Former Vice President Al Gore compared the movement to stop global warming with abolishing slavery, the civil rights movement and gay rights in a speech at the EcoCity World Summit in Melbourne, Australia Thursday.

Gore's speech was addressing why the audience should treat global warming like apartheid, Climate Depot reports. Gore said that the "climate movement" is as much of an uphill battle as other great social movements.

"The climate movement, not least in cities, is right now in the tradition of all the great moral causes that have improved the circumstances of humanity throughout our history," he said. "The abolition of slavery. Women’s suffrage and women’s rights. The civil rights movement and the anti-apartheid movement in South Africa."

"The late Nelson Mandela said it was always impossible until it was done. The movement to stop the toxic phase of the nuclear arms race and more recently the gay rights movement," he added, before saying what the movements have in common.

"They all have met with ferocious resistance and have generated occasional feelings of despair from those who knew the right direction and wondered whether we could ever get there," Gore said.

Gore also had some positive reflections on the role of fossil fuels in human history. He admitted that those energy sources have had massive benefits for living conditions worldwide.

"We have had tremendous benefits from our reliance on fossil fuels. Poverty has declined, living standards have increased and we still depend on them for more than 80% of world’s energy," Gore said at the beginning of his talk. "Must we change?"

Gore went onto say that, yes, humanity must move away from those fuels, citing intensifying hurricanes and extreme weather. The politician turned documentary filmmaker did not address why hurricane activity has gone down over the last century, nor did he answer studies suggesting that extreme weather is not worsening.

Still, Gore said that "mother nature was screaming" at them that global warming is happening. He said younger people will ask their parents why they didn't act.

"If [future generations] live in a world of political disruption and chaos and diseases, stronger storms and more destructive floods…they would be justified in looking back at us and asking, ‘What were you thinking? Couldn’t you hear what the science was saying? What Mother Nature was screaming at you?'" Gore said.

Gore supported increasing renewable energy sources like wind turbines, saying that green jobs were growing. Such jobs are heavily subsidized, and the green energy sector has yet to achieve efficiency comparable to fossil fuels.