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

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 and was a co-founder of Équiterre and the Quebec chief for Greenpeace.

He was first elected in 2019 during the government of Prime Minister Justin Trudeau. After serving first 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, as well as 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.

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,” he wrote in his statement.

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.”

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

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.

“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.

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.

In a social media statement, Carney said Guilbeault pursued “a more sustainable future” while in government. That included implementing the 2022 Kunming-Montréal Global Biodiversity Framework to conserve and protect 30 per cent of Canada’s lands and waters by 2030.

Rick Smith, president of the Canadian Climate Institute and a friend of the outgoing MP for 30 years, said Guilbeault worked with dedication and leaves a measurable legacy.

He 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.

“I’ve worked at the federal level for many years and I’m not sure that anyone has had the significant impact that he’s had in terms of improving the lives of Canadians in the future of our country.”

Asked whether he was discouraged to see such a prominent environmentalist leave Parliament Hill, Smith noted the federal government “has committed to many significant climate change policies.

“So I look forward to seeing those advance in the next little while,” he said.

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.

— with files from Lisa Johnson in Edmonton

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

Craig Lord, The Canadian Press

by The Canadian Press

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

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