; (2) the occurrence of extreme events, be it natural or man-made, which have significantly altered the shoreline or ecosystem since the last update; (3) the natural variability of shoreline and coastal environment; and (4) the volume of vessel traffic and general vulnerability to spilled pollutants. (d) Environmental sensitivity index product defined In this subsection, the term environmental sensitivity index product means a map or similar tool that is utilized to identify sensitive shoreline, coastal or offshore, resources prior to an oil spill event in order to set baseline priorities for protection and plan cleanup strategies, typically including information relating to shoreline type, biological resources, and human use resources. (e) Authorization of appropriations (1) In general There is authorized to be appropriated to the Under Secretary $7,500,000 to carry out subsection (a). (2) Availability Amounts appropriated or otherwise made available pursuant to paragraph (1) shall be available to the Under Secretary for the purposes set forth in such paragraph until expended.