Marc Benioff, the co-CEO of Salesforce and owner of Time, on Thursday defended the magazine's selection of teenage climate activist Greta Thunberg as its Person of the Year.
"She has been the spokesperson that we have needed," Benioff said in a "Squawk Alley" interview from the World Economic Forum in Davos, Switzerland.
Benioff was partly responding to criticism this week from U.S. Treasury Secretary Steven Mnuchin, who questioned Thunberg's credentials to speak out on fossil fuel investment.
The 17-year-old Thunberg has become a leading voice on climate change over the last 18 months, beginning with her protest outside Swedish parliament in 2018 that gained widespread attention.
She has since helped bring thousands of young people to streets around the world as part of a Global Climate Strike and given high-profile speeches at the United Nations and the past two World Economic Forums.
"Look at what she has done over the last year," Benioff said in reference to Thunberg's 2019 speech in Davos. "It has been spectacular, and I think that a lot of the change and understanding that's happened around climate, a lot of it I think has been led by her."
Thunberg also attended this week's World Economic Forum, which had a focus on the intensifying climate crisis.
Thunberg was named Time's Person of the Year for 2019 last month, a decision that President Donald Trump said was "so ridiculous."
Trump has not only criticized Thunberg's climate activism but he previously called climate change a "hoax" pushed by the Chinese.
Trump has since said "nothing's a hoax" about it. But his administration has moved aggressively to roll back more than 80 environmental regulations, including a proposal to significantly change the nation's landmark environmental law, while also withdrawing the U.S. from the Paris Agreement.
Mnuchin continued the Trump administration's criticism of Thunberg on Thursday, deriding her calls to stop ongoing investments in fossil fuel exploration and extraction.
"Is she the chief economist or who is she? I'm confused," Mnuchin said in Davos, before adding this was "a joke. That was funny."
"After she goes and studies economics in college she can come back and explain that to us," Mnuchin said.
Thunberg responded in a series of tweets that didn't mention Mnuchin by name but included a graph that depicted rising carbon emissions.
"So either you tell us how to achieve this mitigation or explain to future generations and those already affected by the climate emergency why we should abandon our climate commitments," she wrote.
Thunberg's growing activism has coincided with a 12-month period that contained the hottest year on record for the world's oceans, the second-hottest year for global average temperatures and wildfires from the U.S. to the Amazon to Australia.
Thunberg told the global leaders at the World Economic Forum this week that their lack of action on climate change was "fueling the flames by the hour."
Benioff and his wife, Lynne Benioff, bought Time magazine in September 2018. Benioff is known to be outspoken on social and environmental issues.
He has urged companies to reorient their goals away from simply maximizing shareholder return, advocating for what he calls a "new capitalism."
On Thursday, he said more than 300 companies have agreed to his latest initiative to plant one trillion trees in the next 10 years.
Trump said the U.S., one of the world's leading carbon emitters, will join the initiative.
— CNBC's Sam Meredith contributed to this report.