WASHINGTON -- Former Vice President Al Gore sees parallels between the last two and a half weeks of budget chaos on Capitol Hill and the climate crisis: Many will deny there's a problem -- until they are ultimately compelled to take action by forces beyond their control.

"The tendency by many members of Congress to deny the reality of the government shutdown and the cost that would have accompanied a default on U.S. debt obviously mirrors the denial of the climate crisis and a refusal to recognize the cost of continuing to spew all this carbon into the atmosphere," Gore said Thursday.

But, he said, "when the markets began to send powerful signals that that was lunacy, they had an encounter with reality and they had to obviously back down."

Gore said this has made him optimistic that efforts to curb planet-warming greenhouse gas emissions can succeed. "We often see the resolution of seemingly impossible political challenges when a critical mass of support builds up to break through the obstacles holding it back, when large questions are resolved to a simple choice between what is right and what is wrong. Then change follows," Gore said.

Gore also compared climate change denial to other positions that once seemed entrenched and insurmountable, like the opposition to civil rights in the 1950s and '60s and, more recently, to gay marriage. "If someone had asked me five years ago how likely it is that gay marriage would become acceptable to the majority of Americans and laws would be changed, I probably would have said, 'I hope so, but I just don't think that's in the cards so quickly,'" said Gore. "But it was resolved into a choice between right and wrong, and the laws quickly changed."

In the case of climate change, he said, "Mother Nature is sending powerful signals that it's not acceptable to continue destroying the equilibrium of the climate in which human existence has thrived."

"More and more people are understanding that this too is a choice between what is right and what is wrong," he continued. "So I am optimistic."

Gore spoke to a small group of reporters on Thursday in advance of the third annual "24 Hours of Reality" event that his Climate Reality Project is hosting Oct. 22-23.

Gore also expressed support for the divestment movement that has been growing in popularity on college campuses in the U.S., referring to investment in fossil fuels as a "carbon bubble." The movement contends that investing in fossil fuels is a moral hazard but will become a financial hazard, too, when there is a global price on carbon emissions.

"This bubble is going to burst. No one can say with certainty when," said Gore. "But you can say with certainty that no more than one-third of these carbon assets can be burned, and hopefully not even that much."

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