Billionaire climate change activist Tom Steyer said Wednesday night's debate showed Republican candidates are not serious about climate change, and therefore not ready for the White House.

"The Republican candidates haven't presented a plan to address climate change — and so those candidates still aren't ready to be president," Steyer said after the CNBC debate.

Steyer's group, NextGen Climate, has been pushing for Democratic and GOP candidates to endorse a 50 percent renewable energy goal, conducting ad campaigns in the cities where the presidential debates have taken place.

"The next president simply cannot stand by as climate change hurts our economy, kills jobs and increases costs for American families," Steyer said.

Read more on WashingtonExaminer.com