; 5 U.S.C. App.) and section 3145 of title 40, United States Code. 203. Funding To carry out the program under section 201(b), the Secretary, in addition to amounts in the Fund, may use amounts that have been made available to the Secretary and are not otherwise obligated. III Revenue 301. Climate Change Obligations (a) In general Not later than 6 months after the date of the enactment of this Act, the Secretary of the Treasury or the Secretary's delegate (referred to in this title as the Secretary ) shall issue obligations under chapter 31 of title 31, United States Code (referred to in this title as climate change obligations ), the proceeds from which shall be deposited in the Fund. (b) Full faith and credit Payment of interest and principal with respect to any climate change obligation issued under this section shall be made from the general fund of the Treasury of the United States and shall be backed by the full faith and credit of the United States. (c) Exemption from local taxation All climate change obligations issued by the Secretary, and the interest on or credits with respect to such obligations, shall not be subject to taxation by any State, county, municipality, or local taxing authority. (d) Amount of Climate Change Obligations (1) In general Except as provided in paragraph (2), the aggregate face amount of the climate change obligations issued annually under this section shall be $200,000,000. (2) Additional obligations For any calendar year in which all of the obligations issued pursuant to paragraph (1) have been purchased, the Secretary may issue additional climate change obligations during such calendar year, provided that the aggregate face amount of such additional obligations does not exceed $800,000,000. (e) Funding The Secretary shall use funds made available to the Secretary and not otherwise obligated to carry out the purposes of this section. 302. Promotion (a) In general The Secretary shall promote the purchase of climate change obligations through such means as are determined