Nov 3, 2021 12:39 PM EDT

Yellen calls climate fight ‘the greatest economic opportunity of our time’

U.S. Treasury Secretary Janet Yellen speaks to COP26 delegates following a keynote speech by British Chancellor of the Exc...

U.S. Treasury Secretary Janet Yellen speaks to COP26 delegates following a keynote speech by British Chancellor of the Exchequer, Rishi Sunak, on Nov. 03, 2021 in Glasgow, Scotland. Photo by Christopher Furlong/Getty Images

U.S. Treasury Secretary Janet Yellen on Wednesday described combatting climate change as both a huge financial challenge, with a price tag of $100 trillion, and “the greatest economic opportunity of our time.”

“Many renewables are now cheaper than carbon-based fuel alternatives and have lower long-term operating costs,” she said on a panel with Britain’s Treasury chief Rishi Sunak. “In many cases, it’s simply cost effective to go green.”