Former Vice President Al Gore is urging voters who care about climate change to put aside their "misgivings" about both major party presidential nominees and vote for Hillary Clinton, and not a third-party candidate.

"First of all, I understand their feelings and misgivings," Gore said. "But if they are interested in my personal advice, I am voting for Hillary Clinton. I urge everyone else to do the same."

Gore made the comments in an interview with the progressive website Think Progress published Monday. The website asked him about his concerns that climate voters, by voting for the Green Party, could upset Clinton's chances in a general election. It noted that Gore himself was hurt by a third-party candidate when he lost to Republican George W. Bush in 2000.

Gore said voters concerned about climate change need only compare the policies of Clinton versus those of Donald Trump. Clinton has touted a solar energy initiative that would increase the resource by 700 percent by 2025, while backing President Obama's climate regulations called the Clean Power Plan.

Trump has said he would rescind the climate regulations and remove the U.S. from an international climate change accord agreed to in Paris last year.

"I particularly urge anyone who is concerned about the climate crisis, sees it as the kind of priority that I see it as, to look at the sharp contrast between the solar plan that Secretary Clinton has put forward, and her stated commitment to support the Clean Power Plan, and the contrast between what she has said and is proposing with the statements of the Republican nominee, which give me great concern," Gore said.

He discouraged anyone from voting for Green Party nominee Jill Stein, or any other third-party contender. Gore said the "harsh reality is that we have two principal choices" for president in November.

Gore's comments were followed by billionaire climate activist Tom Steyer, who released a report on Monday to help make the case for younger voters between the ages of 18-34 to vote for the candidate who makes the most sense for dealing with climate change. Steyer has endorsed Clinton.

"When we look at the consequences of this election, the choice between the candidates could not be more stark — and the voice of millennial voters has never been more important," Steyer said in a statement.

"Climate change is a top voting issue for millennials, and this generation has the ability to transition our economy to clean energy. Young voters have the power to shape this election and demand real solutions to our most urgent problems — but only if they vote."

Steyer and his group NextGen Climate endorsed Hillary Clinton in June. But many millennials have supported Sen. Bernie Sanders of Vermont before he conceded at the Democratic convention in July. Many voters are conflicted over whether to vote for Clinton after Sanders left the race, while many may choose not to vote at all.

Monday's report, compiled by the public policy group Demos, showed that without taking action on climate change, the earning potential of a 21-year-old college graduate in 2015 will drop by more than $126,000 in lifetime income and $187,000 in wealth.

"In total, without bold climate action, the millennial generation as a whole will lose nearly $8.8 trillion in lifetime income and their children will lose tens of trillions," Steyer and Demos said in a joint statement.

It concludes that the economic inequality this generation will experience compared to previous generations due to climate change can be averted by enacting policies that transition to 100 percent renewable energy by 2050.

The report is part of Steyer's $25 million campaign in battleground states to get millennials to register and vote in the general election.