recent policies on the climates crisis are really the exception rather than the rule,” Gore said.

“I and others had hoped that Canada, like Australia, would help to provide some leadership in the world community on this issue. But let me say again my country, the United States of America, has the biggest obligation to do that, so any criticism I have of the tarsands has to be placed in the context of the role I play in my own country, trying to get a change in policy there.”