Career environmentalist and longtime Liberal MP Steven Guilbeault resigned from cabinet Thursday, marking a dramatic rupture within Prime Minister Mark Carney’s government over its new energy accord with Alberta and what he described as a retreat from Canada’s climate commitments.
Guilbeault — once the public face of the Liberals’ climate agenda under Justin Trudeau and later shifted to the Heritage portfolio — said he could no longer reconcile the government’s direction with the environmental principles that have defined his life’s work. In a three-page letter, he warned that much of the policy he helped craft was being dismantled and delivered a pointed critique of the new memorandum of understanding with Alberta.
The accord outlines a plan to develop a new oil pipeline from Alberta to B.C.’s north coast and pledges that if it proceeds, Ottawa will lift the long-standing oil tanker ban to enable bitumen exports to Asia. It also grants Alberta an exemption from federal clean-electricity rules while strengthening industrial carbon pricing to support the Pathways carbon-capture megaproject. Guilbeault called the approach a “serious mistake,” saying B.C. and affected First Nations had not been consulted and that lifting the tanker ban would carry profound environmental risks.
Despite leaving cabinet, Guilbeault will continue to sit as the Liberal MP for Laurier–Sainte-Marie in Montreal. “My commitment to leaving a better world for the future of our children and our planet remains unchanged,” he wrote.
The resignation sent ripples through political and environmental circles. Rick Smith, president of the Canadian Climate Institute, praised Guilbeault’s decades of advocacy, calling him a “tireless and sincere” leader whose work has improved life for Canadians. Former cabinet colleague Marc Miller noted the personal difficulty of the decision, saying he admired Guilbeault’s integrity.
Inside the Liberal caucus, Guilbeault’s departure exposed simmering concerns. Some MPs had privately questioned the Alberta deal and whether the government’s climate credibility would hold. Guilbeault himself briefly walked out of a cabinet briefing earlier in the week as ministers were briefed on the plan.
Prime Minister Carney, in a statement, credited Guilbeault with shaping a more “hopeful horizon” for future generations and insisted that while they differed on how to advance climate goals, the government remains committed to climate ambition and competitiveness.
Reaction from Alberta was sharply divided. The provincial government welcomed the accord, and one UCP MLA mocked Guilbeault in the legislature as an “eco-cultist,” applauding his departure. Others, including Conservative MP Dan Albas, offered more measured respect, calling Guilbeault’s resignation on principle “an honourable act.”
The move now sets the stage for a cabinet shuffle, with Carney returning to Ottawa on Friday as speculation grows over who will take on the portfolio and how the government will navigate the political fallout of losing its most prominent environmental voice.
