Green Export Enhancement Act or the GREEN Act - Authorizes the President, subject to consultation and layover requirements of the Uruguay Round Agreements Act, to proclaim the modification or staged rate reduction of any duty in Schedule XX-United States of America, annexed to the Marrakesh Protocol to the General Agreement on Tariffs and Trade 1994, on environmental goods, as defined in a multilateral negotiation for the reciprocal elimination, reduction, or harmonization of duties under the auspices of the World Trade Organization, if the United States agrees to such modification or reduction in such a negotiation.