… Interagency Working Group (IWG) on Social Cost of Greenhouse Gases under Executive Order 12866. As the IWG explains “[the SCC] increases over time because future emissions are … Update of the Social Cost of Carbon for Regulatory Impact Analysis Under Executive Order 12866 (May 2013, Revised August 2016). … Interagency Working Group (IWG) on Social Cost of Greenhouse Gases under Executive Order 12866. As the IWG explains “[the SCC] increases over time because future emissions are …