Organizers say they intend to send a message to leaders for their get-together Tuesday: make renewable energy a priority and forgo expansion of Canada's tarsands and associated pipeline projects.
They are hoping participants will clearly demonstrate that Canadians want to play an active role in determining future energy strategy.
Environmental groups say the provinces, while showing leadership, need to look beyond their own jurisdictions.
"What will be important at the end is what we see on the ground," said Patrick Bonin of Greenpeace. "If we don't see a dramatic increase in terms of solutions and actions taken by the provinces, we'll still be in trouble."
At their last meeting in January, the provinces said they were making headway on the so-called Canadian Energy Strategy, an initiative involving all 13 premiers that is centred on climate change and clean energy. They've committed to adopting it later this year.
They also discussed TransCanada's proposed Energy East pipeline — a $12-billion project that would carry oil from the western provinces to New Brunswick by using a repurposed natural gas pipeline and building an extension to connect it to the East Coast.
The completion date was extended this month to 2020 after the company called off plans to build a marine terminal in Cacouna, Que.
Saturday's demonstration will also urge premiers to take a firmer stand on projects like Energy East that environmentalists say will facilitate expansion of the oilsands.
"You can either protect our climate or you can develop the tarsands, but you cannot do both at the same time," said Karel Mayrand, Quebec director of the David Suzuki Foundation.
"We're worried that premiers will meet and say yes to protecting our climate and, at the same time, yes to oil infrastructure such as pipelines and expanding oilsands production."
One of the other stated goals of the Quebec summit is to determine what role the provinces can play leading up to the United Nations Climate Change Conference in Paris in late 2015.
Adam Scott of Environmental Defence said success will be defined by getting away from a patchwork of provincial policies and setting common goals. They could even agree to reduce their emissions so the country's overall carbon budget is actually met.
But getting there without federal involvement in co-ordinating and setting the national agenda will be challenging, Scott said. Ottawa has promised repeatedly to take action, set targets and then has failed to actually move forward, he added.
"We can't see effective climate action in Canada without the federal government," Scott said.
He said 80 buses are headed to Quebec City, with participants coming from various places, including Fredericton, Toronto, Edmonton and British Columbia.
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