Former cabinet minister Steven Guilbeault says he will resign as an MP this summer

Former environment minister Steven Guilbeault announced Wednesday that he will resign as a member of Parliament this summer following significant changes to federal climate policy under Prime Minister Mark Carney.

“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 on social media.

Read more:

• Steven Guilbeault quitting cabinet following pipeline deal
• A timeline of a cabinet resignation: Inside Guilbeault’s decision to resign
• Steven Guilbeault to announce resignation as member of Parliament on Wednesday

His announcement comes less than two weeks after 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 the decision comes after “careful consideration” weighing his past seven years as an MP. 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.

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

He was first elected in 2019 during the government of former prime minister Justin Trudeau. He spent time first as Heritage Minister and then nearly four years as environment minister, bringing in significant new policies to lower Canada’s greenhouse gas contributions, including a cap on emissions from the oil and gas sector, regulations to make Canada’s electricity grid emission-free by 2050, and a mandate to ramp up electric vehicle uptake so no more gas-powered passenger vehicles were sold after 2035.

In March 2025, after Carney replaced Trudeau, Guilbeault returned to the heritage portfolio as the Minister of Culture and official languages. He left cabinet in November 2025, after the initial announcement of Ottawa’s energy deal with Alberta, which included a memorandum of understanding to work toward the approval of a new bitumen pipeline.

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

While Guilbeault thanked his constituents in the Montreal riding of Laurier-Sainte-Marie, which he has represented since 2019, he signalled 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,” Guilbeault wrote in his statement.

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

Asked on his way into the Liberal caucus meeting whether the MOU 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.

“First and foremost what I want to do is thank … Steven Guilbeault for his many contributions,” Carney said.

The prime minister recalled working with Guilbeault when Carney was the United Nations’ special representative on climate action and finance. He said he expects he and Guilbeault will work together again in the future.

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

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.”

Many of Guilbeault’s Liberal colleagues had positive things to say about him on the way into the party’s caucus meeting on Wednesday.

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.

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

Conservative MP Michael Barrett said on his way into his party’s caucus meeting Wednesday that those who signed the letter should come out publicly with their criticisms.

“Mr. Guilbeault has the courage of his convictions and has seen that he doesn’t have that alignment with Mr. Carney,” he said.

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