Frustrated by McGill University's refusal to divest itself of investments in fossil fuels, Gregory Mikkelson felt it would be immoral to stay on.

"What it boiled down to, for me, was a matter of conscience," said Mikkelson, who taught at McGill for 18 years.

On Dec. 5, the university announced it would not sell off all stocks and investments in fossil fuel companies, despite calls from staff, students and the university's own senate to do so.

That makes it the third time the university has decided against fossil fuel divestment — it made the same decision in 2013 and again in 2016.

Mikkelson, who taught the philosophy of biology and environmental ethics, brought forward a motion last September requesting that McGill fully divest from fossil fuels.

"Because of the subject matter I research and teach, it became clear that this kind of action is imperative," Mikkelson told CBC.

That motion was approved in a majority vote, but all decisions made at senate must then go through the school's board of governors.

After the board's social responsibility committee, charged with determining whether divesting from fossil fuels would be a socially responsible decision, released its decision opposing divestment Dec. 5, Mikkelson felt he had no option.

He handed in his letter of resignation seven days later.

Divestment a financial risk: McGill

McGill University's board of governors has nixed proposals to divest from fossil-fuel companies three times since 2013, arguing divestment would put the university on a precarious financial footing and is not the best way to promote sustainability.

According to the committee's report, 8.7 per cent of McGill's current $1.7-billion investment pool is in the energy sector. The committee said that fully divesting from fossil fuels would pose a financial risk to the institution, and the university's other investment options would be too limited.

The committee also argued in its report that divestment is not the most effective way of making a positive impact on the environment.

The university has vowed to reduce greenhouse gas emissions by 58 per cent by 2025 and to achieve carbon neutrality by 2040.

But Mikkelson says the university's plans to reach those targets are too vague.

"While divestment would have been a clear and courageous move to make, this de-carbonization concept is complex and confusing," he said.

In a statement, the university said it cannot comment on matters involving its staff.

However, "the university is committed to reducing the overall carbon footprint of its investment portfolio, including those within the fossil fuel industry," it said in the statement.

But for Mikkelson, that simply isn't enough.

"Divestment works. It creates political pressure for governments to do the right thing," he said.

"One of the first examples of divestment is from South Africa which created political pressure that resulted in government action that then basically reduced the harms caused by the apartheid regime in South Africa."

Prof's resignation 'profound loss'

Annabelle Couture Guillet, a McGill student and member of Divest McGill, said Mikkelson's resignation is "a profound loss" for the school.

"Professor Mikkelson has been a driving force in this university on matters, not only of divestment but sustainability. He has created space for discussions of a high academic standard to happen," said Guillet.

Guillet said Divest McGill had been trying to get the school to divest from fossil fuels since 2012, and that Mikkelson had been supportive of the students from the beginning.

"The refusal to divest was really a failure to the students, but also to the faculty, the professors, the alumni and the donors," said Guillet.

"It's a failure to cut ties with an industry that profits from and actively fuels the climate industry."

Mikkelson said he plans to continue helping Divest McGill in an unofficial capacity.

Movement across Canada

Emma Pham, 20, on the fifth day of a hunger strike Friday. She is part of UBC’s chapter of the climate activist group Extinction Rebellion who pressured the school to promise to fully divest from fossil fuel companies in its $1.7-billion endowment fund. (Maggie MacPherson/CBC)

Last May, the Université du Québec à Montréal (UQAM) committed to fully divesting from fossil fuels in an unanimous decision.

In an interview with CBC News, Pierre Bélanger, executive director of UQAM's foundation, said the university has already fully divested from the industry. Previously, it had $3 million of investments in fossil fuels.

"There is a strong debate within the society about the fact that there is no future for a society with fossil fuels," Bélanger said.

"We had a debate here at the foundation to the fact that if there is an agreement that there is no future, why should we invest in something that we don't believe in?"

Listen to the full interview with Gregory Mikkelson here: McGill University's board of governors voted against a motion to divest the school's endowment from investments in fossil fuel companies. So Gregory Mikkelson, who taught environmental ethics and philosophy at McGill for 18 years, decided to divest himself of his job. 6:31

Bélanger said it was pressure from the school's students and staff that led them to that decision.

He said six months after the university fully divested, the university remains in good financial standing, despite that decision.

"It was possible to have the same kind of returns on our money when we invested in other fields, other than fossil fuels," said Bélanger.

Last November, Concordia University also committed to fully divesting from the fossil fuel industry by 2025.

In a release at the time, Concordia also said it has steadily decreased its investments in the coal oil and gas industry, with its current fossil fuel investments totalling $14 million of its $243 million in assets.

Emily Carson-Apstein, a member of Divest Concordia, said the school's decision came after years of student pressure.

She said that, while divestment does not necessarily hurt fossil fuel companies financially, it acts as a social statement.

"It's a public way of explaining to the world that we don't agree with the oil industry and what they do," Carson-Apstein said in an interview.

Earlier this month, the University of British Columbia also promised to fully divest its $1.7 billion endowment fund of fossil fuel investments, clarifying its position on the issue after students went on a 100-hour hunger strike.