EDMONTON -- Alberta Premier Rachel Notley, with her arch pipeline foe sitting just a few feet away in the front row, compared Trans Mountain protesters Saturday to dewy-eyed unicorn jockeys from Salt Spring Island, B.C.

"I would say to those who oppose our fight to build this pipeline, that they are being extremely foolish," Notley said in a speech to a teachers convention.

"Maybe on Salt Spring Island you can build an economy on condos and coffee shops, but not in Edmonton and not anywhere in Alberta.

"Here in Alberta, we ride horses -- not unicorns -- and I invite pipeline opponents to saddle up on something that is real."

Notley was rebutting a scheduled speech made earlier in the day to the Alberta Teachers' Association by environmental activist Tzeporah Berman, who listened intently to Notley's speech and applauded at the end.

Berman, who is also an academic and policy adviser, has come to symbolize the divisive debate in Alberta over how to balance environmental stewardship with its resource-dependent economy.

She is a former adviser to the province on oilsands policy under Notley, but has become a political lightning rod for her comments denouncing the Trans Mountain line expansion, which would take more oil from Alberta to the B.C. coast.

In her speech, Berman said striking a balance is already complex but has been made worse by public discourse suffused with hate and polarized ideologies on both sides.

She said the time is now to act on climate change as temperatures rise and the world faces the displacement of millions due to resultant droughts, floods, weather disasters and food shortages.

"No one is saying shut down the oil and gas industry overnight," said Berman.

"What we're saying is 'Right now it's big enough.'

"And we're at a moment in history where we need to look at cleaning it up and we're at a moment in history when we need to look at how to diversify our economy to make sure that we have resilient and safe jobs in the future."

Notley, meanwhile, said a realistic approach is needed for the environment, and that trying to stop the Trans Mountain expansion hurts families, workers and the economy, and will stifle progress to fight climate change in the long run.

The opposition United Conservatives and their leader, Jason Kenney, have said Notley's decision to bring Berman on board in 2016 to help guide oilsands policy despite her previous criticism of the industry reflects bad judgment.

Notley has denied that Berman, who left the advisory group in 2017, has become a political millstone around the neck of her NDP government, but has worked to distance her administration from Berman.

Berman said the vitriol has been difficult and that she has faced death threats.

"The attacks on my character have been meant to drown out what I'm saying, to foment fear and anger in Alberta that paralyzes us from progress. That's not leadership," said Berman.

"The hate is so thick that there can be no meaningful conversation about the future of energy policy."

Kenney, in a social media post, said the only thing Notley should be doing with Berman, whom he termed an "anti-energy zealot," is apologizing for hiring her in the first place.

"You gave Tzeporah Berman the credibility, the platform, the position, the profile of the government of Alberta. You never should have done it and it's time you just fessed up," said Kenney.

Kenney says his party will have an environmental platform ready for the 2019 spring election but will rescind Notley's carbon tax immediately if they become government.

Kenney has said he favours a charge on heavy emitters with funds going to technology to reduce greenhouse gas emissions.