Former prime minister Brian Mulroney was praised Thursday night as Canada's greenest prime minister, and gave his first public address in Ottawa in almost 13 years.

"We need to learn those lessons of careless development and neglecting to clean up after ourselves," Mulroney said.

"We need to learn especially in the North. The future of this country is going north, and it's time for a new northern vision: one of sustainable development, that preserves the Arctic wilderness, protects wildlife, and sustains a way of life for our indigenous peoples."

Mulroney went on to say that co-operation with America is crucial if Canada wants to win the fight against global warming.

"It isn't by lecturing the Americans on their record of emissions reduction that we'll succeed, especially when our own record is nearly twice as bad," he said.

Corporate Knights, a magazine that reports on corporate environmentalism, awarded Mulroney the distinction of being the greenest prime minister last year.

"I decided to assemble a jury of prominent Canadian environmentalists that represent the national organizations, and asked them which prime minister did the most for the environment," the magazine's Toby Heaps told Mike Duffy Live on Thursday.

"The replies started rolling in and I almost fell off my chair, because I started seeing Brian Mulroney's name coming up again and again."

In the end, Mulroney won 5-3 over Pierre Trudeau. But an attack of pancreatitis left him unable to attend the ceremony, which was postponed for about a year.

"He's at 100 per cent right now. He looks great, he feels great," his son Ben Mulroney said.

Mulroney, 67, took the stage at Ottawa's Chateau Laurier hotel, giving a speech in front of more than 300 people, including several leading politicians, lawyers and corporate giants.

Prime Minister Stephen Harper was among the guests, and told reporters earlier Thursday that the celebration showed a new understanding of Mulroney by environmentalists.

"At the time, I don't think there was any environmentalist who had anything good to say about Mr. Mulroney," Harper said of Mulroney's time as prime minister.

"Now he's regarded years later as the greenest prime minister. I believe the reason he's regarded that way is that he didn't pursue grandiose schemes and unworkable arrangements and the kind of problem we got into on Kyoto (greenhouse gas protocol). Instead, he decided to make real progress, concrete progress, on particular issues."

Mulroney's environmental record

Elizabeth May of the Sierra Club, who helped initiate Thursday's event, told The Canadian Press that Mulroney made the environment a priority for his government.

She said he was the first leader to sign the UN Framework Convention on Climate Change in 1992, which was a predecessor to the Kyoto Protocol.

Mulroney also managed to finalize an acid-rain treaty that sharply reduced sulphur emissions in eastern North America, despite misgivings by Ronald Reagan, the U.S. president at the time, according to CTV's Ottawa bureau chief Robert Fife.

One of Mulroney's lasting decisions was the $3-billion Green Plan, funding environmental research that produced data still widely used today.

"The truth is that for many years I've been saying that Brian Mulroney had an environmental records that puts subsequent prime ministers to shame," May told CTV News.

Thursday's dinner celebration proved to be the "hottest ticket in Ottawa," Fife said.

Tables costing $2,500 sold out within four days, quickly bought by corporations like SunLife and Enbridge. About 300 people were placed on a waiting list.

Among those lucky enough to attend were Quebec Premier Jean Charest, who served as an environment minister under Mulroney, former Liberal cabinet minister Sheila Copps, and comedian Rick Mercer, who gave an opening act.

With files from The Canadian Press