EDMONTON -- Alberta is forced to reconsider its options in the face of a Thursday ruling that Canada's federal carbon pricing is constitutional, a decision the province's premier says erodes his jurisdiction and undermines the constitution.

At a news conference hours after the landmark Supreme Court of Canada ruling, Alberta's Jason Kenney said his government would be consulting its residents and provincial allies on next steps.

He said all options remained on the table – choosing not to rule out Alberta implementing its own carbon tax in lieu of the federal one, as the previous NDP government had done.

"When it comes to complying with this decision, we're going to do it in a way that imposes the lowest possible cost on Albertans," Kenney told reporters.

"The key criteria will be: which approach imposes the least damage on jobs and the Alberta economy and the least cost on Alberta families?"

The work is something Alberta NDP and Official Opposition Leader Rachel Notley says Kenney's government should have started when it was elected.

"He has been distracted for two years with this particular battle, which many people suggested he was not likely to win," she told reporters.

"It's not easy and the work doesn’t just happen."

'WHERE'S THE WIN FROM THIS 'FIGHT BACK' STRATEGY?'

The Supreme Court's split decision upholds a pivotal part of the federal Liberal government's climate-change plan, accounting for at least one-third of the emissions Canada aims to cut over the next decade.

In the written ruling, Chief Justice Richard Wagner called climate change a real danger and said evidence shows a price on pollution is a critical element in addressing it.

"It is a threat of the highest order to the country, and indeed to the world," Wagner wrote for six of the nine judges. Given that, he said, Canada's evidence that this is a matter of national concern, is sound.

"The undisputed existence of a threat to the future of humanity cannot be ignored," Wagner wrote.

Justice Suzanne Cote dissented in part, agreeing climate change is an issue of national concern but taking issue with the power the federal cabinet gave itself to adjust the law's scope, including which fuels the price would apply to. Two other justices argued Canada had not shown that climate change reaches the level of national concern. They objected the precedent the majority's decision sets would allow Ottawa to set minimum national standards in all areas of provincial jurisdiction.

Kenney said Thursday, "We are very concerned about how the door has been opened to a potentially unlimited exercise of the federal reserve powers over areas of exclusive provincial jurisdiction."

But Mount Royal University political scientist Duane Bratt noted: "(Kenney) said it's a legitimate decision, but he never quoted from the majority. He only quoted from people who agreed with the Alberta government."

Bratt doesn't see the ruling as a federal intrusion on provincial jurisdiction, and pointed to its "narrow" application to carbon pricing.

"The environment is one of those co-jurisdictions. It was not identified in the constitution," he told CTV News Edmonton.

Nor does he see it affecting Alberta's challenge of Ottawa's Bill C-69 environmental assessment law, with which Kenney said Thursday the province plans to continue.

Bratt called it consistent with the United Conservative leader's approach.

"This is part of his 'fight back' strategy, but aside from winning the 2019 election, almost every subsequent fight they've lost. They've lost this court case. They've lost the Keystone XL play. The war room has been a disaster. The Allan inquiry [into 'anti-Alberta energy campaigns'] has been a disaster. Justin Trudeau got reelected in 2019," Bratt listed.

"Where's the win from this 'fight back' strategy?"

Notley said: "The 'fight back' strategy was always about trying to make other people responsible for the things that Jason Kenney was failing and is failing to deliver."

'DOESN'T MEAN THAT THE FEDERAL GOVERNMENT SHOULD'

Kenney's party campaigned on a promise to scrap the previous NDP government's carbon tax program and challenge the federal pricing scheme.

Alberta, Saskatchewan and Ontario all challenged the law in court, saying it infringes on the provinces' taxing powers and a constitutionally protected right to develop their own natural resources.

As of December 2020, the Alberta government had spent more than $1 million on that effort, including to earn a 4-1 victory in the Court of Appeal of Alberta.

Kenney said that a third of the Supreme Court judges dissented on Thursday further validated Alberta's position.

"Just because the court says that the federal government can punish people for filling up their gas tanks and driving to work and heating their homes, doesn't mean that the federal government should do that," he commented.

However, Bratt says the premier may have boxed himself in with an election commitment to hold a referendum before reintroducing a provincial carbon pricing program.

"Or does he just hope no one pays attention to that? Or do you have a referendum," Bratt asked, laughing, "where the provincial government is asking you to vote in favour of a provincial carbon tax? That would be fun…

"What happens if, as Scott Moe seemed to indicate today, Saskatchewan brings in its own provincial carbon tax, Alberta doesn't?"

The Saskatchewan premier said his province would be looking to "forge our own path without being subject to the punitive and ineffective" federal pricing, and Ontario's environment minister called the decision disappointing but one the province would respect.

With files from The Canadian Press and CTVNews.ca