Mankiw's title is quaint, given that we are now aware of "alternative facts." :
Readers of this blog will surely want to know about a new website: econofact.org, non-partisan publication designed to bring key facts and incisive analysis to the national debate on economic and social policies. It is written by leading academic economists from across the country who belong to the EconoFact Network, and published by the Edward R. Murrow Center for a Digital World at The Fletcher School at Tufts University."
There are a handful of issues posted there. None of these are focused on environmental economics but they are all very important to the workings of the U.S. economy.