Published n Science on August 18, 2017 (Vol. 357, Issue 6352, pp. 655):
In March, President Trump's Executive Order 13783 disbanded the Interagency Working Group on the Social Cost of Greenhouse Gases (IWG) (1). IWG developed estimates for federal agencies to use in cost-benefit analyses of climate policies. IWG's most recent central estimate was $50 in global damages per ton of carbon dioxide, based on year 2020 emissions, converted from 2007 to 2017 dollars (2). Trump's Executive Order withdrew IWG's official valuations and instead instructed agencies to monetize climate effects using “the best available science and economics” (1). Yet IWG's estimates already are the product of the most widely peer-reviewed models and best available data (3). ...
The social cost of greenhouse gases should be regularly updated, especially to reflect the latest evidence about damage functions (10). Meanwhile, government and private sector analysts should continue using IWG's central estimate of $50 per ton of carbon dioxide with confidence that it is still the best estimate of the social cost of greenhouse gases.
Here is a summary of the best available science and economics: Greenstone et al., REEP (2013).