Guilbeault resigns, exposing Liberal climate fault line

Former environment minister Steven Guilbeault announced May 27 that he will resign as a member of Parliament this summer, following significant changes to federal climate policy under Prime Minister Carney. In his letter, the Montreal MP wrote that it is time for him to pursue his fight for environmental protection and against climate change in a different way. He will remain in the governing caucus until he resigns his seat later this summer. CP24 + 2

The timing is pointed. The announcement came less than two weeks after Carney and Alberta Premier Danielle Smith signed an energy pact pledging federal support for a new west-coast pipeline and slowing the pace of industrial carbon pricing. Guilbeault had already left cabinet in November 2025, after the initial announcement of the Alberta energy deal, which included a memorandum of understanding to work toward approval of a new bitumen pipeline; the final version was signed in Calgary on May 17. As an MP outside cabinet, he vocally urged the government not to compromise on industrial carbon pricing, but in May both governments released an implementation agreement that delayed the ramp-up of the price on big emitters. On his way out, Guilbeault said Canada is “backsliding” on climate action. CP24 + 4

Why it matters: This is the most visible internal sign of strain over Carney’s pivot from the Trudeau-era climate framework. Guilbeault — described by environmental observers as “the most ambitious environment minister Canada has ever had” — is not the only unhappy member; he has said other caucus members share his frustration with the Liberals’ environmental policy shift since the last election. His departure crystallizes the trade-off at the heart of Carney’s agenda: an energy-and-investment strategy built around pipelines and softened carbon pricing, set against the climate commitments that defined the party’s previous decade. It also opens a by-election in the Montreal riding of Laurier–Sainte-Marie, which he has held since 2019. The NarwhalCTVNews