Liberals prepare to lose climate champion as Guilbeault plans to quit Commons

OTTAWA — The resignation of one of the most prominent environmental voices in the Liberal caucus was held up Wednesday as a watershed moment for a government accused of prioritizing economic development over climate policy.

Former Liberal cabinet minister Steven Guilbeault has announced he will leave his seat as a member of Parliament this summer.

“I have come to the conclusion that it is time for me to pursue my fight for environmental protection and the fight against climate change in a different way,” the Montreal MP wrote in a letter posted to social media.

His announcement comes less than two weeks after Prime Minister Mark Carney and Alberta Premier Danielle Smith signed an energy pact that pledged federal support for a new pipeline to the West Coast and slowed the pace of industrial carbon pricing.

Guilbeault said his decision came after “careful consideration” of his past seven years as MP for Laurier-Sainte-Marie. He said he will remain in the Liberal caucus until he steps down.

The staunch environmentalist has become increasingly disillusioned in recent months by what he has called the dismantling of climate policies since Carney became prime minister in March 2025.

In a previous media statement, Guilbeault said he strongly opposed the agreement between Ottawa and Alberta and called the proposal to exempt Alberta from clean electricity regulations “a serious mistake.”

He wrote that “several elements of the climate action plan I worked on as minister of the environment have been, or are about to be, dismantled: the consumer carbon pricing, the zero-emission vehicle standard, the oil and gas sector emissions cap, the framework to eliminate fossil fuel subsidies and the clean electricity regulations.”

Asked on his way into the Liberal caucus meeting Wednesday whether the deal with Alberta was worth it, given Guilbeault’s decision to leave, Carney said, “Absolutely.”

Carney told reporters at the Cansec defence conference in Ottawa earlier Wednesday that he respects Guilbeault’s decision and thanked him for his service.

“We’ve worked closely together in a variety of areas and I’ve always enjoyed working with him,” Carney said.

Speaking in the House of Commons Wednesday, Guilbeault said he would be leaving the job with a sense of pride in what he has accomplished.

“There are many reasons that lead people to enter politics,” he said. “In my case, it was a desire to pursue my quest for a better environment, for the fight against climate change, for nature protection. These seven years, intense, demanding and deeply meaningful, have been among the most formative of my life.”

Guilbeault appeared to be fighting back tears as he thanked his family, friends, staff, volunteers and constituents.

“The struggle for our planet is defining for our generation, and I will continue to fight,” he said in French. “It was the honour of a lifetime to serve my community and my country.”

Green Party Leader Elizabeth May said she was “heartbroken” by Guilbeault’s decision to resign.

She questioned whether there is “room for anyone who cares about climate in the Liberal caucus,” citing the upcoming departure of former environment minister Jonathan Wilkinson and expected resignation of MP Nate-Erskine Smith.

The Liberals hold a thin majority government with 174 seats in the House of Commons.

The CBC reported last week that 14 Liberal MPs sent a letter to the prime minister at the end of April expressing their concerns about the government’s agreement with Alberta.

Guilbeault was a power player in Canada’s climate movement and was a co-founder of Équiterre and the Quebec chief for Greenpeace.

Greenpeace Canada executive director Christy Ferguson thanked Guilbeault for his decades of environmental work in a media statement Wednesday. She said his resignation signals a “deep loss of political ambition” on Canada’s climate goals.

“Steven’s departure underlines what we’ve been saying for months: Prime Minister Carney made election promises to protect nature and fight climate change, but over the last year he has rammed through an ‘extraction-first, nature and people last’ approach, prioritizing profit, further harming marginalized communities, and forcing political allies to make tough decisions,” Ferguson said.

Guilbeault was first elected in 2019 during the government of Prime Minister Justin Trudeau. After a stint as heritage minister he spent nearly four years as environment minister, during which he introduced and passed legislation enshrining Canada’s climate targets into law, along with multiple policies to regulate greenhouse gas emissions.

In March 2025, after Carney replaced Trudeau, Guilbeault returned to the heritage portfolio as the minister of culture and official languages. He was also Carney’s Quebec lieutenant.

He left cabinet in November 2025 after the initial announcement of Ottawa’s energy deal with Alberta, which included a memorandum of understanding on working toward the approval of a new bitumen pipeline.

The final version of that deal was signed by Carney and Smith in Calgary on May 17.

Guilbeault’s colleagues in the Liberal caucus had warm words for the departing MP on Wednesday. Many called him a friend and respected parliamentarian.

Conservative Leader Pierre Poilievre suggested Guilbeault should “cheer up” because many of the environmental policies from his tenure are still in place.

“Frankly, Mr. Guilbeault’s radical anti-development agenda, which Mr. Carney enthusiastically advocated in his own book, all of that remains in place,” he told reporters on Parliament Hill.

He claimed Liberal policies championed by Guilbeault have fuelled “justifiable resentment” among Albertans who are unable to get full work in the oil and gas sector.

Premier Smith has been a harsh critic of Guilbeault for years and claimed a win for Alberta when he resigned from cabinet last year.

On Tuesday, she was asked to respond to reports he was leaving the political arena.

“I wish him well in his future endeavours,” she said.

Transport Minister Steven MacKinnon was also a Trudeau-era minister. He suggested the political landscape has changed since then.

“It’s a different Liberal party … that is meeting the very urgent and critical demands of the moment. We’re in a trade war, there are wars in the Middle East, there’s a war in Europe. Indeed, we have a climate change challenge to meet and contribute to, and we’re going to continue doing all of that,” he said.

Rick Smith, president of the Canadian Climate Institute and a friend of the outgoing MP for 30 years, said Guilbeault deserves Canadians’ thanks for regulating toxic chemicals and plastics and expanding protected lands.

“These are all significant achievements that are going to stand the test of time. Not everyone can say that when they leave public service,” he said.

Guilbeault told reporters on his way out of the Liberal caucus meeting that he was “at peace” with his decision. He signalled in his social media statement that he believes he can accomplish more for the environment outside the House of Commons.

“Around the world, we have demonstrated what we can accomplish with ambition and determination. It is with this same conviction that I wish to continue this fight for the generations who will inherit our precious and unique blue planet,” he wrote in his statement.

— with files from Lisa Johnson in Edmonton

This report by The Canadian Press was first published May 27, 2026.

Craig Lord, The Canadian Press