Former Vice President Al Gore criticized Harvard University, his alma mater, on Wednesday for its failure to divest from the fossil fuel industry.

"Why would Harvard University continue to support with its finances an industry like this, that is in the process of threatening the future of humanity?" hesaid to graduating seniors during the university's Class Day ceremony. Gore framed climate change as “a moral issue,” comparable to the university’s investments in apartheid South Africa in the 1980s.

"The university did respond," he said of the university's divestment on that issue, "as they responded when they realized it was immoral to invest in tobacco stocks."

Harvard divested from South African companies and those doing business with the country, as well as from tobacco companies. The university also divested from companies working in Darfur.

Gore, who graduated from Harvard in 1969, said fossil fuel companies have adopted the same strategy as the tobacco industry, "designed to spread doubt and confusion."

On Earth Day last month, Harvard students, staff and alumni relaunched a campaign to get the university to divest from fossil fuel companies. The university refused to drop fossil fuel companies from its endowment investments after a similar call in 2013, but student organizers said they're confident things will be different this time.

Harvard's response to the call, however, has been consistent. In an emailed statement Wednesday, a university spokesman said Harvard's climate action plan recognizes the world must end its use of fossil fuels, but "while we agree on the urgency of this global challenge, we respectfully disagree with divestment activists on the means by which a university should confront it. Universities like Harvard have a crucial role to play in tackling climate change and Harvard is fully committed to leadership in this area through research, education, community engagement, dramatically reducing its own carbon footprint, and using our campus as a test bed for piloting and proving solutions." Harvard's endowment totaled around $39 billion as of September 2018, according to Harvard Magazine.

On Wednesday, Gore left the crowd with an invitation.

“I am also here to recruit you,” he told the Class of 2019. “We have work to do, all of us. We must see the seriousness and historic nature of this challenge.”

Gore said he refuses to believe we have the capacity to make changes of the magnitude.

"And if you doubt for one moment that we do have the ability to change or the will to change," he said, "please always remember that the will to change is itself a renewable resource."