Andrew Leach, a professor of energy economics at the University of Alberta, said some might read the project’s demise as a fatal blow to oil-sands development, but he interpreted Teck Resources’ decision as a pragmatic one.

“Teck was clear that it does not want a situation where one project has to answer for all of Canada’s climate policies and climate commitments,” he said. Moreover, he added, “global investors are not prepared to help a company the size of Teck to build a multibillion-dollar project. The global market was not prepared to be part of the political football.”

No new oil-sands mine has opened since 2018, but more than a dozen proposals are awaiting regulatory approval or investment decisions. Mr. Leach said some of those were economically and environmentally more viable than the Frontier project.

But resistance to new pipelines and high production costs have steadily reduced investments in oil-sands fields. There has been an exodus of international oil companies, including ConocoPhillips, Royal Dutch Shell and Equinor of Norway.

At the same time, there are questions about the market outlook. While world demand is roughly 100 million barrels a day, a figure that increases by 1 percent every year, the International Energy Agency projects that growth will begin to slow considerably in 2025. The agency says demand could fall to 67 million barrels a day in 2040, especially if governments increase regulation and electric cars become commonplace.

Reduced demand would focus production on places where it is cheapest, like Saudi Arabia.