A group of economists and lawyers is arguing that the current calculation of the societal cost of greenhouse gas emissions is the best estimate available, despite President Trump's decision to withdraw the metric and disband the interagency working group that developed it. The social cost of carbon, which currently sets the price of CO2 at $50 per ton emitted, has been used in cost-benefit analyses of more than 150 proposed and final rules. Among the experts signing the letter is Michael Greenstone, economics professor and director of the Energy Policy Institute at the University of Chicago, and a co-director of the Lab. Greenstone also co-led the original development of the working group under President Obama.