Several prominent economists at the University of Chicago were original signatories of a joint letter from the Climate Leadership Council supporting a carbon tax, including Nobel Prize winners Eugene Fama and Lars Peter Hansen.

Forty-five economists had signed the Economists’ Statement on Carbon Dividends when the Wall Street Journal published it on January 16. Over 3,300 economists have now co-signed the document.

The Climate Leadership Council was founded in June 2017 with the goal of creating a carbon-tax system that “[returns] the income from a nation’s carbon fees directly to its citizens through carbon dividends,” according to their website.

The letter offers five policy recommendations, ranging from the implementation of a carbon tax to the creation of a dividend program for U.S. citizens. “A carbon tax offers the most cost-effective lever to reduce carbon emissions at the scale and speed that is necessary,” the letter says.

Other signatories include UChicago professor Austan Goolsbee and George Shultz, former dean of Booth.