Mayor Pete Buttigieg wants the country to take climate change seriously, proposing a nationwide carbon tax to help reduce emissions.

“We’re going to have to have a carbon tax,” he told voters in Des Moines, Iowa on Tuesday.

He estimated that the federal government would have to spend as much as $10 billion to help develop solutions for climate change but said that the spending was worth it to prepare for a “multi-trillion dollar emergency.”

Buttigieg acknowledged that taxes were not popular but proposed to offer immediate rebates to consumers to ease the burden.

One idea he proposed was a taxpayer-funded “kit” to help make homes energy neutral.

“Imagine if a household in Iowa got a kit or a voucher from Uncle Sam, to help make you personally use, specifically your home, net zero emissions,” he said.

Buttigieg repeated his call for a carbon tax during a campaign stop at Stonyfield Organic Yogurt on Friday.

“We are going to need a carbon tax,” he said, admitting that “politicians are told not to mention the ‘t’ word” but suggested, “if we get it right, it will make most American families better off.”

He said that climate was the biggest security threat to the United States.

“Let’s call climate what it is, climate security, a life or death issue for our generation,” Buttigieg said.